Category Archives: Monitor Calibration

Monitors & Color Bit Depth

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Monitors and Color Bit Depth – yawn, yawn – Andy’s being boring again!

Well, perhaps I am, but I know ‘stuff’ you don’t – and I’m telling YOU that you need to know it if you want to get the best out of your photography – so there!

Let me begin by saying that NOTHING monitor-related has any effect on your captured images.  But  EVERYTHING monitor-related DOES have an effect on the way you SEE your images, and therefore definitely has an effect on your image adjustments and post-processing.

So anything monitor-related can have either a positive or negative effect on your final image output.

Bit Depth

I’m going to begin with a somewhat disconnected analogy, but bare with me here.

We live in the ‘real and natural world’, and everything that we see around us is ANALOGUE.  Nature exists on a natural curve and is full of infinite variation. In the digital world though, everything has to be put in a box.

We’ll begin with two dogs – a Labrador and a Poodle.  In this instance both natural  and digital worlds can cope with the situation, because nature just regards them for what they are, and digital can put the Labrador in a box named ‘Labrador’ and the Poodle in a separate box just for Poodles.

Let’s now imagine for a fleeting second that Mr. Lab and Miss Poodle ‘get jiggy’ with the result of dog number 3 – a Labradoodle.  Nature just copes with the new dog because it sits on natures ‘doggy curve’ half way between Mum and Dad.

But digital is having a bloody hissy-fit in the corner because it can’t work out what damn box to put the new dog in.  The only way we can placate digital is to give it another box, one for 50% Labrador and 50% Poodle.

Now if our Labradoodle grows up a bit then starts dating and makes out with another Labrador then we end up with a fourth dog that is 75% Labrador and 25% Poodle.  Again, nature just takes all in her stride, but digital in now having a stroke because it’s got no box for that gene mix.

Every time we give digital a new box we have effectively given it a greater bit depth.

Now imagine this process of cross-breed gene dilution continues until the glorious day arrives when a puppy is born that is 99% Labrador and only 1% Poodle.  It’ll be obvious to you that by this time digital has a flaming warehouse full of boxes that can cope with just about any gene mix, but alas, the last time bit depth was increased was to accommodate 98% Lab 2% Poodle.

Digital is by now quite old and grumpy and just can’t be arsed anymore, so instead of filling in triplicate forms to request a bit depth upgrade it just lumps our new dog in the same classification box as the previous one.

So our new dog is put in the wrong box.

Digital hasn’t been slap-dash though and put the pup in any old box, oh no.  Digital has put the pup in the nearest suitable box – the box with the closest match to reality.

Please note that the above mentioned boxes are strictly metaphorical, and no puppies were harmed during the making of this analogy.

Digital images are made up of pixels, and a pixel can be thought of as a data point.  That single data point contains information about luminance and colour.  The precision of that information is determined by the bit depth of the data

Very little in our ‘real world’ has a surface that looks flat and uniform.  Even a supposedly flat, uniform white wall on a building has subtle variations and graduations of colour and brightness/luminance caused by the angular direction of light and its own surface texture. That’s nature for you in the analogy above.

We are all familiar with RGB values for white being 255,255,255 and black being 0,0,0, but those are only 8 bit values.

8 bit allows for 256 discrete levels of information (or gene mix classification boxes for our Labradoodles), and a scale from 0 to 255 contains 256 values – think about it for a second!

At all bit depth values black is always 0,0,0 but white is another matter entirely:

8 bit = 256 discrete values so image white is 255,255,255

10 bit = 1,024 discrete values so image white is 1023,1023,1023

12 bit = 4,096 discrete values so image white is 4095,4095,4095

14 bit = 16,384 discrete values so image white is 16383,16383,16383

15 bit = 32,768 discrete values so image white is 32767,32767,32767

16 bit = 65,536 discrete values so image white should be 65535,65535,65535 – but it isn’t – more later!

And just for giggles here are some higher bit depth potentials:

24 bit = 16,777,216 discrete values

28 bit = 268,435,456 discrete values

32 bit = 4,294,967,296 discrete values

So you can see a pattern here.  If we double the bit depth we square the value of the information, and if we halve the bit depth the information we are left with is the square root of what we started with.

And if we convert to a lower or smaller bit depth “digital has fewer boxes to put the different dogs in to, so Labradoodles of varying genetic make-ups end up in the same boxes.  They are no longer sorted in such a precise manner”.

The same applies to our images. Where we had two adjacent pixels of slightly differing value in 16 bit, those same two adjacent pixels can very easily become totally identical if we do an 8 bit conversion and so we lose fidelity of colour variation and hence definition.

This is why we should archive our processed images as 16 bit TIFFS instead of 8 bit JPEGs!

In an 8 bit image we have black 0,0,0 and white 255,255,255 and ONLY 254 available shades or tones to graduate from one to the other.

Monitor Display Bit Depth

Whereas, in a 16 bit image black is 0,0,0 and white is 65535,65535,65535 with 65,534 intervening shades of grey to make the same black to white transition:

Monitor Display Bit Depth

But we have to remember that whatever the bit depth value is, it applies to all 3 colour channels:

Monitor Display Bit Depth Monitor Display Bit Depth Monitor Display Bit Depth

So a 16 bit image should contain a potential of 65536 values per colour channel.

How Many Colours?

So how many colours can our bit depth describe Andy?

Simple answer is to cube the bit depth value, so:

8 bit = 256x256x256 = 16,777,216 often quoted as 16.7 million colours.

10 bit = 1024x1024x1024 = 1,073,741,824 or 1.07 billion colours or EXACTLY 64x the value of 8 bit!

16 bit = 65536x65536x65536 = 281,474,976,710,656 colours. Or does it?

Confusion Reigns Supreme

Now here’s where folks get confused.

Photoshop does not WORK  in 16 bit, but in 15 bit + 1 level.  Don’t believe me? Go New Document, RGB, 16 bit and select white as the background colour.

Open up your info panel, stick your cursor anywhere in the image area and look at the 16 bit RGB read out and you will see a value of 32768 for all 3 colour channels – that’s 15 bit folks! Now double the 32768 value – yup, that’s right, you get 16 bit or 65,536!

Why does Photoshop do this?  Simple answer is ‘for speed’ – or so they say at Adobe!  There are numerous others reasons that you’ll find on various forums etc – signed and unsigned integers, mid-points, float-points etc – but really, do we care?

Things are what they are, and rumor has it that once you hit the save button on a 16 bit TIFF is does actually save out at 16 bit.

So how many potential colours in 16 bit Photoshop?  Dunno! But it’ll be somewhere between 35,184,372,088,832 and 281,474,976,710,656, and to be honest either value is plenty enough for me!

The second line of confusion usually comes from PC users under Windows, and the  Windows 24 bit High Color and 32 bit True Color that a lot of PC users mistakenly think mean something they SERIOUSLY DO NOT!

Windows 24 bit means 24 bit TOTAL – in short, 8 bits per channel, not 24!

Windows 32 bit True Color is something else again. Correctly known as 32 bit RGBA it contains 4 channels of 8 bits each; three 8 bit colour channels and an 8 bit Alpha channel used for transparency.

The same 32 bit RGBA colour (Mac call it ARGB) has been utilised on Mac OS for ever, but most Mac users never questioned it because it’s not quite so obvious in OSX as it is in Windows unless you look at the Graphics/Displays section of your System report, and who the Hell ever goes there apart from twats like me:

bit depth

Above you can see the pixel depth being reported as 32 bit colour ARGB8888 – that’s Apple-speak for Windows 32 bit True Colour RGBA.  But like a lot of ‘things Mac’ the numbers give you the real information.  The channels are ordered Alpha, Red, Green, Blue and the four ‘8’s give you the bit depth of each pixel, or as Apple put it ‘pixel depth’.

However, in the latter part of 2015 Apple gave OSX 10.11 El Capitan a 10 bit colour capability, though hardly anyone knew including ‘yours truly’.  I never have understood why they kept it ‘on the down-low’ but there was no fan-fare that’s for sure.

bit depth

Now you can see the pixel depth being reported as 30 bit ARGB2101010 – meaning that the transparency Alpha channel has been reduced from 8 bit to 2 bit and the freed-up 6 bits have been distributed evenly between the Red, Green and Blue colour channels.

Monitor Display

Your computer has a maximum display bit depth output capability that is defined by:

  • a. the operating system
  • b. the GPU fitted

Your system might well support 10 bit colour, but will only output 8 bit if the GPU is limited to 8 bit.

Likewise, you could be running a 10 bit GPU but if your OS only supports 8 bit, then 8 bit is all you will get out of the system (that’s if the OS will support the GPU in the first place).

Monitors have their own panel display bit depth, and panel bit depth costs money.

A lot of LCD panels on the market are only capable of displaying 8 bit, even if you run an OS and GPU that output 10 bit colour.

And then again certain monitors such as Eizo ColorEdge, NEC MultiSynch and the odd BenQ for example, are capable of displaying 10 bit colour from a 10 bit OS/GPU combo, but only if the monitor-to-system connection has 10 bit capability.  This basically means Display Port or HDMI connection.

As photographers we really should be looking to maximise our visual capabilities by viewing the maximum number of colour graduations captured by our cameras.  This means operating with the greatest available colour bit depth on a properly calibrated monitor.

Just to reiterate the fundamental difference between 8 bit and 10 bit monitor display pixel depth:

  • 8 bit = 256x256x256 = 16,777,216 often quoted as 16.7 million colours.
  • 10 bit = 1024x1024x1024 = 1,073,741,824 or 1.07 billion colours.

So 10 bit colour allows us to see exactly 64 times more colour on our display than 8 bit colour. (please note the word ‘see’).

It certainly does NOT add a whole new spectrum of colour to what we see; nor does it ‘add’ anything physical to our files.  It’s purely a ‘visual’ improvement that allows us to see MORE of what we ALREADY have.

I’ve made a pound or two from my images over the years and I’ve been happily using 8 bit colour right up until I bought my Eizo the other month, even though my system has been 10 bit capable since I upgraded the graphics card back in August last year.

The main reason for the upgrade with NOT 10 bit capability either, but for the 4Gb of ‘heavy lifting power’ for Photoshop.

But once I splashed the cash on a 10 bit display I of course made instant use of the systems 10 bit capability and all its benefits – of which there’s really only one!

The Benefits

The ability to see 64 times more colour means that I can see 64x more subtle variantions of the same colours I could see before.

With my wildlife images I find very little benefit if I’m honest, but with landscapes – especially sunset and twilight shots – it’s a different story.  Sunset and twighlight images have massive graduations of similar hues.  Quite often an 8 bit display will not be able to display every colour variant in a graduation and so will replace it with its nearest neighbor that it can display – (putting the 99% Lab pup in the 98% Lab box!).

This leads to a visual ‘banding’ on the display:

bit depth

The banding in the shot above is greatly exaggerated but you get the idea.

A 10 bit colour display also helps me to soft proof slightly faster for print too, and for the same reason.  I can now see much more subtle shifts in proofing when making the same tiny adjustments as I made when using 8 bit.  It doesn’t bring me to a different place, but it allows me to get there faster.

For me the switch to 10 bit colour hasn’t really improved my product, but it has increased my productivity.

If you can’t afford a 10 bit display then don’t stress as 8 bit ARGB has served me well for years!

But if you are still needing a new monitor display then PLEASE be careful what you are buying, as some displays are not even true 8 bit.

A good place to research your next monitor (if not taking the Eizo, NEC 10 bit route) is TFT Central

If you select the panel size you fancy and then look at the Colour Depth column you will see the bit depth values for the display.

You should also check the Tech column and only consider H-IPS panel tech.

Beware of 10 bit panels that are listed as 8 bit + FRC, and 8 bit panels listed as 6 bit + FRC.

FRC is the acronym for FRAME RATE CONTROL – also known as Temporal Dithering.  In very simple terms FRC involves making the pixels flash different colours at you at a frame rate faster than your eye can see.  Therefore you are fooled into seeing what is to all intents and purposes an out ‘n out lie.

It’s a tech that’s okay for gamers and watching movies, but certainly not for any form of colour management or photography workflow.

Do not entertain the idea of anything that isn’t an IPS, H-IPS or other IPS derivative.  IPS is the acronym for In Plane Switching technology.  This the the type of panel that doesn’t visually change if you move your head when looking at it!

So there we go, that’s been a bit of a ramble hasn’t it, but I hope now that you all understand bit depth and how it relates to a monitors display colour.  And let’s not forget that you are all up to speed on Labradoodles!

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Monitor Calibration Update

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Monitor Calibration Update

Okay, so I no longer NEED a new monitor, because I’ve got one – and my wallet is in Leighton Hospital Intensive Care Unit on the critical list..

What have you gone for Andy?  Well if you remember, in my last post I was undecided between 24″ and 27″, Eizo or BenQ.  But I was favoring the Eizo CS2420, on the grounds of cost, both in terms of monitor and calibration tool options.

But I got offered a sweet deal on a factory-fresh Eizo CS270 by John Willis at Calumet – so I got my desire for more screen real-estate fulfilled, while keeping the costs down by not having to buy a new calibrator.

monitor calibration update

But it still hurt to pay for it!

Monitor Calibration

There are a few things to consider when it comes to monitor calibration, and they are mainly due to the physical attributes of the monitor itself.

In my previous post I did mention one of them – the most important one – the back light type.

CCFL and WCCFL – cold cathode fluorescent lamps, or LED.

CCFL & WCCFL (wide CCFL) used to be the common type of back light, but they are now less common, being replaced by LED for added colour reproduction, improved signal response time and reduced power consumption.  Wide CCFL gave a noticeably greater colour reproduction range and slightly warmer colour temperature than CCFL – and my old monitor was fitted with WCCFL back lighting, hence I used to be able to do my monitor calibration to near 98% of AdobeRGB.

CCFL back lights have one major property – that of being ‘cool’ in colour, and LEDs commonly exhibit a slightly ‘warmer’ colour temperature.

But there’s LEDs – and there’s LEDs, and some are cooler than others, some are of fixed output and others are of a variable output.

The colour temperature of the backlighting gives the monitor a ‘native white point’.

The ‘brightness’ of the backlight is really the only true variable on a standard type of LCD display, and the inter-relationship between backlight brightness and colour temperature, and the size of the monitors CLUT (colour look-up table) can have a massive effect on the total number of colours that the monitor can display.

Industry-standard documentation by folk a lot cleverer than me has for years recommended the same calibration target settings as I have alluded to in previous blog posts:

White Point: D65 or 6500K

Brightness: 120 cdm² or candelas per square meter

Gamma: 2.2

monitor calibration update

The ubiquitous ColorMunki Photo ‘standard monitor calibration’ method setup screen.

This setup for ‘standard monitor calibration’ works extremely well, and has stood me in good stead for more years than I care to add up.

As I mentioned in my previous post, standard monitor calibration refers to a standard method of calibration, which can be thought of as ‘software calibration’, and I have done many print workshops where I have used this method to calibrate Eizo ColorEdge and NEC Spectraviews with great effect.

However, these more specialised colour management monitors have the added bonus of giving you a ‘hardware monitor calbration’ option.

To carry out a hardware monitor calibration on my new CS270 ColorEdge – or indeed any ColorEdge – we need to employ the Eizo ColorNavigator.

The start screen for ColorNavigator shows us some interesting items:

monitor calibration update

The recommended brightness value is 100 cdm² – not 120.

The recommended white point is D55 not D65.

Thank God the gamma value is the same!

Once the monitor calibration profile has been done we get a result screen of the physical profile:

monitor calibration update

Now before anyone gets their knickers in a knot over the brightness value discrepancy there’s a couple of things to bare in mind:

  1. This value is always slightly arbitrary and very much dependent on working/viewing conditions.  The working environment should be somewhere between 32 and 64 lux or cdm² ambient – think Bat Cave!  The ratio of ambient to monitor output should always remain at between 32:75/80 and 64:120/140 (ish) – in other words between 1:2 and 1:3 – see earlier post here.
  2. The difference between 100 and 120 cdm² is less than 1/4 stop in camera Ev terms – so not a lot.

What struck me as odd though was the white point setting of D55 or 5500K – that’s 1000K warmer than I’m used to. (yes- warmer – don’t let that temp slider in Lightroom cloud your thinking!).

monitor calibration updateAfter all, 1000k is a noticeable variation – unlike the brightness 20cdm² shift.

Here’s the funny thing though; if I ‘software calibrate’ the CS270 using the ColorMunki software with the spectro plugged into the Mac instead of the monitor, I visually get the same result using D65/120cdm² as I do ‘hardware calibrating’ at D55 and 100cdm².

The same that is, until I look at the colour spaces of the two generated ICC profiles:

monitor calibration update

The coloured section is the ‘software calibration’ colour space, and the wire frame the ‘hardware calibrated’ Eizo custom space – click the image to view larger in a separate window.

The hardware calibration profile is somewhat larger and has a slightly better black point performance – this will allow the viewer to SEE just that little bit more tonality in the deepest of shadows, and those perennially awkward colours that sit in the Blue, Cyan, Green region.

It’s therefore quite obvious that monitor calibration via the hardware/ColorNavigator method on Eizo monitors does buy you that extra bit of visual acuity, so if you own an Eizo ColorEdge then it is the way to go for sure.

Having said that, the differences are small-ish so it’s not really worth getting terrifically evangelical over it.

But if you have the monitor then you should have the calibrator, and if said calibrator is ‘on the list’ of those supported by ColorNavigator then it’s a bit of a JDI – just do it.

You can find the list of supported calibrators here.

Eizo and their ColorNavigator are basically making a very effective ‘mash up’ of the two ISO standards 3664 and 12646 which call for D65 and D50 white points respectively.

Why did I go CHEAP ?

Well, cheaper…..

Apart from the fact that I don’t like spending money – the stuff is so bloody hard to come by – I didn’t want the top end Eizo in either 27″ or 24″.

With the ‘top end’ ColorEdge monitors you are paying for some things that I at least, have little or no use for:

  • 3D CLUT – I’m a general sort of image maker who gets a bit ‘creative’ with my processing and printing.  If I was into graphics and accurate repro of Pantone and the like, or I specialised in archival work for the V & A say, then super-accurate colour reproduction would be critical.  The advantage of the 3D CLUT is that it allows a greater variety of SUBTLY different tones and hues to be SEEN and therefore it’s easier to VISUALLY check that they are maintained when shifting an image from one colour space to another – eg softproofing for print.  I’m a wildlife and landscape photographer – I don’t NEED that facility because I don’t work in a world that requires a stringent 100% colour accuracy.
  • Built-in Calibrator – I don’t need one ‘cos I’ve already got one!
  • Built-in Self-Correction Sensor – I don’t need one of those either!

So if your photography work is like mine, then it’s worth hunting out a ‘zero hours’ CS270 if you fancy the extra screen real-estate, and you want to spend less than if buying its replacement – the CS2730.  You won’t notice the extra 5 milliseconds slower response time, and the new CS2730 eats more power – but you do get a built-in carrying handle!

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Your Monitor – All You Ever Wanted to Know

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Your Monitor – All You Ever Wanted to Know, and the stuff you didn’t – but need to!

I need a new monitor, but am undecided which to buy.  I know exactly which one I’d go for if money was no object – the NEC Spectraview Reference 302, but money is a very big object in that I ain’t got any spare!

But spend it I’ll have to – your monitor is the window on to your images and so is just about THE most important tool in your photographic workflow.  I do wish people would realize/remember that!

Right now my decision is between 24″ and 27″, Eizo or BenQ.  The monitor that needs replacement due to backlight degradation is my trusty HP LP2475W – a wide gamut monitor that punched way above its original price weight, and if I could find a new one I’d buy it right now – it was THAT good.

Now I know more than most about the ‘numbers bit’ of photography, and this current dilemma made me think about how much potential for money-wasting this situation could be for those that don’t ‘understand the tech’ quite as much as I do.

So I thought I’d try and lay things out for you in a simple and straight forward blog post – so here goes.

The Imaging Display Chain

Image Capture:

Let’s take my landscape camera – the Nikon D800E.  It is a 36 megapixel DSLR set to record UNCOMPRESSED 14 bit Raw files.

The RAW image produced by this camera has a pixel dimension of 7360 x 4912 and a pixel area of 36,152,320 pixels.

The horizontal resolution of this beastly sensor is approximately 5200 pixels per inch, each pixel being 4.88 µm (microns) in diameter – that’s know as pixel pitch.

During the exposure, the ANALOGUE part of the senor sees the scene in full spectrum colour and tone through its Bayer Array – it gathers an analogue image.

When the shutter closes, the DIGITAL side of the imaging sensor then basically converts the analogue image into a digital render with a reproduction accuracy of 14 bits per pixel.

And let’s not forget the other big thing – colour space.  All dslr cameras capture their images in their very own unique sensor colour space.  This bares little to no resemblance to either of the three commonly used digital colour management workflow colour spaces of sRGB, AdobeRGB1998 or ProPhotoRGB.

But for the purposes of digital RAW workflow, RAW editors such as Lightroom do an exceptional job of conserving the majority if not all the colours captured by the camera sensor, by converting the capture colour space to that of ProPhotoRGB – basically because it’s by far the largest industry standard space with the greatest spread of HSL values.

So this RAW file that sits on my CF card, then gets ingested by my Mac Pro for later display on my monitor is:

  • 1.41 inches on its long edge
  • has a resolution of around 5,200 pixels per inch
  • has a reproduction accuracy for Hue, Saturation & Luminance of 14 bits
  • has a colour space unique to the camera, which can best be reproduced by the ProPhotoRGB working colour space.

Image Display:

Now comes the tricky bit!

In order to display an image on a monitor, said monitor has to be connected to your computer via your graphics card or GPU output. This creates a larger number of pitfalls and bear traps for the unsuspecting and naive!

Physical attributes of a monitor you need to bare in mind:

  1. Panel Display Colour Bit Depth
  2. Panel Technology – IPS etc
  3. Monitor Panel Backlight – CCFL, WCCFL, LED etc
  4. Monitor Colour Look-Up Table – Monitor On-Board LUT (if applicable)
  5. Monitor connectivity
  6. Reliance on dedicated calibration device or not

The other consideration is your graphics card Colour Look-Up Table – GPU LUT

1.Monitor Panel Display Colour Bit Depth – All display monitors have a panel display colour bit depth – 8 bit or 10 bit.

I had a client turn up here last year with his standard processing setup – an oldish Acer laptop and an Eizo Colour Edge monitor – he was very proud of this setup, and equally gutted at his stupidity when it was pointed out to him.

The Eizo was connected to the laptop via a DVI to VGA lead, so he had paid a lot of good money for a 10 bit display monitor which he was feeding via a connection that was barely 8 bit.

Sat next to the DVI input on the Eizo was a Display Port input – which is native 10 bit. A Display Port lead doesn’t cost very much at all and is therefore the ONLY sensible way to connect to a 10 bit display – provided of course that your machine HAS a Display Port output – which his Acer laptop did not!

So if you are looking at buying a new monitor make sure you buy one with a display bit depth that your computer is capable of supporting.

There is visually little difference between 10 bit and 8 bit displays until you view an image at 100% magnification or above – then you will usually see something of an increase in colour variation and tonal shading, provided that the image you are viewing has a bit depth of 10+.  The difference is often quoted at its theoretical value of 64x –  (1,073,741,824 divided by 16,777,216).

So, yes, your RAW files will LOOK and APPEAR slightly better on a 10 bit monitor – but WAIT!

There’s more….how does the monitor display panel achieve its 10 bit display depth?  Is it REAL or is it pseudo? Enter FRC or Frame rate Control.

The FRC spoof 10 bit display – frame rate control quite literally ‘flickers’ individual pixels between two different HSL values at a rate fast enough to be undetectable by the human eye – the viewers brain gets fooled into seeing an HSL value that isn’t really there!

monitor

Here’s why I hate FRC !

Personally I have zero time for FRC technology in panels – I’d much prefer a good solid 8 bit wide gamut panel without it than a pseudo 10 bit; which is pretty much the same 8 bit panel with FRC tech and a higher price tag…Caveat Emptor!

2. Panel Technology – for photography there is only really one tech to use, that of IPS or In Plane Switching.  The main reasons for this are viewing angle and full colour gamut.

The more common monitors, and cheaper ones most often use TN tech – Twisted Nematic, and from a view angle point of view these are bloody awful because the display colour and contrast vary hugely with even just an inch or two head movement.

Gamers don’t like IPS panels because the response time is slow in comparison to TN – so don’t buy a gaming monitor for your photo work!

There are also Vertical Alignment (VA) and Plane to line Switching (PLS) technologies out there, VA being perhaps marginally better than TN, and PLS being close to (and in certain cases better than) IPS.

But all major colour work monitor manufacturers use IPS derivative tech.

3. Monitor Panel Backlight – CCFL, WCCFL, LED

All types of TFT (thin film transistor) monitor require a back light in order to view what is on the display.

Personally I like – or liked before it started to get knackered – the wide cold cathode fluorescent (WCCFL) backlight on the HP LP2475W, but these seem to have fallen by the wayside somewhat in favour of LED backlights.

The WCCFL backlight enabled me to wring 99% of the Adobe1998 RGB colourspace out of a plain 8 bit panel on the old HP, and it was a very even light across the whole of the monitor surface.  The monitor itself is nearly 11 years old, but it wasn’t until just over 12 months ago that it started to fade at the corners.  Only since the start of this year (2017) has it really begun to show signs of more severe failure on the right hand 20% – hence I’ll be needing a new one soonish!

But modern LED backlights have a greater degree of uniformity – hence their general supersedence of WCCFL.

4. Colour Look-Up Tables or LUTs

Now this is a bit of an awkward one for some folk to get their heads around, but really it’s simple.

Most monitors that you can buy have an 8 bit LUT which is either fixed, or variable via a number of presets available within the monitor OSD menu.

When it comes to calibrating a ‘standard gamut with fixed LUT’ monitor, the calibration software makes its alterations to the LUT of the GPU – not that of the monitor.

With monitors and GPUs that are barely 8 bit to begin with, the act of calibration can lead to problems.

A typical example would be an older laptop screen.  A laptop screen is driven by the on-board graphics component or chipset within the laptop motherboard.  Older MacBooks were the epitome of this setups failure for photographers.

The on-board graphics in older MacBooks were barely 8 bit from the Apple factory, and when you calibrated them they fell to something like 6 bit, and so a lot of images that contained varied tones of a similar Hue displayed colour banding:

monitor

An example of image colour banding due to low GPU LUT bit depth.
The banding is NOT really there, it just illustrates the lack of available colours and tones for the monitor display.

This phenomenon used to be a pain in the bum when choosing images for a presentation, but was never anything to panic over because the banding is NOT in the image itself.

Now if I display this same RAW file in Lightroom on my newer calibrated 15″ Retina MacBook Pro I still see a tiny bit of banding, though it’s not nearly this bad.  However, if I connect an Eizo CS2420 using a DisplayPort to HDMI cable via the 10 bit HDMI port on the MBP then there is no banding at all.

And here’s where folk get confused – none of what we are talking about has a direct effect on your image – just on how it appears on the monitor.

When I record a particular shade of say green on my D800E the camera records that green in its own colour space with an accuracy of 14 bits per colour channel.  Lightroom will display it’s own interpretation of that colour green.  I will make adjustments to that green in HSL terms and then ask Lightroom to export the result as say a TIFF file with 16 bits of colour accuracy per channel – and all the time this is going on I’m viewing the process on a monitor which has a display colour bit depth of 8 bit or 10 bit and that is deriving its colour from a LUT which could be 8 bit, 14 bit or 16 bit depending on what make and model monitor I’m using!

Some people get into a state of major confusion when it comes to bits and bit depth, and to be honest there’s no need for it.  All we are talking about here is ‘fidelity of reproduction’ on the monitor of colours which are FIXED and UNALTERABLE in your RAW file, and of the visual impact of your processing adjustments.

The colours contained in our image are just numbers – nothing more than that.

Lightroom will display an image by sending colour numbers through the GPU LUT to the monitor.  I can guarantee you that even with the best monitor in the world in conjunction with the most accurate calibration hardware money can buy, SOME of those colour numbers will NOT display correctly!  They will be replaced in a ‘relative colourmetric manner’ by their nearest neighbor in the MONITOR LUT – the colours the monitor CAN display.

Expensive monitors with 14 bit or 16 bit LUTs mean less colours will be ‘replaced’ than when using a monitor that has an 8 bit LUT, and even more colours will be replaced if we scale back our ‘spend’ even further and purchase a standard gamut sRGB monitor.

Another advantage of the pricier 14/16 bit wide gamut dedicated photography monitors from the likes of Eizo, NEC and BenQ is the ability to do ‘hardware calibration’.

Whereas the ‘standard’ monitor calibration mentioned earlier makes it’s calibration changes primarily to the GPU LUT, and therefore somewhat ‘stiffles’ its output bit depth; with hardware calibration we can internally calibrate the monitor itself and leave the GPU running as intended.

That’s a slight over-simplification, but it makes the point!

5. Monitor Connectivity. By this I mean connection type:

monitor

VGA or D-Sub 15. Awful method of connection – went out with the Ark. If you are using this then “stop it”!

monitor

DVI – nothing wrong with this connection format whatsoever, but bare in mind it’s an 8 bit connection.

monitor

Dual Link DVI – still only 8 bit.

monitor

Displayport – 10 bit monitor input connection.

monitor

HDMI left, Displayport right – both 10 bit connections.

6. Reliance on dedicated calibration device or not – this is something that has me at the thin end of a sharp wedge if I consider the BenQ option.

I own a perfectly serviceable ColorMunki Photo, and as far as I can see, hardware calibration on the Eizo is feasible with this device. However, hardware calibration on BenQ system software does not appear to support the use of my ColorMunki Photo – so I need to purchase an i1 Display, which is not a corner I really want to be backed into!

Now remember how we defined my D800E Raw file earlier on:

  • has a pixel dimension of 7360 x 4912 and a pixel area (or resolution) of 36,152,320 pixels.
  • 1.41 inches on its long edge
  • has a resolution of around 5,200 pixels per inch
  • has a reproduction accuracy for Hue, Saturation & Luminance of 14 bits
  • has a colour space unique to the camera, which can best be reproduced by the ProPhotoRGB working colour space.

So let’s now take a look at the resolution spec for, say, the NEC Spectraview Reference 302 monitor.  It’s a 30″ panel with an optimum resolution of 2560 x 1600 pixels – that’s 4Mp!

The ubiquitous Eizo ColorEdge CG2420 has a standard 24 inch resolution of 1920 x 1200 pixels – that’s 2.3Mp!

The BenQ SW2700PT Pro 27in IPS has 2560 x 1440, or 3.68Mp resolution.

Yes, monitor resolution is WAY BELOW that of the image – and that’s a GOOD THING.

I HATE viewing unedited images/processing on my 13″ Retina MBP screen – not just because of any possible calibration issue, or indeed that of its diminutive size – but because of its whopping 2560 x 1600, 4Mp resolution crammed into such a small space.

The individual pixels are so damn tiny the lull you into a false sense of security about one thing above all else – critical image sharpness.

Images that ‘appear tack sharp’ on a high resolution monitor MIGHT prove a slight disappointment when viewed on another monitor with a more conventional resolution!

So there we have it, and I hope you’ve learned something you didn’t know about monitors.

And remember, understanding what you already have, and what you want to buy is a lot more advantageous to you than the advice of some bloke in a shop who’s on a sales commission!

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Monitor Brightness.

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Monitor Brightness & Room Lighting Levels.

I had promised myself I was going to do a video review of my latest purchase – the Lee SW150Mk2 system and Big and Little Stopper filters I’ve just spent a Kings ransom on for my Nikon 14-24mm and D800E:

Lee SW150 mk2,Lee Big Stopper,Lee Little Stopper,Lee Filters, Nikon 14-24, Nikon, Nikon D800E, landscape photography,Andy Astbury,Wildlife in Pixels

PURE SEX – and I’ve bloody well paid for this! My new Lee SW150 MkII filter system for the Nikon 14-24. Just look at those flashy red anodised parts – bound to make me a better photographer!

But I think that’ll have to wait while I address a question that keeps cropping up lately.  What’s the question?

Well, that’s the tricky bit because it comes in many guises. But they all boil down to “what monitor brightness or luminance level should I calibrate to?”

Monitor brightness is as critical as monitor colour when it comes to calibration.  If you look at previous articles on this blog you’ll see that I always quote the same calibration values, those being:

White Point: D65 – that figure takes care of colour.

Gamma: 2.2 – that value covers monitor contrast.

Luminance: 120 cdm2 (candelas per square meter) – that takes care of brightness.

Simple in’it….?!

However, when you’ve been around all this photography nonsense as long as I have you can overlook the possibility that people might not see things as being quite so blindingly obvious as you do.

And one of those ‘omissions on my part’ has been to do with monitor brightness settings COMBINED with working lighting levels in ‘the digital darkroom’.  So I suppose I’d better correct that failing on my part now.

What does a Monitor Profile Do for your image processing?

A correctly calibrated monitor and its .icc profile do a really simple but very mission-critical job.

If we open a new document in Photoshop and fill it with flat 255 white we need to see that it’s white.  If we hold an ND filter in front of our eye then the image won’t look white, it’ll look grey.

If we hold a blue filter in front of our eye the image will not look white – it’ll look blue.

That white image doesn’t exist ‘inside the monitor’ – it’s on our computer!  It only gets displayed on the monitor because of the graphics output device in our machine.

So, if you like, we’re on the outside looking in; and we are looking through a window on to our white image.  The colour and brightness level in our white image are correct on the inside of the system – our computer – but the viewing window or monitor might be too bright or too dark, and/or might be exhibiting a colour tint or cast.

Unless our monitor is a totally ‘clean window’ in terms of colour neutrality, then our image colour will not be displayed correctly.

And if the monitor is not running at the correct brightness then the colours and tones in our images will appear to be either too dark or too bright.  Please note the word ‘appear’…

Let’s get a bit fancy and make a greyscale in Photoshop:

monitor brightness,monitor calibration,monitor luminance,ColorMunki,i1 Display,spectrophotometer,colourimeter,ambient light,work space,photography,digital darkroom,Andy Astbury,Wildlife in Pixels,gamma,colour correction,image processing

The dots represent Lab 50 to Lab 95 – the most valuable tonal range between midtone and highlight detail.

Look at the distance between Lab 50 & Lab 95 on the three greyscales above – the biggest ‘span’ is the correctly calibrated monitor.  In both the ‘too bright & contrasty’ and the ‘too dark low contrast’ calibration, that valuable tonal range is compressed.

In reality the colours and tones in, say an unprocessed RAW file on one of our hard drives, are what they are.  But if our monitor isn’t calibrated correctly, what we ‘see’ on our monitor IS NOT REALITY.

Reality is what we need – the colours and tones in our images need to be faithfully reproduced on our monitor.

And so basically a monitor profile ensures that we see our images correctly in terms of colour and brightness; it ensures that we look at our images through a clean window that displays 100% of the luminance being sent to it – not 95% and not 120% – and that all our primary colours are being displayed with 100% fidelity.

In a nutshell, on an uncalibrated monitor, an image might look like crap, when in reality it isn’t.  The shit really starts to fly when you start making adjustments in an uncalibrated workspace – what you see becomes even further removed from reality.

“My prints come out too dark Andy – why?”

Because your monitor is too bright – CALIBRATE it!

“My pics look great on my screen, but everyone on Nature Photographers Network keeps telling me they’ve got too much contrast and they need a levels adjustment.  One guy even reprocessed one – everyone thought his version was better, but frankly it looked like crap to me – why is this happening Andy?

“Because your monitor brightness is too low but your gamma is too high – CALIBRATE it!  If you want your images to look like mine then you’ve got to do ALL the things I do, not just some of ’em – do you think I do all this shit for fun??????????……………grrrrrrr….

But there’s a potential problem;  just because your monitor is calibrated to perfection, that does NOT mean that everything will be golden from this point on

Monitor Viewing Conditions

So we’re outside taking a picture on a bright sunny day, but we can’t see the image on the back of the camera because there’s too much daylight, and we have to dive under a coat with our camera to see what’s going on.

But if we review that same image on the camera in the dark then it looks epic.

Now you have all experienced that…….

The monitor on the back of your camera has a set brightness level – if we view the screen in a high level of ambient light the image looks pale, washed out and in a general state of ultra low contrast.  Turn the ambient light down and the image on the camera screen becomes more vivid and the contrast increases.

But the image hasn’t changed, and neither has the camera monitor.

What HAS changed is your PERCEPTION of the colour and luminance values contained within the image itself.

Now come on kids – join the dots will you!

It does not matter how well your monitor is calibrated, if your monitor viewing conditions are not within specification.

Just like with your camera monitor, if there is too much ambient light in your working environment then your precisely calibrated monitor brightness and gamma will fail to give you a correct visualization or ‘perception’ of your image.

And the problems don’t end there either; coloured walls and ceilings reflect that colour onto the surface of your monitor, as does that stupid luminous green shirt you’re wearing – yes, I can see you!  And if you are processing on an iMac then THAT problem just got 10 times worse because of the glossy screen!

Nope – bead-blasting your 27 inches of Apple goodness is not the answer!

Right, now comes the serious stuff, so READ, INGEST and ACT.

ISO Standard 3664:2009 is the puppy we need to work to (sort of) – you can actually go and purchase this publication HERE should you feel inclined to dump 138 CHF on 34 pages of light bedtime reading.

There are actually two ISO standards that are relevant to us as image makers; ISO 12646:2015(draft) being the other.

12646 pertains to digital image processing where screens are to be compared to prints side by side (that does not necessarily refer to ‘desktop printer prints from your Epson 3000’).

3664:2009 applies to digital image processing where screen output is INDEPENDENT of print output.

We work to this standard (for the most part) because we want to process for the web as well as for print.

If we employ a print work flow involving modern soft-proofing and otherwise keep within the bounds of 3664 then we’re pretty much on the dance-floor.

ISO 3664 sets out one or two interesting and highly critical working parameters:

Ambient Light White Point: D50 – that means that the colour temperature of the light in your editing/working environment should be 5000Kelvin (not your monitor) – and in particular this means the light FALLING ON TO YOUR MONITOR from within your room. So room décor has to be colour neutral as well as the light source.

Ambient Light Value in your Editing Area: 32 to 64 Lux or lower.  Now this is what shocks so many of you guys – lower than 32 lux is basically processing in the dark!

Ambient Light Glare Permissible: 0 – this means NO REFLECTIONS on your monitor and NO light from windows or other light sources falling directly on the monitor.

Monitor White Point – D65 (under 3664) and D50 (under 12646) – we go with D65.

Monitor Luminance – 75 to 100 cdm2 (under 3664) and 80 to 120 cdm2 (under 12646 – here we begin to deviate from 3664.

We appear to be dealing with mixed reference units, but 1 Lux = 1 cdm2 or 1 candela per square metre.

The way Monitor Brightness or Luminance relates to ambient light levels is perhaps a little counter-intuitive for some folk.  Basically the LOWER your editing area Lux value the LOWER your Monitor Brightness or luminance needs to be.

Now comes the point in the story where common sense gets mixed with experience, and the outcome can be proved by looking at displayed images and prints; aesthetics as opposed numbers.

Like all serious photographers I process my own images on a wide-gamut monitor, and I print on a wide-gamut printer.

Wide gamut monitors display pretty much 90% to100% of the AdobeRGB1998 colour space.

What we might refer to as Standard Gamut monitors display something a little larger than the sRGB colour space, which as we know is considerably smaller than AdobeRGB1998.

monitor brightness,monitor calibration,monitor luminance,ColorMunki,i1 Display,spectrophotometer,colourimeter,ambient light,work space,photography,digital darkroom,Andy Astbury,Wildlife in Pixels,gamma,colour correction,image processing

Left is a standard gamut/sRGB monitor and right is a typical wide gamut/AdobeRGB1998 monitor – if you can call any NEC ‘typical’!

Find all the gory details about monitors on this great resource site – TFT Central.

At workshops I process on a 27 inch non-Retina iMac – this is to all intents and purposes a ‘standard gamut’ monitor.

I calibrate my monitors with a ColorMunki Photo – which is a spectrophotometer.  Spectro’s have a tendency to be slow, and slightly problematic in the very darkest tones and exhibit something of a low contrast reaction to ‘blacks’ below around Lab 6.3 (RGB 20,20,20).

If you own a ColorMunki Display or i1Dispaly you do NOT own a spectro, you own a colorimeter!  A very different beast in the way it works, but from a colour point of view they give the same results as a spectro of the same standard – plus, for the most part, they work faster.

However, from a monitor brightness standpoint, they differ from spectros in their slightly better response to those ultra-dark tones.

So from a spectrophotometer standpoint I prefer to calibrate to ISO 12646 standard of 120cdm2 and control my room lighting to around 35-40 Lux.

Just so that you understand just how ‘nit-picking’ these standards are, the difference between 80cdm2 and 120 cdm2 is just 1/2 or 1/3rd of a stop Ev in camera exposure terms, depending on which way you look at it!

However, to put this monitor brightness standard into context, my 27 inch iMac came from Apple running at 290 cdm2 – and cranked up fully it’ll thump out 340 cdm2.

Most stand-alone monitors you buy, especially those that fall under the ‘standard gamut’ banner, will all be running at massively high monitor brightness levels and will require some severe turning down in the calibration process.

You will find that most monitor tests and reviews are done with calibration to the same figures that I have quoted – D65, 120cdm2 and Gamma 2.2 – in fact this non-standard set up has become so damn common it is now ‘standard’ – despite what the ISO chaps may think.

Using these values, printing out of Lightroom for example, becomes a breeze when using printer profiles created to the ICC v2 standard as long as you ‘soft proof’ the image in a fit and proper manner – that means CAREFULLY, take your time.  The one slight shortcoming of the set up is that side by side print/monitor comparisons may look ever so slightly out of kilter because of the D65 monitor white point – 6,500K transmitted white point as opposed to a 5,000K reflective white point.  But a shielded print-viewer should bring all that back into balance if such a thing floats your boat.

But the BIG THING you need to take away from the rather long article is the LOW LUX VALUE of you editing/working area ambient illumination.

Both the ColorMunki Photo and i1Pro2 spectrophotometers will measure your ambient light, as will the ColorMunki Display and i1 Display colorimeters, to name but a few.

But if you measure your ambient light and find the device gives you a reading of more than 50-60 lux then DO NOT ask the device to profile for your ambient light; in fact I would not recommend doing this AT ALL, here’s why.

I have a main office light that is colour corrected to 5000K and it chucks out 127 Lux at the monitor.  If I select the ‘measure and calibrate to ambient’ option on the ColorMunki Photo it eventually tells me I need a monitor brightness or luminance of 80 cdm2 – the only problem is that it gives me the same figure if I drop the ambient lux value to 100.

Now that smells a tad fishy to me……..

So my advice to anyone is to remove the variables, calibrate to 120 cdm2 and work in a very subdued ambient condition of 35 to 40 Lux. I find it easier to control my low lux working ambient light levels than bugger about with over-complex calibration.

To put a final perspective on this figure there is an interesting page on the Apollo Energytech website which quotes lux levels that comply with the law for different work environments – don’t go to B&Q or Walmart to do a spot of processing, and we’re all going to end up doing hard time at Her Madges Pleasure –  law breakers that we are!

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Colormunki Photo Update

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Colormunki Photo Update

Both my MacPro and non-retina iMac used to be on Mountain Lion, or OSX 10.8, and nope, I never updated to Mavericks as I’d heard so many horror stories, and I basically couldn’t be bothered – hey, if it ain’t broke don’t fix it!

But, I wanted to install CapOne Pro on the iMac for the live-view capabilities – studio product shot lighting training being the biggest draw on that score.

So I downloaded the 60 day free trial, and whadyaknow, I can’t install it on anything lower than OSX 10.9!

Bummer thinks I – and I upgrade the iMac to OSX 10.10 – YOSEMITE.

Now I was quite impressed with the upgrade and I had no problems in the aftermath of the Yosemite installation; so after a week or so muggins here decided to do the very same upgrade to his late 2009 Mac Pro.

OHHHHHHH DEARY ME – what a pigs ear of a move that turned out to be!

Needless to say, I ended up making a Yosemite boot installer and setting up on a fresh HDD.  After re-installing all the necessary software like Lightroom and Photoshop, iShowU HD Pro and all the other crap I use, the final task arrived of sorting colour management out and profiling the monitors.

So off we trundle to X-Rite and download the Colormunki Photo software – v1.2.1.  I then proceeded to profile the 2 monitors I have attached to the Mac Pro.

Once the colour measurement stage got underway I started to think that it was all looking a little different and perhaps a bit more comprehensive than it did before.  Anyway, once the magic had been done and the profile saved I realised that I had no way of checking the new profile against the old one – t’was on the old hard drive!

So I go to the iMac and bring up the Colormunki software version number – 1.1.1 – so I tell the software to check for updates – “non available” came the reply.

Colormunki software downloads

Colormunki software downloads

Colormunki v1.2.1 for Yosemite

Colormunki v1.2.1 for Yosemite

So I download 1.2.1, remove the 1.1.1 software and restart the iMac as per X-Rites instructions, and then install said 1.2.1 software.

Once installation was finished I profiled the iMac and found something quite remarkable!

Check out the screen grab below:

iMac screen profile comparrisons.

iMac screen profile comparisons. You need to click this to open full size in a new tab.

On the left is a profile comparison done in the ColourThink 2-D grapher, and on the right one done in the iMacs own ColourSynch Utility.

In the left image the RED gamut projection is the new Colormunki v1.2.1 profile. This also corresponds to the white mesh grid in the Colour Synch image.

Now the smaller WHITE gamut projection was produced with an i1Pro 2 using the maximum number of calibration colours; this corresponds to the coloured projection in the Coloursynch window image.

The GREEN gamut projection is the supplied iMac system monitor profile – which is slightly “pants” due to its obvious smaller size.

What’s astonished me is that the Colormunki Photo with the new software v1.2.1 has produced a larger gamut for the display than the i1 Pro 2 did under Mountain Lion OSX 10.8

I’ve only done a couple of test prints via softproofing in Lightroom, but so far the new monitor profile has led to a small improvement in screen-to-print matching of the some subtle yellow-green and green-blue mixes, aswell as those yellowish browns which I often found tricky to match when printing from the iMac.

So, my advice is this, if you own a Colormunki Photo and have upgraded your iMac to Yosemite CHECK your X-Rite software version number. Checking for updates doesn’t always work, and the new 1.2.1 Mac version is well worth the trouble to install.

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Monitor Calibration with ColorMunki

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Monitor Calibration with ColorMunki Photo

Following on from my previous posts on the subject of monitor calibration I thought I’d post a fully detailed set of instructions, just to make sure we’re all “singing from the same hymn sheet” so to speak.

Basic Setup

_D4R7794

Put the ColorMunki spectrophotometer into the cover/holder and attach the USB cable.

_D4R7798

Always keep the sliding dust cover closed when storing the ColorMunki in its holder – this prevents dust ingress which will effect the device performance.

BUT REMEMBER – slide the cover out of the way before you begin the calibration process!

colormunkiSpecCover

Install the ColorMunki software on your machine, register it via the internet, then check for any available updates.

Once the software is fully installed and working you are ready to begin.

Plug the USB cable into an empty USB port on your computer – NOT an external hub port as this can sometimes cause device/system communication problems.

Launch the ColorMunki software.

The VERY FIRST THING YOU NEED TO DO is open the ColorMunki software preferences and ensure that it looks like the following screen:

PC: File > Preferences

Mac: ColorMunki Photo > Preferences

Screen Shot 2013-10-17 at 11.28.32

The value for the Tone Response Curve MUST be set to 2.2 which is the default value.

The ICC Profile Version number MUST be set to v2 for best results – this is NOT the default.

Ensure the two check boxes are “ticked”.**

** These settings can be something of a contentious issue. DDC & LUT check boxes should only be “ticked” if your Monitor/Graphics card combination offers support for these modes.

If you find these settings make your monitor become excessively dark once profiling has been completed, start again ensuring BOTH check boxes are “unticked”.

Untick both boxes if you are working on an iMac or laptop as for the most part these devices support neither function.

For more information on this, a good starting point is a page on the X-Rite website available on the link below:

http://xritephoto.com/ph_product_overview.aspx?ID=1115&Action=Support&SupportID=5561

If you are going to use the ColorMunki to make printer profiles then ensure the ICC Profile Version is set to v2.

By default the ColorMunki writes profiles in ICC v4 – not all computer operating systems can function correctly from a graphics colour aspect; but they can all function perfectly using ICC v2.

You should only need to do this operation once, but any updates from X-Rite, or a re-installation of the software will require you to revisit the preferences panel just to check all is well.

Once this panel is set as above Click OK and you are ready to begin.

 

Monitor Calibration

This is the main ColorMunki GUI, or graphic user interface:

Screen Shot 2013-10-17 at 12.32.58

Click Profile My Display

Screen Shot 2013-10-17 at 11.17.49

Select the display you want to profile.

I use what is called a “double desktop” and have two monitors running side by side; if you have just a single monitor connected then that will be the only display you see listed.

Click Next>.

Screen Shot 2013-10-17 at 11.18.18

Select the type of display – we are talking here about monitor calibration of a screen attached to a PC or Mac so select LCD.

Laptops – it never hurts a laptop to be calibrated for luminance and colour, but in most cases the graphics output LUT (colour Look Up Table) is barely 8 bit to begin with; the calibration process will usually reduce that to less than 8 bit. This will normally result in the laptop screen colour range being reduced in size and you may well see “virtual” colour banding in your images.

Remedy: DON’T PROCESS ON A LAPTOP – otherwise “me and the boys” will be paying you a visit!

Select Advanced.

Deselect the ambient light measurement option – it can be expensive to set yourself up with proper lighting in order to have an ICC standard viewing/processing environment; daylight (D65) bulbs are fairly cheap and do go a long way towards helping, but the correct amount of light and the colour of the walls and ceiling, and the exclusion of extraneous light sources of incorrect colour temperature (eg windows) can prove somewhat more problematic and costly.

Processing in darkened room without light is by far the easiest, cheapest and most cost-effective way of obtaining correct working conditions.

Set the Luminance target Value to 120 (that’s 120 candelas per square meter if you’re interested!).

Set the Target White Point to D65 (that’s 6500 degrees Kelvin – mean average daylight).

Click Next>.

Screen Shot 2013-10-17 at 11.19.44

With the ColorMunki connected to your system this is the screen you will be greeted with.

You need to calibrate the device itself, so follow the illustration and rotate the ColorMunki dial to the indicated position.

Once the device has calibrated itself to its internal calibration tile you will see the displayed GUI change to:

Screen Shot 2013-10-17 at 11.20.26

Follow the illustration and return the ColorMunki dial to its measuring position.

Screen Shot 2013-10-17 at 11.20.49

Click Next>.

Screen Shot 2013-10-17 at 11.21.11

With the ColorMunki in its holder and with the spectrophotometer cover OPEN for measurement, place the ColorMunki on the monitor as indicated on screen and in the image below:

XR-CLRMNK-01

We are now ready to begin the monitor calibration.

Click Next>.

The first thing the ColorMunki does is measure the luminosity of the screen. If you get a manual adjustment prompt such as this (indicates non-support/disabling of DDC preferences option):

ColorMunki-Photo-display-screen-111

Simply turn adjust the monitor brightness slowly until the indicator line is level with the central datum line; you should see a “tick” suddenly appear when the luminance value of 120 is reached by your adjustments.

LCDs are notoriously slow to respond to changes in “backlight brightness” so make an adjustment and give the monitor a few seconds to settle down.

You may have to access your monitor controls via the screen OSD menu, or on Mac via the System Preferences > Display menu.

Once the Brightness/Luminance of the monitor is set correctly then ColorMunki will proceed will proceed with its monitor output colour measurements.

In order for you to understand monitor calibration and what is going on here is a sequence of slides from one of my workshops on colour management:

moncal1

moncal2

moncal3

moncal4

Once the measurements are complete the GUI will return to the screen in this form.

Screen Shot 2013-10-17 at 11.26.29

Either use the default profile name, or one of your own choice and click Save.

NOTE: Under NO CIRCUMSTANCES can you rename the profile after it has been saved, or any other .icc profile for that matter, otherwise the profile will not work.

Click Next>.

Screen Shot 2013-10-17 at 11.27.00

Click Save again to commit the new monitor profile to you operating system as the default monitor profile.

You can set the profile reminder interval from the drop down menu.

Click Next>.

Screen Shot 2013-10-17 at 12.32.58

Monitor calibration is now complete and you are now back to the ColorMunki startup GUI.

Quit or Exit the ColorMunki application – you are done!

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Screen Capture logos denoting ColorMunki & X-Rite are the copyright of X-Rite.

Monitor Calibration Devices

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Colour management is the simple process of maintaining colour accuracy and consistency between the ACTUAL COLOURS in your image, in terms of Hue, Saturation and Luminosity; and those reproduced on your RGB devices; in this case, displayed on your monitor. Each and every pixel in your image has its very own individual RGB colour values and it is vital to us as photographers that we “SEE” these values accurately displayed on our monitors.

If we were to visit The National Gallery and gaze upon Turners “Fighting Temeraire” we would see all those sumptuous colours on the canvass just as J.M.W. intended; but could we see the same colours if we had a pair of Ray Bans on?

No, we couldn’t; because the sunglasses behave as colour filters and so they would add a “tint” to every colour of light that passes through them.

What you need to understand about your monitor is that it behaves like a filter between your eyes and the recorded colours in your image; and unless that “filter” is 100% neutral in colour, then it will indeed “tint” your displayed image.

So, the first effect of monitor calibration is that the process NEUTRALIZES any colour tint in the monitor display and so shows us the “real colours” in our images; the correct values of Hue and Saturation.

Now imagine we have an old fashioned Kodak Ektachrome colour slide sitting in a projector. If we have the correct wattage bulb in the projector we will see the correct LUMINOSITY of the slide when it is projected.

But if the bulb wattage is too high then the slide will project too brightly, and if the bulb wattage is too low then the projected image will not be bright enough.

All our monitors behave just like a projector, and as such they all have a brightness adjustment which we can directly correlate to our old fashioned slide projector bulb, and this brightness, or backlight control is another aspect of monitor calibration.

Have you done a print that comes out DARKER than the image displayed on the screen?

If you have then your monitor backlight is too bright!

And so, the second effect of monitor calibration is the setting of the correct level of brightness or back lighting of our monitor in order for us to see the true Luminosity of the pixels in our images.

Without accurate Monitor Calibration your ability to control the accuracy of colour and overall brightness of your images is severely limited.

I get asked all the time “what’s the best monitor calibration device to use” so, above is a short video (no sound) I’ve made showing the 3D and 2D plots of profiles I’ve just made for the same monitor using teo different monitor calibration devices/spectrophotometers from opposite ends of the pricing scale.

The first plot you see in black is the AdobeRGB1998 working colour space – this is only shown as a standard by which you can judge the other two profiles; if you like, monitor working colour spaces.

The yellow plot that shows up as an overlay is a profile done with an Xrite ColourMunki Photo, which usually retails for around £300 – and it clearly shows this particular monitor rendering a greater number of colours in certain areas than are contained in the Adobe1998 reference space.

The cyan plot is the same monitor, but profiled with the i1Photo Pro 2 spectro – not much change out of £1300 thank you very much – and the resulting profile virtually an identical twin of the one obtained with the ColorMunki which retails for a quarter of the price!

Don’t get me wrong, the i1 is a far more efficient monitor calibration device if you want to produce custom PRINTER profiles as well, but if you are happy using OEM profiles and just want perfect monitor calibration then I’d say the ColorMunki Photo is the more sensible purchase; or better still the ColorMunki Display at only around £110.

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Monitor, Is Yours Up To The Job?

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Is Your Monitor Actually Up To The Job?

As photographers we have to take something of a “leap of faith” that the monitor we use to view and process our images on is actually up to the job – or do we?

No – is the short answer!  As a Photoshop & Lightroom educator I try and teach this mystical thing called “Colour Management” – note the correct spelling of the word COLOUR!

The majority of amateur photographers (and a few so-called pros come to that!) seem to think that colour management is some great complicated edifice; or even some sort of “re-invention of the wheel” – and so they either bury their head in the sand or generally “pooh-pooh” the idea as unnecessary.

Well, it’s certainly NOT complicated, but it certainly IS necessary.

The first stage in a colour managed workflow is to ensure that your monitor is calibrated – in other words it is working at the correct brightness level, and the correct colour balance or white point – this will ensure that when your computer sends pure red to your monitor, pure red is seen on the screen; not red with a blue tint to it!

But correct calibration of your monitor is fairly useless if your monitor cannot reproduce a large variation of colour – in other words, if its’ colour gamut is too small.

And it’s Monitor Colour Gamut that I want to look at in this post.

The first thing I’d like you to do is open up Photoshop and go to the Colour Settings – that’s Edit>Colour Settings, or shift+cmd+K on Mac, or shift+Ctrl+K on PC.

Once this dialogue box is open, set it up as follows:

Screen Shot 2013-11-18 at 13.47.30

This is the optimum setup of Photoshop for digital photography as ProPhoto is the best colour space for preserving the largest number of colours captured by your dslr sensor; far better than AdobeRGB1998 – but that’s another story.

If you like you can click the SAVE button and then give this settings profile a name – I call mine ProPhoto_Balanced_CC

Now that you are working with the largest colour palette possible inside Photoshop I want you to go to File>New and created a new 500×500 pixel square with a resolution of 300 pixels per inch with the settings as follows:

Screen Shot 2013-11-18 at 13.58.34

Click OK and you should now have a white square.

Now go to your foreground colour, click it to bring the colour palette dialogue box into view and manually add the following values indicated by the small red arrows:

Screen Shot 2013-11-18 at 14.06.52

The colour will look a little different than it does in the jpeg above.

So now we have a rather lurid sickly-looking green square in the ProPhoto colour space.

Now duplicate the image TWICE and then go to Window>Arrange>3up Vertical and you should end up with a display looking like this:

unconverted

Now comes the point of the exercise – click on the tab for the centre image and go Edit>Convert to Profile and choose AdobeRGB(1998) as the destination space (colour space).

Then click on the tab for the left hand image and go Edit>Convert to Profile and choose sRGB as the destination space.

Here’s the thing – if your display DOES NOT look like this:

MonitorColourDisplay

and all three squares look the same as the square on the left then your monitor only has a small sRGB colour gamut and is going to severely inhibit your ability to process your images properly or with any degree of colour accuracy.

Monitors rely on their Colour Look-up Table or LUT in order to display colour. Calibration of the monitor can reduce the size of the available range of colours in the LUT if it’s not big enough in the first place, and so calibration can indeed make things worse from a colour point of view; BUT, it will still ensure the monitor is set to the correct levels of brightness and colour neutrality; so calibration is still a good idea.

Laptops are usually the best illustration of this small LUT problem; normally their display gamuts are barely 8bit sRGB to begin with, and if calibration drops the LUT to below 8bit then the commonest problem you see is colour banding in your images.

If however, your display looks like the image above then you’re laughing!

Why is a large monitor colour gamut essential for digital photography?  Well it’s all to do with those colour spaces:

Screen Shot 2013-11-18 at 14.56.11

If you look at the image above you’ll see the three standard primary working colour spaces of ProPhoto, AdobeRGB(1998) and sRGB overlaid for comparison with each other.  There’s also a 4th plot – this is the input space of the Canon 1Dx dslr – in other words, it encompasses all the colours the sensor of that camera can record.

In actual fact, some colours can be recorded by the camera that lie OUTSIDE even the ProPhoto colour space!

But you can clearly see that the Adobe space looses more camera-captured colour than ProPhoto – hence RAW file handlers like Lightroom work in Prophoto (or to be more strictly true MelissaRGB – but that’s yet another story!) in order to at least preserve as many of the colours captured by the camera as possible.

Even more camera colour is lost to the sRGB colour space.

So this is why we should always have Photoshop set to a default ProPhoto working space – the archival images we produce will therefore retain as much of the original colours captured by the camera as possible.

If we now turn our attention back to monitors – the windows on to our images – we can now deduce that:

a. If a monitor can only display sRGB at best, then we will only be able to see a small portion of the cameras captured colour.

b. However, if the monitor has a larger colour gamut and a bigger LUT both in terms of colour spectrum and bit depth, then we will see a lot more of the original capture colours – and the more we can see then more effectively we can colour manage.

Monitors are available that can display the Adobe colour gamut, indeed quite a few can display more colours – but if you are on a tight budget these can seem more than expensive to say the least.

A good monitor that I recommend quite a lot – indeed I use one myself – is the HP LP2475W, well worth the price if you can find one; and with a bit of tweaking it will display 98%+ of the AdobeRGB colour space in all three primary colours and even some of the warmer colours that are only ProPhoto:

Screen Shot 2013-11-18 at 15.40.07

The green plot is the Adobe space, the red plot is the HP LP2475W display colour space.

So it’s a good buy if you can find one.

However, there’s a catch – there always is! This monitor relies on the LUT of the graphics card driving it – plugged into the modest 512Mb nVidea GT120 on my Mac Pro it is brilliant and competes at every level with the likes of Eizo ColourEdge and NEC Spectraviews for all practical purposes.  But plugged into the back of a laptop then it can only reproduce what the lower specification graphics chips can supply it with.

So there we have it, a simple way to test if your monitor is giving you the best advantage when it comes to processing your images – food for thought?

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