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What You See Is What You Get

About monitor calibration

 

Look at the same image on 10 different computer monitors and you could very easily see 10 different versions of the image, where colour and contrast is concerned. For most people most of the time they are either not aware of the issue or it does not bother them. As long as it looks good (what ever that means).

It could be true to say that most if not all consumer PC monitors and laptop screens are set up to 'show off' the image, which usually means images are bright, contrasty and saturated. People also tend to adjust the image to suit taste - which usually is likewise the same.

From a perspective of giclee fine art printing this is of no use at all.

The subject of colour management is potentially quite difficult to grasp fully, but put simply we need a way to ensure we are seeing true colour on our screen and can be confident we will get the same true colour when we print an image. Strictly speaking there is whole other article that could be written about the notion of 'true colour'.

I am going to start with looking at computer monitor calibration.

First you need to understand how PC/laptop screens display colour, which is quite different to how a printer prints colour. A PC/laptop screen is effectively emitting light in three primary colour bands, of Red, Green and Blue (RGB colour space). How those colour lights are mixed gives the range of colours that the screen can 'effectively' display. The light is emitted from the screen, unlike a print where light is reflected off the paper. It therefore tends toward looking brighter and more luminous.

I am not going into colour wheel theory here - as an artist or photographer you are probably already familiar with that. But obviously black is produced by emitting the full level of Red, Green and Blue light, where White is a zero level of these three colours. A mid gray is 50% of all three colours (RGB) at the same time.

Every manufacturer of PC/laptop monitors has many technologies at their disposal to produce the final product - all of which will have their own particular impact of the image quality. Some technologies will be engineered towards a more accurate or more inclusive range of colours which can be displayed. The range of colour a screen can display is referred to as it's 'colour gamut'. All are slightly different, but no PC/laptop screen I am aware of is capable of actually showing the full range of possible colour.  The best ones obviously can show more of this colour gamut than the more budget/consumer products.

Serious artists/photographers/printers will opt to use a specialist PC monitor designed to show the biggest colour gamut in the most stable and accurate way possible. These monitors are not generally considered cheap, but I always believe in the saying - 'you get what you pay for'.  You can expect to pay upwards of £1,000 for a good monitor suitable for serious photographers/printers and digital artists. I will list a few as an appendix.

But even the very best monitor needs to be calibrated to show true colour on the screen. It can just do so more effectively. Calibration is a process to establish how accurate the screen is rendering colour (and greyscale) and then adjusting the output to more closely match the true reference.  For this purpose you need something called a 'spectrophotometer' and some specialist software that communicates with the screen.  These packages come in a wide range of prices from about £75 to over £6,000. That's a huge difference isn't it?

The difference is in the accuracy of the device and the sophistication in the software. Needless to say there is a package to suit every need.

The basics are the same however. A device (spectrophotometer) is placed on the screen to 'read' the colour it registers. The software renders to the screen a range of colours and grayscale values all of which have a known RGB value. The deviation from the expected value is computed and the monitor output is adjusted to make the output match the expected value as close as possible. That's it.

Once calibrated a special reference file is saved to the computer with the profile for this monitor - at this time. The computer uses this reference file (known as an ICC profile) to adjust the screen output display and if all was done properly what you see will be the closest that screen can get to displaying true accurate colour. This process needs to be performed on a regular basis, as the screen will tend to shift in colour display accuracy over time. Some professional studios my do this on a weekly schedule - even daily (but I doubt that is really necessary).

Bear in mind it is important to set your screen to it's optimum resolution and you need to let it warm up to best operating temperature (at least 30mins would be recommended).

Use of a reference image
It is helpful to have a reference image with which to judge how your screen is performing. I have one I use with a range of greyscale ramps, skin tones, skies and various other indicators. Some people without the benefit of a specrophotometer package will try and adjust the screen colour/brightness/contrast manually. That is certainly better than nothing and can help, but would not be as accurate.

I often get sent images to print (as digital files) that when received by the customer as a giclee print do not quite match their colour expectations. I know from the adherence to colour management guidelines I follow and the quality of my monitor/printer that I have produced accurate colour prints.  But that is not necessarily what customer was used to seeing on their screen - especially as virtually none will have a calibrated monitor. I can only urge you as an artist/photographer/designer to consider these points and look to equipping yourself with a good quality monitor and a calibration tool/package that best fits your budget.

If you can't trust what you see on your screen - you can't trust what a print will look like or how to adjust the image meaningfully, unless the image is never intended to be seen anywhere other than on your own screen.  And bear in mind too that even if you do calibrate your screen and share your images on the internet (web site) for example, you can rest assured that hardly anyone looking at your images will have a calibrated screen and you have no way of knowing just how that image looks to them.
Have a look at the greyscale ramp below. You should be able to see all the grey squares as evenly differentiated across the full range, and they should all look neutral (ie: no obvious colour hue in any of them).
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