A Colour Conundrum


These days, it seems that nearly all electronic devices – digital cameras, phones, webcams, fridges and kettles have the ability to capture fantastic, colourful images in up to 16.7 million glorious colours – the wide gamut colour-space that is RGB. 256 levels of Red, 256 levels of Green and 256 of Blue. Actually, not kettles - yet!

Fridges? Yes, it’s true. The camera takes a picture of the contents of your fridge each time the door is closed. This picture is displayed on the fridge's front panel. Photo: ©Samsung.


The traditional printing industry can only dream of huge gamut colour-spaces because CMYK (Cyan, Magenta, Yellow, Black - the process colour model used by printers since the 1906) has a vastly reduced gamut, only allowing approximately one million available colours. Incidentally, one only requires Cyan, Magenta and Yellow to create most of the colours available to a traditional litho printer. And when printing images in CMYK, black is often used sparingly to add depth to colours. Black is a Key colour to which the other colours are registered - hence the letter K in CMYK rather than B.

RGB images look amazingly vibrant on today’s Retina and OLED displays and in an ideal world we would keep all of our images in RGB to retain the massive colour-space resulting in a huge visual benefit when producing digital brochures published for internet use. All that luscious RGB colour, visible to all. However, when preparing the images for litho printing we are required to convert RGB to CMYK thus throwing away all that colour goodness. Simply, the colours often become dull, less vibrant or subdued. Altering the conversion profile can help however, it isn’t an exact science.

A colour spectrum created in RGB with one half converted to CMYK using Photoshop.


Ultimately, the finest way to recover from the unadulterated rape of converting images to CMYK is to print a set of calibrated paper proofs and painstakingly treat each CMYK image to a Photoshop makeover. The end result obviously cannot mimic the colours of RGB but, with a little skill, an acceptable tonal recovery is possible.

Some publishers have an RGB colour workflow which keeps all the images in full glorious RGB until the very end of the production process when outputting the files for the printer. Any colour correction or image editing is done in RGB. They then pass the images through an automated profile which converts everything, on the fly, from RGB to CMYK and everyone is happy. Or, so they are led to believe...

Photographers might not be quite so happy. All the care they take creating images with visually stunning colour is often trashed with a click of a mouse and the parsing of a profile. The brilliance of creative photography is often lost in the indiscriminate process of automatic colour conversion.

So the question begs… How do we retain the full colour gamut of RGB for digital publishing and, at the same time, operate an effective CMYK workflow which produces visually rewarding results?

The easy answer to this problem is to have two sets of images. One set of vibrant RGB images for digital use and a duplicate set of colour corrected CMYK images for litho printing. Perhaps, the most important aspect to this challenge is to be wholly aware of the CMYK crocodiles snapping at your RGB canoe and take the necessary action to paddle towards the sunrise of digital and lithographic utopia in whichever way you see fit.

Poppy photo © JP Rowe