Explaining the differences and when to use each colour model – CMYK, RGB, HEX, Pantone Colour System.
You’ve decided to decorate your room and suddenly find your wall covered in a variety of roughly painted squares of colour and you still can’t decide which looks perfect. Getting the colour exactly right when designing and producing your own literature can be a headache. With such a range of hues to choose from, adding colour to a leaflet or poster can be a long job with many variations!
Having eventually found the right shade of pink on your screen, you suddenly find it changes when converted to your web page or when printed it becomes a muddy shade of orange! This article explains what goes wrong and how to avoid the problems when the wrong colour model is used.
The quick answer is that you have used the wrong colour model in the wrong place.
The specification for a colour to be printed is different to the specification a web designer will need to match the same colour. Colours have to be specified to achieve the right shade and depth. The difference between blue and purple or red and orange is often borderline. The colour one person calls orange another will describe as yellow.
Below is a simple explanation of the colour models and where they should be used.
‘CMYK’ is the standard colour model for Four Colour printing.
The use of Cyan, Magenta, Yellow and Black ink can create almost any colour imaginable and prints high quality photographic or graphic images. This is called a ‘subtractive” process. This means as the more ink added the darker the image becomes. i.e. white paper is the base and ink is added in order of Cyan, Magenta, Yellow and finally black so darkening the final result.
Resulting colours are made up from a percentage of each of the four colours
Files for four colour printing should always be submitted in CMYK.
‘RGB’, the colour model all screens use to create visual colour.
Red, Green, and Blue are the colours that create light. When combined together in different percentages, create the spectrum of colours based on what the human eye can perceive. Far more than we are able to reproduce in print. All colours are represented by a combination of numbers each ranging between 0 and 255.
The method here is ‘Additive’. No light (255) as in a black screen and as light is introduced the colours brighten until all three lights are brought together and create white light (0)!
RGB is also used in photography and scanning and is device dependant. Meaning, depending on the quality of the equipment RGB values can change slightly.
Don’t send files to your printer in RGB, your results will not be as you hope or you may incur costs from the printer for amending the files.
When working in Photoshop on photographic/illustrative files, work in RGB and convert when finished to CMYK.
‘Hexadecimal’ colour model is specifically for the web. You will find the ‘HEX’ code buried in the HTML code.
Web colours can be specified using RGB but they are converted to the Hexadecimal model which is more HTML friendly. All codes begin with a ‘#’.
At one time there were only 256 basic web safe colours but now with 16 and 24 bit (Truecolour) web safe colours are now almost practically forgotten. However problems do occur with inconsistency.
Specify colours using ‘Hex” for your web designer – he will love you!
‘Pantone Colour Matching system’ is a standardised system to ensure once a colour is specified it has a universal code for perfect match when printed.
‘Special’ colours are mixed using 13 base pigments (15 including black and white). Most Pantone colours are beyond the CMYK capabilities and although today conversions exist for all pantone colours the CMYK equivalent can vary considerably. There are specifications for printing each colour on uncoated and coated paper as different paper will produce different results depending on the porosity. Pantone also supply fluorescents and metallic colours. When using a special or ‘spot’ colour it can be alone or alongside the standard CMYK print process.
Trial and error in matching colours can be irritating and even the right colour can slightly vary with different print suppliers. When colour matching is crucial send a sample for the printer to match to, it helps them keep you happy!