As a vital ingredient of design work, getting the colour right can be crucial and can substantially influence the resulting printed product. When printing colour the process is generally using the CMYK colour process, also known as a four colour process or even process colour. Exceptions to this are when a specific spot colour is required then the process for print is not CMYK but a specific spot colour ink. We even combine CMYK colour printing with Spot colour printing to create 5 colour (or more) printed jobs which use CMYK process and a Spot colour.
CMYK denotes the four inks used which are Cyan, Magenta, Yellow and Key (black). The CMYK print process is commonly described as ‘subtractive’ as when the inks are laid on the paper (paper is usually white), they “subtract” brightness from the white of the paper.
On a computer screen, the colour model is RGB not CMYK. The RGB colour model is said to be additive in which Red, Green, and Blue light are added together in various ways to reproduce a broad array of colours. The name of the model comes from the initials of the three additive primary colors, red, green, and blue. The different models can therefore mean that the same colour in the same document on screen can often look different when printed. Colours can be slightly darker or more subdued when printed from their on RGB screen counterparts. Professional design software will support designs in the different colour models and enable swapping between the colour models to fine tune colours for best results for the on screen or printed use.
If you are in the process of preparing files to print, it is always worth checking that the images are in CMYK . Should they be in RGB, you can use an image manipulation programme such as Adobe PhotoShop to convert them before printing.
If files are supplied to us for print in RGB, our printing press software will automatically convert the colour to CMYK. If your colour is not too critical this can be a satisfactory solution. A better option however is for you to convert from RGB to CMYK beforehand. this will allow you to identify and colours that have converted differently to how you would like them and enable you to adjust the brightness, contrast and gradation or even the colour values themselves.
We undertake a pre press check on files not prepared by ourselves and if we think there might be an issue with a colour, we let you know.
If consistency of colour is required, for example on a logo, it is useful to identify the CMYK values beforehand from a set of prescribed print swatches. Printed colour swatches provide specific values for each of the four CMYK colours and therefore provides a measure from which the printer can work from. Be aware however that there may still be some variation from printer to printer.
Variation printing colour can also occur depending on the printing process which can either be lithographic (with inks) or digital (with toners), paper quality and finish.
Should colour consistency throughout a brand be critical, often a pantone reference for a spot colour or colours is identified providing the greatest control over the finished printed output bearing in mind that spot colour printing can work out much more expensive than the CMYK equivalent. Different printing processes and even different machines using the same process are able to reproduce different ranges of colour due to the design and processing capability of the machine. The range of colours that can be reproduced by a machine is known as the colour Gamut. A wet printed proof is a reliable method of ensuring colour expectations are met and should a large run of printing be required and colour is critical then it may be is worth paying extra for.