UNDERSTANDING COLOUR ISSUES !!!

Understanding the differences in Colour Display, Printing and Proofing is a complex, and confusing issue.

Computer screens, by default, make up the colours they display in RGB Mode (that is, every colour you see on your computer monitor is created out of differing values of Red, Green and Blue).
For this reason most of the standard software applications, or programs, supplied with your computer . . . such as Microsoft Word, Microsoft Powerpoint, Microsoft Publisher, Apple Works etc. use the RGB model for their colour palettes. This is usually ideal for displaying colour elements on screen and even printing out work on attached desktop Inkjet or Laser printers where the colour can be made-up quickly and smoothly from the three basic RGB colours.

However, both the Litho and Digital Printing processes used for Commercial printing use the
CMYK colour model . . . C = Cyan, M = Magenta, Y = Yellow, K = Black (K to avoid confusion with B for Blue). This is the reason why you will often have heard “Full Colour printing” referred to as “4-Colour Printing”. CMYK printing actually allows far more flexibility in colour usage and tonal variations. Litho and Digital Printing software will therefore attempt to automatically convert any supplied RGB work to the closest CMYK equivalent colours. This will, inevitably, result in some change occurring to the colour of the work you have seen displayed on your screen, or even printed-out on a desktop Inkjet or Laser printer. Some colours (or combinations of colours) will be affected more than others, and . . . depending on the actual software used to originally create or compose the work . . . in extreme cases may even change an RGB coloured image to print-out completely Black or Grey. For this reason, we always recommend that you select a CMYK colour-palette in your production software if this is option is available. If you have scanned images or logos that you are inserting into your document these should be checked in your photo-retouching software (such as Adobe Photoshop) and converted to CMYK before inserting them into your document.

We also suggest using a CMYK Black (ie a Black made-up of 40% Cyan and 100% Black) for any large areas of solid Black background . . . but NOT for BLACK TEXT . . . instead you must always use 100% Black for setting Black Text in anything other than for large Poster work.  

Colour balance and reproduction can also be affected by the resolution at which the original element was first created in and the way it reacts to differing printing processes. Work created by most Web-Designers and Web-software applications will have been produced exclusively to display QUICKLY on even the most basic of computer monitors. That is they will have been designed to download through your Modem to your computer screen at between 96 to 72 dpi (dots per inch) and in the “web-safe” colour palette mode of RGB. (Most standard computer monitors display at 72 dots per inch.)

Furthermore, by their nature, computer screens (like televisions) display their image with light projecting out of  the screen towards the eye of the viewer. Commercial printing will normally require images to have been produced at around 300dpi (dots per inch). Because our modern Litho or Digital printing machinery prints at a much higher resolution (between 2400 to 1270dpi), elements such as graphics or logos downloaded from web-sites will often pixelate or appear jagged or blurred when printed. And, unlike the images projecting outwards from your computer screen, the colours of the printed image will be produced by varying layers of ink printing downwards on top of the printed matter.

The complication doesn’t just end there though !!!! Different printing processes, and different printed materials, will also have an affect on the way your image displays after the printing process. Inkjet Printers spray ink from cartridges in one pass onto the paper; Digital Laser Printers lay down layers of Toner in several passes onto the paper; Litho Printing Presses print the Ink from four different plates onto the paper leaving blank minute layers where the edges of some colours will overlap over others so as not to compromise the join where two or more colours touch (known as “trapping”).

It is also essential to remember that the nature of modern printing processes, and the ever-changing make-up of both inks, paper-stocks, processing plates (often due to constantly changing technological and environmental requirements), means that it is not technically possible to guarantee exact colour matching of the same project reprinted at a later date.

At momentoprint we will always endeavour to advise on how all these differences, and pitfalls,
may affect the final printing of your project. However, because of the hugely varying number, and technical quality, of software applications, colour palettes and production techniques, it is technically impossible to accurately predict how close to the printed proof your project will finally print . . . we must ALWAYS advise that the printed proof is a Visual Guide only !!!!!

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