A basic understanding of colour in printing
Red, Yellow and Blue are the primary colours used when painting with oil and watercolours. These paints are produced from pigments and dyes. So what are RGB and CMYK colours and what's the difference between the two?
Nearly all scanners or digital cameras create images using three colours: Red, Green and Blue (RGB), these are the colours by which computers display images on screen - also known as the ADDITIVE PRIMARY colours.
The diagram on the right illustrates how Red, Green and Blue colours added together give white.
RGB is the method used for computer screen displays and is often the default setting for scanners and digital cameras.
Printing presses however, print full colour using SUBTRACTIVE PRIMARY colours.
CMYK is short for cyan, magenta, yellow, and key (black).
Also referred to as process colour or four colour.
All colours used in files for litho printing must be CMYK.
The diagram on the right illustrates how Cyan, Magenta and Yellow colours (primary colours) interact with each other to create the millions of colours needed for photographic reproduction and when added together in equal proportions give black.
In practice an extra Black (K) colour is added to enhance depth and for sharper text. Black made up from CMY can look more of a muddy brown and results in too much ink sitting on the paper.
Converting to CMYK for print
You will have more control over the appearance of your artwork if you convert all images from RGB to CMYK yourself. If we receive RGB images, we do a standard conversion to CMYK in Photoshop. This is done via the Image > Mode menu and selecting CMYK color.
When the RGB colours are converted to CMYK some change (usually “dulling” can occur). The resultant colours may not be exactly to your taste. If you make this mode change prior to supplying your graphics you may be able to adjust the settings to something you prefer.
Colour Profiles and ISO 12647
From proof to final print our colour-managed workflows ensure that your artwork prints as you intend it to using industry standard profiles. What you see on screen may be very different to what appears in print which is where the use of a standard colour profile is essential if colour reproduction is important to you.
An ICC profile created by the International Colour Consortium contains a set of data that is characterised by a standard colour space. This is to help keep colour as consistent as possible between various devices, such as computers, cameras, scanners and printers.
The current international standard used by the majority of printers and throughout Adobe Creative Suite is ISO 12647. Pagefast uses this colour profile to keep colour consistent between the printed proof that you see and the final print, unless different colour settings are required by the customer. Artwork supplied as generic CMYK is automatically converted to ISO 12647 colour space.
Settings should be set to the Europe General Purpose preset and then under CMYK the ISO 12647 should be selected. You may also see options for Coated FOGRA27, Coated FOGRA39, Uncoated FOGRA29, Web Coated FOGRA28 in front of the ISO 12647, these refer to the paper your artwork will be printed on. If your artwork is to be printed on uncoated stock you would use Uncoated FOGRA29. The European preset will generally default this to Coated FOGRA39 which is ideal for most work.
Please be aware that some of these options vary between different versions of Creative Suite and other graphic software. If in doubt, please contact us for further assistance.
Colour correct proofs
We can supply you with a CMYK colour correct proof on FOGRA approved paper before signing your work off for press.
Every proof is scanned and calibrated to ensure that every colour is represented faithfully on the proof. (Excludes Pantone/special colours)
Our proofer will also emulate certain finishes, again using different FOGRA profiles. For instance if your artwork is to be printed on an uncoated stock or matte laminated the proof can show a reasonable likeness to what your artwork will look like.
If your images are black and white, they should be supplied in greyscale, as this removes all colour information and ensures that your image is only printed using black. In Photoshop, the same as converting from RGB to CMYK, changing to Greyscale is done via the Image > Mode menu and selecting Grayscale.
To create a more dense black on solids a 40% tint of cyan is added. Black can look more like dark grey, or even washed out, when printed over a large area.
However, this method is not recommended on text, particularly body copy or any small type, nor any thin lines which should remain 100% black.
Spot colours and the Pantone colour reference system
The Pantone Colour reference system is the most widely-used method of identifying the exact specification of colours used in printing in the UK (although there are other reference libraries).
Most software packages have a selection of built-in colour libraries and the most popular is the Pantone Matching System or PMS. The Pantone Colour Formula Guide is used professionally to mix colours accurately to different types of paper.
Pagefast generally uses the standard PANTONE Solid Coated and Uncoated colour books when selecting spot colours. These can be used with CMYK process colours or on their own to create one, two or three colour work.
There are a large number of variables which can affect the colours used in your job. Generally it is much better to choose and use colours from printed swatches than to rely on the appearance of colours on a monitor.
Pantone colours can also look slightly different when emulated through the CMYK four-colour process so it cannot be guaranteed that the colour you view onscreen can be exactly reproduced in print.
things to note...
• Please take the time to prepare your files properly, we want you to be happy with your job.
• Always request a colour match proof to be sure that your work and any colours print as intended.
• We cannot be responsible for below par results if you supply low-resolution or RGB images.
• If in doubt do not hesitate to get in touch for further information or help.