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RGB colour is generally a format used in digital imaging devices such as scanners, digital cameras and computers, and also in designing for web. Offset printing presses and digital printing machines however, print full colour images using a different set of colours to RGB. The colour process that forms the basis of printing is CMYK. This acronym stands for the four colours of pigment: Cyan, Magenta, Yellow and Black. It can also be referred to as “process colour” or “four colour process”. Combinations of these four colours creates the full range of colours that you see in printed material and results in a smooth, continuous tone. It is recommended that if you are producing material for print by a professional service such as ActsCo Printing, that you convert your images to CMYK before sending the print files. Doing this will allow you to tweak any images that do not convert well and have a different appearance to their RGB originals. Unfortunately, not all RGB colours will convert well to CMYK – these colours are said to be “out of the CMYK colour gamut”. To accommodate for this, you should convert your RGB images in your favourite imaging program (e.g. Photoshop) and check them against the original RGB image. It is at this stage that you can tweak the colours if you find that their appearance is dull or not as you expected. If you do not convert your images to CMYK before sending them to ActsCo, we will run a script in Adobe Acrobat that will convert them to CMYK, however we generally do not check the images after the conversion as this would be far too time consuming (especially to make any colour tweaks that might be necessary), so we recommend you convert your images before sending your files to us. Below is an example of colours that do not convert well from RGB to CMYK. |





