There are lots of resources on the internet about different dot types and screen angles, for example on The Print Guide.ĬMYK is not exclusive to digital and lithographic printing – in fact CMYK colour separations, or approximations where they are replaced with slightly or wildly different colours, are common in screen printing, risograph printing and even photo etching. When two colors are less than 30º apart there is a risk of moiré. A standard combination of angles is Yellow at 0° or 90°, Black at 45°, Magenta at 75° and Cyan at 15°. The distribution, size and angles of these dots matter. Activating CMYK channels in Adobe Photoshop Original image from ‘200 House Plants in Colour’, first published 1968 by Zomer & Keuning. A picture and close up showing CMYK halftones. This can also create hues of warm and cool black. This is solid black overprinted with a combination of one or all other CMYK primary colours. In order to achieve a real, dark black, designers and printers usually specify a rich black. When you look closely you can determine the dot sizes and angles at which they are printed. The four colours are printed in detailed patterns of differently sized dots to create the illusion of all colours. Modern printers like for example the HP Indigo additionally use orange, violet and white.Īll visible colours are made up of cyan, magenta, yellow and black. Adobe Photoshop Colour Picker for web colours, showing #0000FF In Printĭigital printing and offset lithographic printing predominantly use CMYK for standard four-colour printing. F is the most light, while 0 represents the least: so #ffffff equals white, and #000000 equals black. The first two characters stand for red, the third and fourth for green, and the last two for blue. A hexadecimal is made up of a hashtag and six character. Hexadecimals, which you may have come across in web design, are basically shorthand for RGB. They will convert and output it as CMYK, but this will usually lead to duller colours. In order to have control over your printed output, always convert your images and files before printing – ideally while before designing! You can check and change your colour space in Adobe Photoshop under Image > Mode. When you import images from your phone, camera or a scanner, they will by default be set to RGB. Most printers, including your standard home printers, can interpret RGB data. We will take a quick look at channels a little bit further down. It has the added benefit of reducing your file size, because it contains one colour channel less. This means that RGB is used for anything displayed on a screen, so if you are preparing images and colours for websites, they should be in this mode. The different colors we see are due to different combinations and intensities of these three primary colors. On ScreenĪ monitor or TV screen generates three colors of light: red, green and blue. The K in CMYK stands for Key, referring to the key colour or plate. The combination of its primary colours, Cyan, Magenta and Yellow, results in ‘black’ – or rather, a dark, muddy brown. This is because the RGB model is based on three light rays which are projected onto a surface.ĬMYK, on the other hand, is a subtractive colour space. The overlap of its three primary colours, Red, Green and Blue, results in white. It is meant as a small guide to help you decide when to use which colour mode and how to go about mixing the perfect shade in a print workshop. It will then touch on mixing colours in the printmaking and letterpress workshops at LCC. This post briefly introduces the two colour modes CMYK and RGB before moving on to the Pantone Matching System.
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