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Difference between RGB and CMYK Colours

“We always get questions from clients in reference to web colours they view on screen and what they see in brochures and other print media.”

RGB and CMYK are the two most prominent and typical colour spaces / formats / models used in the world of design. In print, web, or digital media, a basic understanding of what the differences are, means a designer can vastly improve the quality of a project and the client can understand the colour matching limitations.

RGB (Red, Green, Blue) is the typical colour space used by computer monitors, mobile phones and televisions. In RGB, images are created by combining red, green, and blue light. Process of addition can create millions of different colours by using varying concentrations of the primaries. So when designing a website, web banner, buttons, e-newsletter, etc., your images and files should be set to this profile. Chances are any image you receive will be RGB by default, but it’s always a good practice to check.


CMYK is the primary colour model used by colour printers. So for flyers, brochures, advertising, newsletters, direct mail pieces, etc., a CMYK profile may provide better quality results or a better expectation of what your results will be. CMYK creates different colours in a subtractive process using four colours or inks: cyan (blue), magenta (red), yellow, and black. Chances are your inkjet or laser printer at home has a CMYK or CMYK variant setup. There are many RGB colours that CMYK printers cannot reproduce. Something that looks good on the monitor may not retain that quality in the printed piece.

Why Colours Look Different

RGB System – Screen Viewing Only!

RGB colour system is only suitable for screen reproduction such as LCD and CRT computer monitors and TV screens. This is not suitable colour matching for printing or to colour match from, as each screen may represent colours differently. What may look fine on one screen, may be look completely different on another. This can be due to a number of reasons, whether it be due to individual screen settings such as brightness and contrast or even may be due to different monitor manufactures; i.e. Sony or LG.

The red, green, and blue components are the amounts of red, green, and blue light that an RGB colour contains and are measured in values ranging from 0 to 255. To see these values, open a drawing program on your computer and delve deep into the colour settings. Also you can view some values on new models of CRT and Digital Monitors.
The RGB colour model is an additive colour model. Additive colour models use transmitted light to display colour. Monitors use the RGB colour model. When you add red light, blue light, and green light together, so that the value of each component is 255, the colour white displays. When the value of each component is 0, the result is pure black.

CMYK/Process – Digital printing

The CMYK, also known as Process colours are generally used in digital printing for signage. CMYK refers to the four colours used; Cyan, Magenta, Yellow and Black to generate a colour. It is these four colours which are mixed together to make up other colours, much the same principal to how paint is colour matched.

One thing to note is that CMYK colours may not look identical to physical colours due to the restriction to the number of colours CMYK can reproduce and that Inks perform differently. For example, orange is very hard to reproduce, and can look very muddy in when printed digitally. We take care to register all images with our four colour bars applied to all printing we do. In this manner, the production crew can quickly and visually check the print at different stages. If a final colour is not accurately made, there is little we can do. It is a technology thing.

The CMYK colour model defines colour using the following components:
C Cyan Ink (this is a light blue ink colour)
M Magenta Ink (this is a hot pink ink colour)
Y Yellow (yellow ink)
K Black (Black ink, the character ‘k’ is used so as not to get confused with the ‘b’ in RGB. RGB was invented first we believe.)

The cyan, magenta, yellow, and black components are the amounts of cyan, magenta, yellow, and black ink that a CMYK colour contains and are measured in percent from 0 to 100.
The CMYK colour model is a subtractive colour model. Subtractive colour models use reflected light to display colour. Printed materials are produced using the CMYK colour model. When you combine cyan, magenta, yellow, and black, so that the value of each component is 100, the result is black. When the value of each component is 0, the result is pure white.



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