Difference between RGB and CMYK

19/02/08 – “We always get questions from clients in reference to web colors they view on screen and what they see in brochures and other print media.”

RGB and CMYK are the two most prominent and typical color 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 fledgling designer can vastly improve the quality of a project.

RGB (Red, Green, Blue) is the typical color space used by electronic displays, monitors, pda screens, etc. In RGB, images are created by combining red, green, and blue light. Process of addition can create millions of different colors 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 color model used by color 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 colors in a subtractive process using four colors or inks: cyan (blue), magenta (red), yellow, and black. Chances are your inkjet, bubblejet, or laser printer at home has a CMYK or CMYK variant setup.   There are many RGB colors 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 color 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 color 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 color settings. Also you can view some values on new models of CRT and Digital Monitors.
The RGB color model is an additive color model. Additive color models use transmitted light to display color. Monitors use the RGB color model. When you add red light, blue light, and green light together, so that the value of each component is 255, the color 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 color 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 color 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 blue ink colour)
M Magenta Ink (this is a 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.