Adobe Photoshop Tutorials

Understanding the difference between RGB mode and CMKY mode.

RGB Mode. Scanned photos and images from a digital camera and pictures created in Photoshop are normally in RGB. The colour contained in these images is split by the three channels – Red, Green and Blue.

Every Pixel in an RGB image is assigned an intensity value ranging from the following numbers 0 – 255, by increasing the values it makes the colours brighter.

The values of the Red, Green and Blue. If all the values are zero then this would mean it would be black, and if all the values where 255 this would then mean the colour would be white. If you had intermediate values such as Red 130, Green 130 and Blue 130 this would mean that the colour would be grey.

Colour Editing involves adjustments to all three channels, not just one. For example, if you increase the intensity of a red you must also reduce the green and blue values.

CMKY Mode. Designers working for printers mostly opt for CMYK mode, which converts the colour channels to match those of the printing process. The range of colours available in CMYK mode is a lot less than in RGB mode. CMYK mode also simulates the limitations of ink on paper when printing, so it’s always best to make all your colour adjustments in RGB.

How does CMYK work? Nearly every commercial printing presses produce colour by laying down cyan, yellow, magenta and black ink’s (black is the key colour for any printing).

When you are creating and editing CMYK colours this involves entering values between 0 which is no ink at all, and 100 which produces solid ink.

Contrary to RGB mode, increasing the intensity of a CMYK value makes the colour darker, and not brighter. Not very many printing presses can copy with all four inks printing at 100%.