Digital photos are built of pixels. When you look at a digital photo on a computer screen or on a printed version of the photo you are really looking at millions of pixels each with a unique color and intensity. When put together all these pixels form the photo that you see. There are a few formats used to represent a pixel color – here are the common ones.
You have probably heard at least one of the following acronyms: RGB, CMYK and HSV. RGB is the most popular one with CMYK not lagging far behind. Each format is a different way to describe a pixel color. The same pixel can be represented in each of the three formats. Each format is commonly used in some applications.
Here is a description of each of these formats and their usage:
RGB – Red Green Blue: In RGB format each pixel color is represented as an addition of three primary colors: red, green and blue. Any color can be reproduced by mixing these three components in different ratios. RGB is most commonly used to represent colors that are displayed on compute screens. The reason is that RGB is an active format or in other words it describes colors as an addition of red green and blue light emitted from a light source such as a compute screen. A compute screen emits red blue and green light for each pixel in order to create the pixel color.
CMYK – Cyan Magenta Yellow Key: The CMYK format is used for representing pixels color on printed paper. The fourth component, key, is also know as the black component. Different colors are created when mixing the first three components CMY. Pure black however is hard to achieve with such mixing and for that reason black has a value of its own. The CMYK format is also aligned with how most color printers are implemented – they have one black cartridge and three color cartridges for cyan, magenta and yellow. The reason printers are implemented this way is that pure real black color is hard to reproduce by mixing three other colors. Opposite to RGB which works by mixing light emitted by a light source CMYK works by mixing the light not absorbed by ink on paper. CMYK is thus also known as passive while RGB is known as active.
HSV – Hue Saturation Value: The HSV format is used by many photo editing software and by most semi-professional and professional graphic designers and artists. The HSV format is more aligned with the way we see and describe colors. Hue defines the color – for example green, yellow, purple etc. Saturation defines how pure the color is– it varies from dark or faded color to the pure color for example a green hue can be 100% saturated – or a pure green or it can be 0% saturated or practically black. Value is the intensity or brightness of the color. A value can be 0% which means the color is not bright at all or is practically black or 100% which means the color is as illuminated and bright as it can possibly be. This format follows how we see and describe colors and for that reason it is used by photo editing software. When we see color we first describe what color we see (e.g. green) then we add how saturated it is (e.g. faded green) and then we add how bright or illuminated it is (e.g. bright faded green).