RGB is the acronym for the additive color system formed by the initials of the colors in English red, Green and blue, which means in Portuguese, respectively, Red, Green and Blue.
The RGB luminous color system (also known as light-color) is used in objects that emit light, such as computer and television monitors, digital cameras, the scanner, between others.
On the other hand, the subtractive color pattern called CMYK is used in printers, formed by the primary pigments Cyan (Cyan), Magenta (Magenta) and yellow (Yellow) and yet, the black (Black).
Colors are obtained by mixing the three primary colors, in determined amounts. Each of the colors obtained are framed on a scale ranging from 0 to 255. When the mixture of the three colors is at the minimum value (0, 0, 0), the result is the black color. When it is at the maximum (255, 255, 255), the color is white.
The variation between minimum values corresponds to dark tones and between maximum values, tones are more intense, lighter.