# Pipette ## RGB Color Model

In the RGB color space a color is defined by their shares or parts of red (R), green (G) and blue (B). It is an additive color model, in which the colors are achieved by mixing the respective shares. This color space is used for systems with emitting light, such as monitors.

## Forms of Representation

Depending on the purpose, the shares are notified in percentage (0 to 1 or 0% to 100%), absolute values (par example 0 to 255) or hexadecimal (typically 00 to FF). The hexadecimal notation in the form #RRGGBB is primarily known through HTML and CSS, where also an abbreviated form #RGB is allowed if both hexadecimal digits are the same (for example #FFF for #FFFFFF or #A12 for #AA1122). Above that, TColor uses a special form of representation: Here the RGB components are calculated into a single number in order to express a color.

If all shares are zero (#000000) the color is black, if all shares are maximum (#FFFFFF), the color is white. In between these two values, there are all the other colors. Gray (see table with gray values) from white to black would arise if all of the three colors are available in an equal share (for example #131313 or #444444), a pure red arises, for example, only by a red portion (# FF0000), a pure yellow by the mixture of red and green (#FFFF00).

## Number of representable Colors

In the hexadecimal notation #RRGGBB, a maximum of 16777216 different colors can be expressed, since we are working with 8 bits per channel (0 to 255). When using 16 bits per channel (0 to 65535), 281 trillion different colors are possible; this is used, for example, by the image formats 16-bit TIFF and 16-bit PNG. Also if we use the percentage notation, we can save any number of color nuances by just using any number of decimal places. However, this will only be necessary in special cases, since human perception only allows a distinction to be made between around half a million color nuances.

The program pipette provides the hexadecimal notation and the percentage and absolute values automatically. For the hexadecimal notation see "HEX" in the first row, the absolute values you can find in the row "RGB" and the percentages in the line "RGB%".