Editor Note: Section 18.92 draw:blue

The draw:blue attribute specifies together with the attributes draw:green and draw:red a non destructive filter for a linear transformation of the white balance of a pixel image. If any of these three attributes is specified, an offset is applied to each pixel of an image while is it rendered. The offsets for each color channel is given as a percentage in the range of -100% to +100%. These offsets is scaled to the range -2^bits to 2^bits, where bits is the number of bits reserved for each color channel within the image. If the resulting value is less then 0 it is set to 0 and if it is greater than the maximum possible value it is set to the maximum. Example: If the draw:blue attribute has the value 50% and and the blue color channel has 8 bits, then 128 is added to the blue color value of each pixel inside the image before it is rendered. If draw:red has the value -50% then 128 is subtracted. The draw:blue attribute specifies the offset for the blue color channel.