If you set Mode to WEIGHTED, you may also set the values of Weight1, Weight2, and Weight3. These "weights" are used to determine how much influence the values of the red, green, or blue pixels will have on the reduction. For example, if Weight1 (red) = 255, Weight2 (green) = 0, Weight3 (blue) = 0, the whole reduction will depend on the value of the red pixels. The green and blue pixel values will have "no weight".

Setting Mode to GRAYSCALE gives the most weight to the value of green. This optimizes for the perception of the human eye, in which blue is the hardest color to see, and therefore requires the least weight.

A Mode of AVERAGE gives equal weight to all three pixel values.

Here are the formulas used by the three different reduction methods:

• GRAYSCALE: value = (red*77 + green*151 + blue*28)/256;
• AVERAGE: value = (red + green + blue)/3;
• WEIGHTED: value = (red*w1 + green*w2 + blue*w3)/(w1 + w2 + w3);

Value from ImGearBitonalReductionModes enumeration.