Conversion to grayscale uses wrong formula

[rtrussell]

Currently the conversion to grayscale is using the formula:

Uint8 grayedColor=(rr+gg+bb)/3

This is wrong. When converting to grayscale, perceptual weighing must be applied (for example the eye is much less sensitive to blue than to green, so blue appears much darker when converted to grayscale). The most common formula used is that specified in CCIR 601, which is approximately:

0.30 * rr + 0.59 * gg + 0.11 * bb

or if you prefer to do it all in integers:

(30 * rr + 59 * gg + 11 * bb) / 100

There is much more detail available at Stack Overflow.

[nhurde]

OMG, never even thought about colors that way before. I will do some changes to see how better it looks now. Also, does the current method apply as a different graphic effect/shader or should I just get rid of it?

[rtrussell]

No harm leaving it as an option, I guess, but I can't think of any uses for it other than to provide compatibility with earlier versions of your software.