Topic: What method is used for grayscale conversion?

When I convert from RGB to Grayscale with the "Convert to Grayscale" function, what method is it using to convert? Is it (R+G+B)/3, which is the color channel average,  or is it the method used by get the Y channel in YCbCr when converting from RGB to YCbCr (which I believe is approximately R*0.3 + G*0.6 + B*0.1)?

And if in fact the standard grayscale conversion does not do the conversion according to color channel average, is there another function in IA that I could use to in fact do color channel average?

2

Re: What method is used for grayscale conversion?

It uses the weights of the Y channel in YCbCr as you suggest, and additionally the conversion happens in linear space and not in monitor gamma space (depending on your choice in the "Set image gamma" dialog).

The only way to get a simple average would be to use the Script feature and make a script where the pixels are computed as

(SrcBitmap[0][x,y] + SrcBitmap[1][x,y] + SrcBitmap[2][x,y]) / 3;
Michael Vinther

> software developer <