Meh, I don't think screen mode really makes sense in FP anyway. It is meant is a hack to simulate what adding should do when you aren't working with linear images. It was always a bit of a weird 8 bit hack, and it breaks counterintuitively with anything outside the 0-1 range. You expect that screening a bright thing with a bright thing should be very bright...
a = .5, b = .5 result = (.5+.5) - (.5*.5) = .75 result is brighter than either input, makes sense. a=1.0, b=1.0 result = (1 + 1) - (1*1) = 1 "maximum brightness" a = 4.0, b = 4.0 result = (4 + 4) - (4*4) = -8 WTF, it turned negative?! I don't know that it makes sense to implement screen when we are assuming linear, potentially HDR images. Once you have everything linear, you just use an add to get the effect of adding two things. On Wed, Jul 11, 2012 at 10:19 PM, Stefan Stavrev <[email protected]> wrote: > You are fast! :D > > Ok I think I can do this for the other operations. > > Just to share another example for the blending mode "Screen", > whose formula is: f(a,b) = (a+b) - (a*b). > _______________________________________________ Oiio-dev mailing list [email protected] http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
