Am Sonntag, den 01.03.2015, 19:32 -0800 schrieb David Vincent-Jones: > I am confused by the operation of the channel mixer. > If I open the mixer and look at the Red channel the 'red' value is nominally > set at 1 ... if I now move the red slider to a lower level I would expect > that > the red values are diminished over the entire range but what appears to occur
What exactly do you mean by "dimished over the entire range"? That the histogramm retains its shape, but the height is reduced at every value by the same fraction? I'm having trouble imaging how this could work. A certain red value would get less populated (say by a factor of 2), but how should dt decide which pixels to discard/to desaturate in red and others not? > is that red values are minimized from the high end of the scale leaving the > low end untouched. If I push the red value down to .500 then the entire red > section of the histogram is bunched in exactly 1/2 of the scale. > > I am not sure at all what the intention is with this module when used with > values < 1. I'm guessing here: but isn't this supposed to be some sort of matrix multiplication? So: red(new) = c_rr * red(old) + c_rg * green(old) + c_rb * blue(old) (c_ij are the specific coefficients for mixing the channels; similar equations hold for the other colours; calculation done for every pixel) Regards, Oliver ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Darktable-users mailing list Darktable-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/darktable-users
