David Vanderson on wrote... | Anthony Thyssen wrote: | > David Vanderson on wrote... | > | Hello, | > | | > | Does anyone have a suggestion for how to select everything that's not a | > | specific color? | > | | > | For instance, in the following command I'm trying to make everything but | > | magenta transparent: | > | convert -channel "RGBA" -colorspace "rgb" in.png +matte -transparent | > | "magenta" -fill "black" -colorize "100%" -background "magenta" -flatten | > | -transparent "black" out.png | > | | > | This does work but seems overly complicated. I'm hoping there's a more | > | straightforward way. | > | | > There is currently no negated -opaque operator. | > You also do not need the -channel or the -colorspace options in the | > above. | > | > So the above basically uses the selected color as a mask to invert the | > result. | > | > An alturnative is to use the NEW change_mask composite operator.. | > Which I added to IM v6.3.4 | > http://www.imagemagick.org/Usage/compose/#changemask | > | > convert in.png \( +clone +matte -fill magenta -colorize "100%" \) \ | > -compose ChangeMask -composite out.png | > | > This compares each color in the in.png with another 'all magenta' image | > that is the same size, and makes anything that is the same transparent. | > | > That is what is magenta is cleared. | > | > To invert, compare the image to itself, but with the magenta colors | > changed, to anything else! | > | > convert in.png \( +clone -fill black -opaque magenta \) | > -compose ChangeMask -composite out.png | > | > The parts of the first (original) image that changed color (magenta | > areas) will be returned. | > | > | > You can check if your IM has this Alpha Composition method using... | > convert -list composite | grep ChangeMask | > | > It was added to allow changes from one frame to the next to be detected | > and simplified for a new GIF Animation Compression Optimization, | > "-layers OptimizeTransparency" to make animation file sizes smaller. | > http://www.imagemagick.org/Usage/anim_opt/#opt_trans | > | > It was also incorperated into the General GIF Optimizer operator... | > "-layers Optimize" | > http://www.imagemagick.org/Usage/anim_opt/#optimize | > | > | This is the best response I've ever gotten on any mailing list. Thank | you very much Anthony.
You can also try the IM Discussion forums. http://www.imagemagick.org/discourse-server/ Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]> ----------------------------------------------------------------------------- REALITY.SYS Corrupted - Unable to recover Universe ----------------------------------------------------------------------------- Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/ _______________________________________________ Magick-users mailing list [email protected] http://studio.imagemagick.org/mailman/listinfo/magick-users
