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I'm trying to convert all non-transparent pixels of an image to white using the geq filter in ffmpeg:
ffmpeg -y -i in.png -vf "format=rgba,geq='r=if(lt(alpha(X,Y),10),255):g=if(lt(alpha(X,Y),10),255):b=if(lt(alpha(X,Y),10),255):a=alpha(X,Y)'" x.png
But ffmpeg is giving me black pixels instead of white. Any ideas what is going on?
in.png:
out.png:
The two operand if expression returns 0 if the condition isn't met. You need the three operand version.
if(lt(alpha(X,Y),10),255,p(X,Y))
ffmpeg -y -i in.png -vf "format=rgba,geq='r=if(gt(alpha(X,Y),128),255,0):g=if(gt(alpha(X,Y),128),255,0):b=if(gt(alpha(X,Y),128),255,0):a=if(gt(alpha(X,Y),250),255,0)'" x.png && open x.png
Sep 24, 2018 at 16:06