Legacy ImageMagick Discussions Archive

I have a PNG image containing only two colors in its palette. I need to change these two colors from certain rgb values to certain other rgba values. I can easily achieve this, but it is very slow. I think the time is spent rebuilding the color table. Is there a fast way to poke new values into the color table?

If not, I'll take the 10x increase in file size for the 10x speedup. -type TrueColorMatte still leaves me in indexed palette mode. -define png:color-type=6 does take me to true RGBA. What does -type do?

-type is a hint to the image coder. PNG coder has many other options and generally ignored the type. It did no tuse to do that but now does in a recent expansion of the coder. Specifically with generating smaller palette PNG images.

Glennrp is the developer.

As for your problem, assuming it is exactly two colors and no gradient. try... The lighter color will map to blue, the darker to red.