Legacy ImageMagick Discussions Archive

I have a tiff file that is mostly white with some red lines and characters. There is just one red color. I need to change this to black with 80% shading. (Or what Corel Draw would call 80% shading) All of my attempts to change the color to black produce a totally black page. Does someone have a recommendation? My attempts are below.

convert +level-colors 'rgb(0,0,0)', 3251-1909.tif Black3251-1909.tif

convert 3251-1909.tif +level 0%,50% Black3251-1909.tif

convert 3251-1909.tif +level-colors black, Black3251-1909.tif

I'm not clear on exactly what you want. If you want to turn all red pixels black: I don't what "black with 80% shading" is. Perhaps it corresponds to 20% in each of the RGB channels, which is quite dark.

Yes, I'm trying to change all red pixels black. Since red is the only color it would also be to change all colored pixels black. The red is rgb(232,17,45) if that makes a difference.

This will be a print file for a laser etching machine. The 80% is a dot matrix pattern with 80% of coverage. Corel Draw calls it shading

I tried those two options but still get a completely black page. The format of the file is:
360 DPI TIFF, 1944 x 1500 pixels, 24 bit depth, Uncompressed, Resolution Unit 1

Thanks for looking at this.

Okay. To IM, "red" means "rgb(255,0,0)". But your colour is "rgb(232,17,45)". So:

or use red with -fuzz XX%