[magick-users] Re move Colors from GIF

[Fred Weinhaus]

Please explain what you mean by "remove"?  You must change the color 
to something, but it can be another color or transparent. Do you mean 
transparent? Do you mean black?

Also what do you mean by the range FFFFFF to 0000FF? This is the 
equivalent of white to blue, but this is ambiguous, since it includes 
FF00FF which is magenta. Are you saying that you only want to remove 
the blue channel or make all intensities of pure blue become black or 
transparent or make all saturations of pure blue become black or 
transparent.

The following will make the blue channel into black and then next one 
will make it transparent.

convert logo: -channel blue -threshold -1 -negate logo_bluechannel2black.png

convert logo: -channel blue -threshold -1 -negate -transparent black 
logo_bluechannel2none.png

The following will make all saturations of pure blue into black and 
the next one will make all intensities of blue into black

convert logo: -fx "u<=hsl(240,100%,50%)&&u>=hsl(240,0%,50%)?black:u" 
logo_bluesat2black.png

convert logo: -fx "u<=hsl(240,100%,50%)&&u>=hsl(240,100%,0%)?black:u" 
logo_blueint2black.png

But as you will see it changes all the colors and in the case of the 
logo: image, all are identical because the logo image has no pure 
shades of blue.

If you try the same on 
http://www.fmwconcepts.com/misc_tests/grad_wedge.png you will see 
differences.


>I need to remove all colors from/to from a gif  FFFFFF:0000FF I am having
>trouble with the commands can someone please help!
>--