[magick-users] Automagically determining font-color

[Fred Weinhaus]

I don't know of any published algorithm, but off the top of my head, 
I can think of two things.

Lets say the color you get it rgb(x,y,z) from IM where x,y,z are in 
the range 0-255 or 0-100%

1) you could make your text color the complement by replacing 
x->255-x, y->255-y, z->255-z
or likewise in percent.

or

2) you could take the color as a small swatch image and use -modulate 
100,100,0 to rotate the hue by 180 degrees to get the complement 
color, then get its rgb values.

for example:

convert -size 1x1 xc:"rgb(79,148,205)" -modulate 100,100,0 -format 
"%[pixel:p{0,0}]" info:

returns

rgb(205,136,79)

and

convert -size 1x1 xc:"rgb(31%,58%,80%)" -modulate 100,100,0 -format 
"%[pixel:p{0,0}]" info:

returns:

rgb(80%,53.0007%,31.0002%)




>Hello
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>
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>I was wondering if anyone knows how to calculate a legible font-color,
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>once I've determined the mean color of the image (for a title bar).
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>
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>I've experimented a bit with calculating the font color (white/black) for
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>when the title bar color is nearest a color in the 216 'safe' HTML color
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>table. But the result, though workable, to a degree, still leaves to be
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>desired, in that sometimes I really think the font color should be white
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>instead of black, and vice versa.
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>
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>So, is there perhaps an algorithm out there I'm unaware of? Or a refined
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>lookup table of some sort.