[SOLVED] Getting complementary color from a given color

[cubancigar11]

Hi!

I am trying to find the two colors from an image: the dominant one, and its complementary. From viewtopic.php?f=1&t=12878, I am able to get the dominant color using following command:

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convert img.png -colors 16 -depth 8 -format "%c" histogram:info:|sort -rn|head -n 1|grep -oe '#[^\s]*'

But I don't want to process the same image again to get the complementary. Is it possible?

PS: I am not looking for exact values for colors.

[snibgo]

The complement of a colour is (usually) the same lightness and saturation, with the hue rotated by 180 degrees, or 50%. We can do this with "-modulate":

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convert xc:red -modulate 100,100,0 txt:

For "red", use any color you like, eg

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convert xc:srgb(10%,20%,30%) -modulate 100,100,0 txt:

[cubancigar11]

Thanks. I am assuming there is no way to print it in #rrggbb format instead of #rrrrggggbbbb. But that is not a problem. Thanks again.

[fmw42]

add -depth 8 to snibgo's solution.

convert xc:"srgb(10%,20%,30%)" -modulate 100,100,0 -depth 8 txt:

[cubancigar11]

Thanks! That does it!

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% convert xc:'#004d09' -modulate 100,100,0 -depth 8 txt:
# ImageMagick pixel enumeration: 1,1,255,srgb
0,0: ( 77,  0, 68)  #4D0044  srgb(77,0,68)