mirror of
https://github.com/nxshock/colorcrop.git
synced 2025-07-02 00:23:44 +05:00
71 lines
1.9 KiB
Go
71 lines
1.9 KiB
Go
package colorcrop
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import (
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"image/color"
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"math"
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)
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// comparator is a function that returns a difference between two colors in
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// range 0.0..1.0 (0.0 - same colors, 1.0 - totally different colors).
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type comparator func(color.Color, color.Color) float64
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// CmpEuclidean returns Euclidean difference of two colors.
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//
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// https://en.wikipedia.org/wiki/Color_difference#Euclidean
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func CmpEuclidean(color1 color.Color, color2 color.Color) float64 {
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const maxDiff = 113509.94967402637 // Difference between black and white colors
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r1, g1, b1, _ := color1.RGBA()
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r2, g2, b2, _ := color2.RGBA()
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return math.Sqrt(distance(float64(r2), float64(r1))+
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distance(float64(g2), float64(g1))+
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distance(float64(b2), float64(b1))) / maxDiff
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}
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// CmpRGBComponents returns RGB components difference of two colors.
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func CmpRGBComponents(color1 color.Color, color2 color.Color) float64 {
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const maxDiff = 765.0 // Difference between black and white colors
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r1, g1, b1, _ := color1.RGBA()
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r2, g2, b2, _ := color2.RGBA()
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r1, g1, b1 = r1>>8, g1>>8, b1>>8
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r2, g2, b2 = r2>>8, g2>>8, b2>>8
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return float64((max(r1, r2)-min(r1, r2))+
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(max(g1, g2)-min(g1, g2))+
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(max(b1, b2)-min(b1, b2))) / maxDiff
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}
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// CmpCIE76 returns difference of two colors defined in CIE76 standart.
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//
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// https://en.wikipedia.org/wiki/Color_difference#CIE76
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func CmpCIE76(color1 color.Color, color2 color.Color) float64 {
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const maxDiff = 149.95514755 // Difference between blue and white colors
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cl1, ca1, cb1 := colorToLAB(color1)
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cl2, ca2, cb2 := colorToLAB(color2)
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return math.Sqrt(distance(cl2, cl1)+distance(ca2, ca1)+distance(cb2, cb1)) / maxDiff
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}
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func distance(x, y float64) float64 {
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return (x - y) * (x - y)
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}
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// min is minimum of two uint32
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func min(a, b uint32) uint32 {
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if a < b {
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return a
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}
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return b
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}
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// max is maximum of two uint32
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func max(a, b uint32) uint32 {
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if a > b {
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return a
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}
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return b
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}
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