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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package color
import (
"testing"
)
func delta(x, y uint8) uint8 {
if x >= y {
return x - y
}
return y - x
}
// Test that a subset of RGB space can be converted to YCbCr and back to within
// 1/256 tolerance.
func TestRoundtrip(t *testing.T) {
for r := 0; r < 255; r += 7 {
for g := 0; g < 255; g += 5 {
for b := 0; b < 255; b += 3 {
r0, g0, b0 := uint8(r), uint8(g), uint8(b)
y, cb, cr := RGBToYCbCr(r0, g0, b0)
r1, g1, b1 := YCbCrToRGB(y, cb, cr)
if delta(r0, r1) > 1 || delta(g0, g1) > 1 || delta(b0, b1) > 1 {
t.Fatalf("r0, g0, b0 = %d, %d, %d r1, g1, b1 = %d, %d, %d", r0, g0, b0, r1, g1, b1)
}
}
}
}
}
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