add jjn and atkinson
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parent
2bada11da1
commit
b9c6cf1a07
4
main.go
4
main.go
@ -53,6 +53,10 @@ func main() {
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new = apply(i, simpleErrorDiffusion())
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case "floydsteinberg":
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new = apply(i, floydSteinberg())
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case "jjn":
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new = apply(i, jarvisJudiceNinke())
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case "atkinson":
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new = apply(i, atkinson())
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default:
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fmt.Printf("unknown ditherer option: %s\n", ditherer)
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os.Exit(2)
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60
quantizer.go
60
quantizer.go
@ -180,6 +180,66 @@ func floydSteinberg() quantizerFunction {
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}
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}
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func jarvisJudiceNinke() quantizerFunction {
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errMap := make(map[coord]float64)
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d := diffusion{
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divisor: 48.0,
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matrix: map[coord]float64{
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{x: 1, y: 0}: 7.0,
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{x: 2, y: 0}: 5.0,
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{x: -2, y: 1}: 3.0,
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{x: -1, y: 1}: 5.0,
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{x: 0, y: 1}: 7.0,
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{x: 1, y: 1}: 5.0,
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{x: 2, y: 1}: 3.0,
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{x: -2, y: 2}: 1.0,
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{x: -1, y: 2}: 3.0,
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{x: 0, y: 2}: 5.0,
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{x: 1, y: 2}: 3.0,
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{x: 2, y: 2}: 1.0,
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},
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}
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return func(x int, y int, c color.Color) color.Color {
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p := coord{x: x, y: y}
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l := luminence(c) + errMap[p]
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delete(errMap, p) // don't let the error map grow too big
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if l > 0.5 {
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applyError(d, l-1.0, p, errMap)
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return color.White
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}
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applyError(d, l, p, errMap)
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return color.Black
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}
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}
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func atkinson() quantizerFunction {
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errMap := make(map[coord]float64)
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d := diffusion{
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divisor: 8.0,
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matrix: map[coord]float64{
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{x: 1, y: 0}: 1.0,
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{x: 2, y: 0}: 1.0,
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{x: -1, y: 1}: 1.0,
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{x: 0, y: 1}: 1.0,
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{x: 1, y: 1}: 1.0,
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{x: 0, y: 2}: 1.0,
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},
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}
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return func(x int, y int, c color.Color) color.Color {
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p := coord{x: x, y: y}
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l := luminence(c) + errMap[p]
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delete(errMap, p) // don't let the error map grow too big
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if l > 0.5 {
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applyError(d, l-1.0, p, errMap)
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return color.White
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}
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applyError(d, l, p, errMap)
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return color.Black
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}
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}
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// That is, "relative luminance": https://en.wikipedia.org/wiki/Relative_luminance.
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// go's color library doesn't give any information on what "color space" the RGBA is derived from,
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// so we convert to Y'CbCr, which returns luminence directly as the Y component.
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