add floyd-steinberg
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parent
b8b7ff7167
commit
2bada11da1
2
main.go
2
main.go
@ -51,6 +51,8 @@ func main() {
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new = apply(i, bayerDithering(1, true))
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case "simpleerror":
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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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default:
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fmt.Printf("unknown ditherer option: %s\n", ditherer)
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os.Exit(2)
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44
quantizer.go
44
quantizer.go
@ -122,28 +122,60 @@ func bayerDithering(level int, invert bool) quantizerFunction {
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}
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}
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func applyError(diffusionMatrix map[coord]float64, divisor float64, quantError float64, currentPixel coord, errMap map[coord]float64) {
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for c, i := range diffusionMatrix {
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type diffusion struct {
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matrix map[coord]float64
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divisor float64
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}
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func applyError(diffusion diffusion, quantError float64, currentPixel coord, errMap map[coord]float64) {
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for c, i := range diffusion.matrix {
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target := coord{x: currentPixel.x + c.x, y: currentPixel.y + c.y}
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errMap[target] = errMap[target] + (quantError * (i / divisor))
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errMap[target] = errMap[target] + (quantError * (i / diffusion.divisor))
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}
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}
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func simpleErrorDiffusion() quantizerFunction {
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errMap := make(map[coord]float64)
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diffusionMatrix := map[coord]float64{
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d := diffusion{
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divisor: 2.0,
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matrix: map[coord]float64{
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{x: 1, y: 0}: 1.0,
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{x: 0, y: 1}: 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(diffusionMatrix, 2.0, l-1.0, p, errMap)
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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(diffusionMatrix, 2.0, l, p, errMap)
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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 floydSteinberg() quantizerFunction {
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errMap := make(map[coord]float64)
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d := diffusion{
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divisor: 16.0,
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matrix: map[coord]float64{
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{x: 1, y: 0}: 7.0,
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{x: -1, y: 1}: 3.0,
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{x: 0, y: 1}: 5.0,
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{x: 1, y: 1}: 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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