add floyd-steinberg

This commit is contained in:
David 2021-01-11 19:47:29 -05:00
parent b8b7ff7167
commit 2bada11da1
2 changed files with 42 additions and 8 deletions

View File

@ -51,6 +51,8 @@ func main() {
new = apply(i, bayerDithering(1, true))
case "simpleerror":
new = apply(i, simpleErrorDiffusion())
case "floydsteinberg":
new = apply(i, floydSteinberg())
default:
fmt.Printf("unknown ditherer option: %s\n", ditherer)
os.Exit(2)

View File

@ -122,28 +122,60 @@ func bayerDithering(level int, invert bool) quantizerFunction {
}
}
func applyError(diffusionMatrix map[coord]float64, divisor float64, quantError float64, currentPixel coord, errMap map[coord]float64) {
for c, i := range diffusionMatrix {
type diffusion struct {
matrix map[coord]float64
divisor float64
}
func applyError(diffusion diffusion, quantError float64, currentPixel coord, errMap map[coord]float64) {
for c, i := range diffusion.matrix {
target := coord{x: currentPixel.x + c.x, y: currentPixel.y + c.y}
errMap[target] = errMap[target] + (quantError * (i / divisor))
errMap[target] = errMap[target] + (quantError * (i / diffusion.divisor))
}
}
func simpleErrorDiffusion() quantizerFunction {
errMap := make(map[coord]float64)
diffusionMatrix := map[coord]float64{
d := diffusion{
divisor: 2.0,
matrix: map[coord]float64{
{x: 1, y: 0}: 1.0,
{x: 0, y: 1}: 1.0,
},
}
return func(x int, y int, c color.Color) color.Color {
p := coord{x: x, y: y}
l := luminence(c) + errMap[p]
delete(errMap, p) // don't let the error map grow too big
if l > 0.5 {
applyError(diffusionMatrix, 2.0, l-1.0, p, errMap)
applyError(d, l-1.0, p, errMap)
return color.White
}
applyError(diffusionMatrix, 2.0, l, p, errMap)
applyError(d, l, p, errMap)
return color.Black
}
}
func floydSteinberg() quantizerFunction {
errMap := make(map[coord]float64)
d := diffusion{
divisor: 16.0,
matrix: map[coord]float64{
{x: 1, y: 0}: 7.0,
{x: -1, y: 1}: 3.0,
{x: 0, y: 1}: 5.0,
{x: 1, y: 1}: 1.0,
},
}
return func(x int, y int, c color.Color) color.Color {
p := coord{x: x, y: y}
l := luminence(c) + errMap[p]
delete(errMap, p) // don't let the error map grow too big
if l > 0.5 {
applyError(d, l-1.0, p, errMap)
return color.White
}
applyError(d, l, p, errMap)
return color.Black
}
}