private static ColorMoment Bottom(Box cube, int direction, ColorMoment[, , ,] moment)
{
switch (direction)
{
case Alpha:
return (-moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMaximum, cube.BlueMaximum] +
moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMaximum] +
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMaximum] -
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMaximum]) -
(-moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMaximum, cube.BlueMinimum] +
moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMinimum] +
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMinimum] -
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMinimum]);
case Red:
return (-moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMaximum] +
moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMaximum] +
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMaximum] -
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMaximum]) -
(-moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMinimum] +
moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMinimum] +
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMinimum] -
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMinimum]);
case Green:
return (-moment[cube.AlphaMaximum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMaximum] +
moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMaximum] +
moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMaximum] -
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMaximum]) -
(-moment[cube.AlphaMaximum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMinimum] +
moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMinimum] +
moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMinimum] -
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMinimum]);
case Blue:
return (-moment[cube.AlphaMaximum, cube.RedMaximum, cube.GreenMaximum, cube.BlueMinimum] +
moment[cube.AlphaMaximum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMinimum] +
moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMinimum] -
moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMinimum]) -
(-moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMaximum, cube.BlueMinimum] +
moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMinimum] +
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMinimum] -
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMinimum]);
default:
return new ColorMoment();
}
}
private static float CalculateVariance(ColorMoment[, , ,] moments, Box cube)
{
ColorMoment volume = Volume(cube, moments);
return(volume.Variance());
}
private static CubeCut Maximize(ColorMoment[, , ,] moments, Box cube, int direction, byte first, byte last, ColorMoment whole)
{
var bottom = Bottom(cube, direction, moments);
var result = 0.0f;
byte?cutPoint = null;
for (var position = first; position < last; ++position)
{
var half = bottom + Top(cube, direction, position, moments);
if (half.Weight == 0)
{
continue;
}
var temp = half.WeightedDistance();
half = whole - half;
if (half.Weight != 0)
{
temp += half.WeightedDistance();
if (temp > result)
{
result = temp;
cutPoint = position;
}
}
}
return(new CubeCut(cutPoint, result));
}
private static ColorMoment Volume(Box cube, ColorMoment[, , ,] moment)
{
return (moment[cube.AlphaMaximum, cube.RedMaximum, cube.GreenMaximum, cube.BlueMaximum] -
moment[cube.AlphaMaximum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMaximum] -
moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMaximum] +
moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMaximum] -
moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMaximum, cube.BlueMaximum] +
moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMaximum] +
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMaximum] -
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMaximum]) -
(moment[cube.AlphaMaximum, cube.RedMaximum, cube.GreenMaximum, cube.BlueMinimum] -
moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMaximum, cube.BlueMinimum] -
moment[cube.AlphaMaximum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMinimum] +
moment[cube.AlphaMinimum, cube.RedMaximum, cube.GreenMinimum, cube.BlueMinimum] -
moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMinimum] +
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMaximum, cube.BlueMinimum] +
moment[cube.AlphaMaximum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMinimum] -
moment[cube.AlphaMinimum, cube.RedMinimum, cube.GreenMinimum, cube.BlueMinimum]);
}
private static CubeCut Maximize(ColorMoment[, , ,] moments, Box cube, int direction, byte first, byte last, ColorMoment whole)
{
var bottom = Bottom(cube, direction, moments);
var result = 0.0f;
byte? cutPoint = null;
for (var position = first; position < last; ++position)
{
var half = bottom + Top(cube, direction, position, moments);
if (half.Weight == 0) continue;
var temp = half.WeightedDistance();
half = whole - half;
if (half.Weight != 0)
{
temp += half.WeightedDistance();
if (temp > result)
{
result = temp;
cutPoint = position;
}
}
}
return new CubeCut(cutPoint, result);
}
private static Box[] SplitData(ref int colorCount, int maxColors, ColorMoment[, , ,] moments)
{
--colorCount;
var next = 0;
var volumeVariance = new float[maxColors];
var cubes = new Box[maxColors];
cubes[0].AlphaMaximum = MaxSideIndex;
cubes[0].RedMaximum = MaxSideIndex;
cubes[0].GreenMaximum = MaxSideIndex;
cubes[0].BlueMaximum = MaxSideIndex;
for (var cubeIndex = 1; cubeIndex < colorCount; ++cubeIndex)
{
if (Cut(moments, ref cubes[next], ref cubes[cubeIndex]))
{
volumeVariance[next] = cubes[next].Size > 1 ? CalculateVariance(moments, cubes[next]) : 0.0f;
volumeVariance[cubeIndex] = cubes[cubeIndex].Size > 1 ? CalculateVariance(moments, cubes[cubeIndex]) : 0.0f;
}
else
{
volumeVariance[next] = 0.0f;
cubeIndex--;
}
next = 0;
var temp = volumeVariance[0];
for (var index = 1; index <= cubeIndex; ++index)
{
if (volumeVariance[index] <= temp) continue;
temp = volumeVariance[index];
next = index;
}
if (temp > 0.0) continue;
colorCount = cubeIndex + 1;
break;
}
return cubes.Take(colorCount).ToArray();
}
private static bool Cut(ColorMoment[, , ,] moments, ref Box first, ref Box second)
{
int direction;
var whole = Volume(first, moments);
var maxAlpha = Maximize(moments, first, Alpha, (byte)(first.AlphaMinimum + 1), first.AlphaMaximum, whole);
var maxRed = Maximize(moments, first, Red, (byte)(first.RedMinimum + 1), first.RedMaximum, whole);
var maxGreen = Maximize(moments, first, Green, (byte)(first.GreenMinimum + 1), first.GreenMaximum, whole);
var maxBlue = Maximize(moments, first, Blue, (byte)(first.BlueMinimum + 1), first.BlueMaximum, whole);
if ((maxAlpha.Value >= maxRed.Value) && (maxAlpha.Value >= maxGreen.Value) && (maxAlpha.Value >= maxBlue.Value))
{
direction = Alpha;
if (!maxAlpha.Position.HasValue) return false;
}
else if ((maxRed.Value >= maxAlpha.Value) && (maxRed.Value >= maxGreen.Value) && (maxRed.Value >= maxBlue.Value))
direction = Red;
else
{
if ((maxGreen.Value >= maxAlpha.Value) && (maxGreen.Value >= maxRed.Value) && (maxGreen.Value >= maxBlue.Value))
direction = Green;
else
direction = Blue;
}
second.AlphaMaximum = first.AlphaMaximum;
second.RedMaximum = first.RedMaximum;
second.GreenMaximum = first.GreenMaximum;
second.BlueMaximum = first.BlueMaximum;
switch (direction)
{
case Alpha:
second.AlphaMinimum = first.AlphaMaximum = maxAlpha.Position.Value;
second.RedMinimum = first.RedMinimum;
second.GreenMinimum = first.GreenMinimum;
second.BlueMinimum = first.BlueMinimum;
break;
case Red:
second.RedMinimum = first.RedMaximum = maxRed.Position.Value;
second.AlphaMinimum = first.AlphaMinimum;
second.GreenMinimum = first.GreenMinimum;
second.BlueMinimum = first.BlueMinimum;
break;
case Green:
second.GreenMinimum = first.GreenMaximum = maxGreen.Position.Value;
second.AlphaMinimum = first.AlphaMinimum;
second.RedMinimum = first.RedMinimum;
second.BlueMinimum = first.BlueMinimum;
break;
case Blue:
second.BlueMinimum = first.BlueMaximum = maxBlue.Position.Value;
second.AlphaMinimum = first.AlphaMinimum;
second.RedMinimum = first.RedMinimum;
second.GreenMinimum = first.GreenMinimum;
break;
}
first.Size = (first.AlphaMaximum - first.AlphaMinimum) * (first.RedMaximum - first.RedMinimum) * (first.GreenMaximum - first.GreenMinimum) * (first.BlueMaximum - first.BlueMinimum);
second.Size = (second.AlphaMaximum - second.AlphaMinimum) * (second.RedMaximum - second.RedMinimum) * (second.GreenMaximum - second.GreenMinimum) * (second.BlueMaximum - second.BlueMinimum);
return true;
}
private static float CalculateVariance(ColorMoment[, , ,] moments, Box cube)
{
ColorMoment volume = Volume(cube, moments);
return volume.Variance();
}
private static void CalculateMoments(ColorMoment[, , ,] moments)
{
var xarea = new ColorMoment[SideSize, SideSize];
var area = new ColorMoment[SideSize];
for (var alphaIndex = 1; alphaIndex < SideSize; alphaIndex++)
{
for (var redIndex = 1; redIndex < SideSize; redIndex++)
{
Array.Clear(area, 0, area.Length);
for (var greenIndex = 1; greenIndex < SideSize; greenIndex++)
{
ColorMoment line = new ColorMoment();
for (var blueIndex = 1; blueIndex < SideSize; blueIndex++)
{
line.AddFast(ref moments[alphaIndex, redIndex, greenIndex, blueIndex]);
area[blueIndex].AddFast(ref line);
xarea[greenIndex, blueIndex].AddFast(ref area[blueIndex]);
ColorMoment moment = moments[alphaIndex - 1, redIndex, greenIndex, blueIndex];
moment.AddFast(ref xarea[greenIndex, blueIndex]);
moments[alphaIndex, redIndex, greenIndex, blueIndex] = moment;
}
}
}
}
}
private static Pixel[] BuildLookups(Box[] cubes, ColorMoment[, , ,] moments)
{
Pixel[] lookups = new Pixel[cubes.Length];
for (int cubeIndex = 0; cubeIndex < cubes.Length; cubeIndex++)
{
var volume = Volume(cubes[cubeIndex], moments);
if (volume.Weight <= 0) continue;
var lookup = new Pixel
{
Alpha = (byte)(volume.Alpha / volume.Weight),
Red = (byte)(volume.Red / volume.Weight),
Green = (byte)(volume.Green / volume.Weight),
Blue = (byte)(volume.Blue / volume.Weight)
};
lookups[cubeIndex] = lookup;
}
return lookups;
}
private static ColorMoment[, , ,] BuildHistogram(ImageBuffer sourceImage, int alphaThreshold, int alphaFader)
{
var moments = new ColorMoment[SideSize, SideSize, SideSize, SideSize];
foreach(var pixelLine in sourceImage.PixelLines)
{
for (int pixelIndex = 0; pixelIndex < pixelLine.Length; pixelIndex++)
{
Pixel pixel = pixelLine[pixelIndex];
byte pixelAlpha = pixel.Alpha;
if (pixelAlpha > alphaThreshold)
{
if (pixelAlpha < 255)
{
var alpha = pixel.Alpha + (pixel.Alpha % alphaFader);
pixelAlpha = (byte)(alpha > 255 ? 255 : alpha);
}
byte pixelRed = pixel.Red;
byte pixelGreen = pixel.Green;
byte pixelBlue = pixel.Blue;
pixelAlpha = (byte)((pixelAlpha >> SidePixShift) + 1);
pixelRed = (byte)((pixelRed >> SidePixShift) + 1);
pixelGreen = (byte)((pixelGreen >> SidePixShift) + 1);
pixelBlue = (byte)((pixelBlue >> SidePixShift) + 1);
moments[pixelAlpha, pixelRed, pixelGreen, pixelBlue].Add(pixel);
}
}
}
return moments;
}