private static int GetMask(WuPixel[] palette)
{
IEnumerable <byte> alphas = from pixel in palette
select pixel.Alpha;
byte maxAlpha = alphas.Max();
int uniqueAlphas = alphas.Distinct().Count();
IEnumerable <byte> reds = from pixel in palette
select pixel.Red;
byte maxRed = reds.Max();
int uniqueReds = reds.Distinct().Count();
IEnumerable <byte> greens = from pixel in palette
select pixel.Green;
byte maxGreen = greens.Max();
int uniqueGreens = greens.Distinct().Count();
IEnumerable <byte> blues = from pixel in palette
select pixel.Blue;
byte maxBlue = blues.Max();
int uniqueBlues = blues.Distinct().Count();
double totalUniques = uniqueAlphas + uniqueReds + uniqueGreens + uniqueBlues;
double AvailableBits = 1.0 + Math.Log(uniqueAlphas * uniqueReds * uniqueGreens * uniqueBlues);
byte alphaMask = ComputeBitMask(maxAlpha, Convert.ToInt32(Math.Round(uniqueAlphas / totalUniques * AvailableBits)));
byte redMask = ComputeBitMask(maxRed, Convert.ToInt32(Math.Round(uniqueReds / totalUniques * AvailableBits)));
byte greenMask = ComputeBitMask(maxGreen, Convert.ToInt32(Math.Round(uniqueGreens / totalUniques * AvailableBits)));
byte blueMask = ComputeBitMask(maxAlpha, Convert.ToInt32(Math.Round(uniqueBlues / totalUniques * AvailableBits)));
WuPixel maskedPixel = new WuPixel(alphaMask, redMask, greenMask, blueMask);
return(maskedPixel.Argb);
}
public void AddPixel(WuPixel pixel)
{
Alpha += pixel.Alpha;
Red += pixel.Red;
Green += pixel.Green;
Blue += pixel.Blue;
Sum++;
}
public void Add(WuPixel p)
{
byte pAlpha = p.Alpha;
byte pRed = p.Red;
byte pGreen = p.Green;
byte pBlue = p.Blue;
Alpha += pAlpha;
Red += pRed;
Green += pGreen;
Blue += pBlue;
Weight++;
Moment += pAlpha * pAlpha + pRed * pRed + pGreen * pGreen + pBlue * pBlue;
}
public byte GetPaletteIndex(WuPixel pixel)
{
int pixelKey = pixel.Argb & mMask;
LookupNode[] bucket;
if (!mLookup.TryGetValue(pixelKey, out bucket))
{
bucket = Palette;
}
if (bucket.Length == 1)
{
return(bucket[0].PaletteIndex);
}
int bestDistance = int.MaxValue;
byte bestMatch = 0;
foreach (var lookup in bucket)
{
var lookupPixel = lookup.Pixel;
var deltaAlpha = pixel.Alpha - lookupPixel.Alpha;
int distance = deltaAlpha * deltaAlpha;
var deltaRed = pixel.Red - lookupPixel.Red;
distance += deltaRed * deltaRed;
var deltaGreen = pixel.Green - lookupPixel.Green;
distance += deltaGreen * deltaGreen;
var deltaBlue = pixel.Blue - lookupPixel.Blue;
distance += deltaBlue * deltaBlue;
if (distance >= bestDistance)
{
continue;
}
bestDistance = distance;
bestMatch = lookup.PaletteIndex;
}
if ((bucket == Palette) && (pixelKey != 0))
{
mLookup[pixelKey] = new LookupNode[] { bucket[bestMatch] };
}
return(bestMatch);
}
private static byte[] IndexedPixels(Color[] pixels, WuPixel[] lookups, int alphaThreshold, int maxColors, PaletteColorHistory[] paletteHistogram)
{
var length = maxColors == 256 ? pixels.Length : maxColors == 16 ? pixels.Length / 2 : throw new Exception("IndexedPixels: unknown pixelformat");
byte[] returned = new byte[length];
PaletteLookup lookup = new PaletteLookup(lookups);
--maxColors;
for (int i = 0; i < pixels.Length; i++)
{
WuPixel pixel = new WuPixel(pixels[i].A, pixels[i].R, pixels[i].G, pixels[i].B);
byte bestMatch = (byte)maxColors;
if (pixel.Alpha > alphaThreshold)
{
bestMatch = lookup.GetPaletteIndex(pixel);
paletteHistogram[bestMatch].AddPixel(pixel);
}
switch (maxColors)
{
case 256 - 1:
returned[i] = bestMatch;
break;
case 16 - 1:
if (i % 2 == 0)
{
returned[i / 2] = (byte)(bestMatch << 4);
}
else
{
returned[i / 2] |= (byte)(bestMatch & 0x0F);
}
break;
case 2 - 1:
if (i % 8 == 0)
{
returned[i / 8] = (byte)(bestMatch << 7);
}
else
{
returned[i / 8] |= (byte)((bestMatch & 0x01) << (7 - (i % 8)));
}
break;
}
}
return(returned);
}
private static WuPixel[] BuildLookups(Box[] cubes, ColorMoment[,,,] moments)
{
WuPixel[] lookups = new WuPixel[cubes.Length];
for (int cubeIndex = 0; cubeIndex < cubes.Length; cubeIndex++)
{
var volume = Volume(cubes[cubeIndex], moments);
if (volume.Weight <= 0)
{
continue;
}
var lookup = new WuPixel
{
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);
}
