private static (List <System.Drawing.Color> colors, Dictionary <System.Drawing.Color, int> lookup) MedianCut(List <System.Drawing.Color> allColors, int stages)
{
MedianCutNode node = MedianCutInternal(allColors, stages);
List <List <Color> > bucketedColors = new List <List <Color> >();
node.GetColors(bucketedColors);
List <System.Drawing.Color> colors = new List <System.Drawing.Color>();
foreach (List <Color> cs in bucketedColors)
{
colors.Add(cs[0]); // TODO: use average instead
}
Dictionary <System.Drawing.Color, int> colorLookupTable = new Dictionary <System.Drawing.Color, int>();
for (int ci = 0; ci < bucketedColors.Count; ++ci)
{
foreach (Color c in bucketedColors[ci])
{
colorLookupTable.Add(c, ci);
}
}
return(colors, colorLookupTable);
}
private static MedianCutNode MedianCutInternal(List <System.Drawing.Color> colors, int stages)
{
if (colors.Count == 0)
{
return(new MedianCutNode());
}
int minr = colors.Min(x => x.R);
int maxr = colors.Max(x => x.R);
int ming = colors.Min(x => x.G);
int maxg = colors.Max(x => x.G);
int minb = colors.Min(x => x.B);
int maxb = colors.Max(x => x.B);
int mina = colors.Min(x => x.A);
int maxa = colors.Max(x => x.A);
int diffr = maxr - minr;
int diffg = maxg - ming;
int diffb = maxb - minb;
int diffa = maxa - mina;
int biggestDiffIdx = 3;
int biggestDiff = diffa;
int biggestDiffMin = mina;
int biggestDiffMax = maxa;
if (biggestDiff < diffg)
{
biggestDiff = diffg;
biggestDiffIdx = 1;
biggestDiffMin = ming;
biggestDiffMax = maxg;
}
if (biggestDiff < diffr)
{
biggestDiff = diffr;
biggestDiffIdx = 0;
biggestDiffMin = minr;
biggestDiffMax = maxr;
}
if (biggestDiff < diffb)
{
biggestDiff = diffb;
biggestDiffIdx = 2;
biggestDiffMin = minb;
biggestDiffMax = maxb;
}
int cutoff = (biggestDiffMin + biggestDiffMax + 1) / 2;
List <Color> left = new List <Color>();
List <Color> right = new List <Color>();
foreach (Color c in colors)
{
if (c.GetColorComponent(biggestDiffIdx) < cutoff)
{
left.Add(c);
}
else
{
right.Add(c);
}
}
MedianCutNode node = new MedianCutNode();
if (stages <= 1)
{
node.LeftColors = left;
node.RightColors = right;
}
else
{
node.LeftChild = MedianCutInternal(left, stages - 1);
node.RightChild = MedianCutInternal(right, stages - 1);
}
return(node);
}
