public static Bitmap ReduceColors(Bitmap image, int numberOfColors)
{
Bitmap _return = new Bitmap(image.Width, image.Height);
MyColorComparer comparer = new MyColorComparer();
Dictionary <MyColor, int> dict = new Dictionary <MyColor, int>(comparer);
for (int i = 0; i < image.Width; ++i)
{
for (int j = 0; j < image.Height; ++j)
{
MyColor color = new MyColor(image.GetPixel(i, j));
if (dict.ContainsKey(color))
{
dict[color]++;
}
else
{
dict[color] = 0;
}
}
}
List <KeyValuePair <MyColor, int> > dictList = dict.ToList();
dictList.Sort((a, b) => b.Value - a.Value);
dict = dictList.GetRange(0, numberOfColors <= dictList.Count ? numberOfColors : dictList.Count).ToDictionary(x => x.Key, x => x.Value, comparer);
for (int i = 0; i < image.Width; ++i)
{
for (int j = 0; j < image.Height; ++j)
{
int minDist = int.MaxValue;
MyColor color = new MyColor(0, 0, 0);
MyColor currentColor = new MyColor(image.GetPixel(i, j));
foreach (var elem in dict)
{
int dist = elem.Key.Distance(currentColor);
if (dist < minDist)
{
minDist = dist;
color = elem.Key;
}
}
_return.SetPixel(i, j, color.ToColor());
}
}
return(_return);
}
public static Bitmap ReduceColors(Bitmap image, FilterMatrix filterMatrix, int numberOfColors, bool blackAndWhite)
{
double[,] filter = new double[1, 1];
switch (filterMatrix)
{
case FilterMatrix.FloydAndSteinberg:
filter = new double[3, 3];
for (int i = 0; i < 3; ++i)
{
for (int j = 0; j < 3; ++j)
{
filter[i, j] = 0;
}
}
filter[2, 1] = 7.0 / 16;
filter[0, 2] = 3.0 / 16;
filter[1, 2] = 5.0 / 16;
filter[2, 2] = 1.0 / 16;
break;
case FilterMatrix.Burkes:
filter = new double[5, 3];
for (int i = 0; i < 5; ++i)
{
for (int j = 0; j < 3; ++j)
{
filter[i, j] = 0;
}
}
filter[3, 1] = 8.0 / 32;
filter[4, 1] = 4.0 / 32;
filter[0, 2] = 2.0 / 32;
filter[1, 2] = 4.0 / 32;
filter[2, 2] = 8.0 / 32;
filter[3, 2] = 4.0 / 32;
filter[4, 2] = 2.0 / 32;
break;
case FilterMatrix.Stucky:
filter = new double[5, 5];
for (int i = 0; i < 5; ++i)
{
for (int j = 0; j < 5; ++j)
{
filter[i, j] = 0;
}
}
filter[3, 2] = 8.0 / 42;
filter[4, 2] = 4.0 / 42;
filter[0, 3] = 2.0 / 42;
filter[1, 3] = 4.0 / 42;
filter[2, 3] = 8.0 / 42;
filter[3, 3] = 4.0 / 42;
filter[4, 3] = 2.0 / 42;
filter[0, 4] = 1.0 / 42;
filter[1, 4] = 2.0 / 42;
filter[2, 4] = 4.0 / 42;
filter[3, 4] = 2.0 / 42;
filter[4, 4] = 1.0 / 42;
break;
default:
break;
}
Bitmap _return = new Bitmap(image.Width, image.Height);
MyColor[,] table = new MyColor[image.Width, image.Height];
for (int x = 0; x < image.Width; ++x)
{
for (int y = 0; y < image.Height; ++y)
{
table[x, y] = new MyColor(image.GetPixel(x, y));
}
}
int diffX = filter.GetLength(0) / 2;
int diffY = filter.GetLength(1) / 2;
for (int y = 0; y < image.Height; ++y)
{
for (int x = 0; x < image.Width; ++x)
{
MyColor oldPixel = table[x, y];
MyColor K = Approximate(table[x, y].ToColor(), numberOfColors, blackAndWhite);
table[x, y] = K;
MyColor error = oldPixel - table[x, y];
for (int i = 0; i < filter.GetLength(0); ++i)
{
for (int j = 0; j < filter.GetLength(1); ++j)
{
if (x + i - diffX >= 0 && y + j - diffY >= 0 && x + i - diffX < table.GetLength(0) && y + j - diffY < table.GetLength(1))
{
table[x + i - diffX, y + j - diffY] = table[x + i - diffX, y + j - diffY] + (error * filter[i, j]);
}
}
}
}
}
for (int x = 0; x < image.Width; ++x)
{
for (int y = 0; y < image.Height; ++y)
{
_return.SetPixel(x, y, table[x, y].ToColor());
}
}
return(_return);
}
public static Bitmap ReduceColors(Bitmap image, int numberOfColors)
{
Bitmap _return = new Bitmap(image.Width, image.Height);
List <MyColor>[] centroids1 = new List <MyColor> [numberOfColors];
List <MyColor>[] centroids2 = new List <MyColor> [numberOfColors];
for (int i = 0; i < numberOfColors; ++i)
{
centroids1[i] = new List <MyColor>();
centroids2[i] = new List <MyColor>();
centroids1[i].Add(new MyColor(rand.Next(256), rand.Next(256), rand.Next(256), rand.Next(256)));
}
List <MyColor>[] centroids = centroids1;
List <MyColor>[] last = centroids2;
bool flag = true;
while (flag)
{
for (int x = 0; x < image.Width; ++x)
{
for (int y = 0; y < image.Height; ++y)
{
int minDist = int.MaxValue;
int ind = -1;
MyColor pixelColor = new MyColor(image.GetPixel(x, y));
for (int i = 0; i < numberOfColors; ++i)
{
int dist = pixelColor.Distance(centroids[i].First());
if (dist < minDist)
{
minDist = dist;
ind = i;
}
}
centroids[ind].Add(pixelColor);
}
}
if (last[0].Count == 0)
{
last = centroids1;
centroids = centroids2;
}
else
{
flag = false;
for (int i = 0; i < numberOfColors; ++i)
{
if (centroids[i].Count != last[i].Count)
{
flag = true;
break;
}
for (int j = 1; j < centroids[i].Count; ++j)
{
if (centroids[i][j] != last[i][j])
{
flag = true;
break;
}
}
if (flag)
{
break;
}
}
if (flag)
{
if (centroids == centroids1)
{
centroids2 = new List <MyColor> [numberOfColors];
centroids = centroids2;
last = centroids1;
}
else
{
centroids1 = new List <MyColor> [numberOfColors];
centroids = centroids1;
last = centroids2;
}
}
}
if (flag)
{
for (int i = 0; i < numberOfColors; ++i)
{
MyColor avg = new MyColor(0, 0, 0, 0);
for (int j = 1; j < last[i].Count; ++j)
{
avg = avg + last[i][j];
}
avg = avg / (last[i].Count < 2 ? 1 : last[i].Count - 1);
centroids[i] = new List <MyColor>();
centroids[i].Add(avg);
}
}
}
for (int x = 0; x < image.Width; ++x)
{
for (int y = 0; y < image.Height; ++y)
{
int minDist = int.MaxValue;
int ind = -1;
MyColor pixelColor = new MyColor(image.GetPixel(x, y));
for (int i = 0; i < numberOfColors; ++i)
{
int dist = pixelColor.Distance(centroids[i].First());
if (dist < minDist)
{
minDist = dist;
ind = i;
}
}
_return.SetPixel(x, y, centroids[ind].First().ToColor());
}
}
return(_return);
}
public int Distance(MyColor color)
{
return(((int)A - (int)color.A) * ((int)A - (int)color.A) + ((int)R - (int)color.R) * ((int)R - (int)color.R) + ((int)G - (int)color.G) * ((int)G - (int)color.G) + ((int)B - (int)color.B) * ((int)B - (int)color.B));
}