public void Add(VQBlock block)
{
for (int i = 0; i < Pixels.Length; i++)
{
Pixels[i] += block.Pixels[i];
}
}
public VQCodeBook(int codeBookSize, int blockWidth, int blockHeight)
{
Entries = new VQBlock[codeBookSize];
for (int i = 0; i < Entries.Length; i++)
{
Entries[i] = new VQBlock(blockWidth, blockHeight);
}
}
public double EuclidianDistance(ref VQBlock block)
{
double total = 0.0f;
for (int i = 0; i < Pixels.Length; i++)
{
total += System.Numerics.Vector4.DistanceSquared(Pixels[i], block.Pixels[i]);
}
return(total);
}
public double EuclidianDistance2x2(ref VQBlock block)
{
double total = 0.0;
total += System.Numerics.Vector4.DistanceSquared(Pixels[0], block.Pixels[0]);
total += System.Numerics.Vector4.DistanceSquared(Pixels[1], block.Pixels[1]);
total += System.Numerics.Vector4.DistanceSquared(Pixels[2], block.Pixels[2]);
total += System.Numerics.Vector4.DistanceSquared(Pixels[3], block.Pixels[3]);
return(total);
}
/// <summary>
/// Initializes the code book.
/// </summary>
/// <param name="imageBlocks">The blocks of the image.</param>
/// <param name="codeBookSize">Size of the code book.</param>
/// <param name="fastInitialization">True for using simple initialization. False uses improved initialization.</param>
/// <returns></returns>
private static VQBlock[] InitCodeBook(ref VQBlock[] imageBlocks, int codeBookSize, bool fastInitialization = false)
{
if (fastInitialization)
{
int i = 0;
VQBlock[] codeBook = new VQBlock[codeBookSize];
for (i = 0; i < codeBookSize; i++)
{
codeBook[i % codeBookSize] = new VQBlock(imageBlocks[i]);
}
for (i = 0; i < imageBlocks.Length; i++)
{
imageBlocks[i].Group = i % codeBookSize;
}
return(codeBook);
}
else
{
int i = 0;
int imageLength = imageBlocks.Length;
double sum = 0.0;
double[] distances = new double[imageBlocks.Length];
VQBlock[] codeBook = new VQBlock[codeBookSize];
Random rand = new Random();
codeBook[0] = new VQBlock(imageBlocks[rand.Next() % imageBlocks.Length]);
for (int cluster = 1; cluster < codeBookSize; cluster++)
{
sum = 0;
for (i = 0; i < imageLength; i++)
{
Nearest(imageBlocks[i], codeBook, cluster, ref distances[i]);
sum += distances[i];
}
sum = sum * rand.Next(0x7fff) / (0x7fff - 1.0);
for (i = 0; i < imageLength; i++)
{
if ((sum -= distances[i]) > 0)
{
continue;
}
codeBook[cluster] = new VQBlock(imageBlocks[i]);
break;
}
}
double dump = 0.0;
for (i = 0; i < imageLength; i++)
{
imageBlocks[i].Group = Nearest(imageBlocks[i], codeBook, codeBookSize, ref dump);
}
return(codeBook);
}
}
/// <summary>
/// Quantizes the bitmap with the given code book.
/// </summary>
/// <param name="bitmap">The bitmap.</param>
/// <param name="codeBook">The code book.</param>
/// <returns></returns>
public static byte[] QuantizeImage(Bitmap bitmap, VQCodeBook codeBook)
{
VQBlock[] blocks = CreateBlocks(bitmap, codeBook.BlockWidth, codeBook.BlockHeight);
byte[] result = new byte[blocks.Length];
double dump = 0.0;
for (int i = 0; i < blocks.Length; i++)
{
VQBlock block = blocks[i];
result[i] = (byte)Nearest(block, codeBook.Entries, codeBook.Entries.Length, ref dump);
}
return(result);
}
public VQBlock(VQBlock block)
{
BlockWidth = block.BlockWidth;
BlockHeight = block.BlockHeight;
Group = block.Group;
Pixels = new System.Numerics.Vector4[BlockWidth * BlockHeight];
for (int i = 0; i < Pixels.Length; i++)
{
Pixels[i].X = block.Pixels[i].X;
Pixels[i].Y = block.Pixels[i].Y;
Pixels[i].Z = block.Pixels[i].Z;
Pixels[i].W = block.Pixels[i].W;
}
}
/// <summary>
/// Creates the an block array of the given bitmap.
/// </summary>
/// <param name="bitmap">The bitmap.</param>
/// <param name="blockWidth">Width of the blocks.</param>
/// <param name="blockHeight">Height of the blocks.</param>
/// <returns></returns>
public static VQBlock[] CreateBlocks(Bitmap bitmap, int blockWidth = 2, int blockHeight = 2)
{
//Read bitmap into buffer
ConvertBitmapArgb(ref bitmap);
byte[] imageBuffer = new byte[bitmap.Width * bitmap.Height * 4];
BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadOnly, bitmap.PixelFormat);
Marshal.Copy(bitmapData.Scan0, imageBuffer, 0, imageBuffer.Length);
//Convert bitmap to blocks
int width = bitmap.Width / blockWidth;
int height = bitmap.Height / blockHeight;
int blockSize = blockWidth * blockHeight * 4;
int blockCount = width * height;
VQBlock[] blocks = new VQBlock[blockCount];
for (int y = 0; y < bitmap.Height - 1; y += blockHeight)
{
for (int x = 0; x < bitmap.Width - 1; x += blockWidth)
{
int blockIndex = (y / blockHeight) * width + (x / blockWidth);
blocks[blockIndex] = new VQBlock(blockWidth, blockHeight);
for (int k = 0; k < blockHeight; k++)
{
for (int l = 0; l < blockWidth; l++)
{
int imageIndex = ((y + k) * bitmap.Width + (x + l)) * 4;
byte b = imageBuffer[imageIndex];
byte g = imageBuffer[imageIndex + 1];
byte r = imageBuffer[imageIndex + 2];
byte a = imageBuffer[imageIndex + 3];
int subVectorIndex = k * blockWidth + l;
blocks[blockIndex].Pixels[subVectorIndex].X = b;
blocks[blockIndex].Pixels[subVectorIndex].Y = g;
blocks[blockIndex].Pixels[subVectorIndex].Z = r;
blocks[blockIndex].Pixels[subVectorIndex].W = a;
}
}
}
}
bitmap.UnlockBits(bitmapData);
return(blocks);
}
/// <summary>
/// Finds the nearest matching block of the given code book cluster
/// </summary>
/// <param name="block">The block that will be searched for.</param>
/// <param name="cluster">The code book cluster where the block will be searched in.</param>
/// <param name="clusterSize">Size of the code book cluster.</param>
/// <param name="nearestDistance">The nearest distance that was found.</param>
/// <returns>Nearest group index</returns>
private static int Nearest(VQBlock block, VQBlock[] cluster, int clusterSize, ref double nearestDistance)
{
int i = 0;
int nearestIndex = 0;
double distance = 0;
double minDistance = 0;
for (i = 0; i < clusterSize; i++)
{
minDistance = double.PositiveInfinity;
nearestIndex = block.Group;
for (i = 0; i < clusterSize; i++)
{
if (minDistance > (distance = cluster[i].EuclidianDistance(ref block)))
{
minDistance = distance;
nearestIndex = i;
}
}
}
nearestDistance = minDistance;
return(nearestIndex);
}
/// <summary>
/// Generates a code book for the given bitmap.
/// </summary>
/// <param name="bitmap">The bitmap from which the code book will be generated.</param>
/// <param name="codeBookSize">Size of the code book.</param>
/// <param name="blockWidth">Width of the code book blocks.</param>
/// <param name="blockHeight">Height of the code book blocks.</param>
/// <returns></returns>
/// <exception cref="ArgumentException">The image can't be devided by the given block size!</exception>
public static VQCodeBook CreateCodebook(Bitmap bitmap, int codeBookSize, int blockWidth = 2, int blockHeight = 2)
{
if (bitmap.Width % blockWidth != 0 || bitmap.Height % blockHeight != 0)
{
throw new ArgumentException("The image can't be devided by the given block size!");
}
//Convert image to blocks
VQBlock[] imageBlocks = CreateBlocks(bitmap, blockWidth, blockHeight);
//Create and initialize codebook
VQBlock[] codeBookBlocks = InitCodeBook(ref imageBlocks, codeBookSize);
//Create codebook (k-means/Lloyd algorithm)
int i = 0;
int j = 0;
int changed = 0;
int nearestIndex = 0;
VQBlock imageBlock = null;
VQBlock codeBookBlock = null;
double dump = 0.0;
int runs = 0;
do
{
for (i = 0; i < codeBookSize; i++)
{
codeBookBlock = codeBookBlocks[i];
codeBookBlock.Group = 0;
codeBookBlock.Zero();
}
for (j = 0; j < imageBlocks.Length; j++)
{
imageBlock = imageBlocks[j];
codeBookBlock = codeBookBlocks[imageBlock.Group];
codeBookBlock.Group += 1;
codeBookBlock.Add(imageBlock);
}
for (i = 0; i < codeBookSize; i++)
{
codeBookBlock = codeBookBlocks[i];
codeBookBlock.Div(codeBookBlock.Group);
}
changed = 0;
for (j = 0; j < imageBlocks.Length; j++)
{
imageBlock = imageBlocks[j];
nearestIndex = Nearest(imageBlock, codeBookBlocks, codeBookSize, ref dump);
if (nearestIndex != imageBlock.Group)
{
changed++;
imageBlock.Group = nearestIndex;
}
}
runs++;
} while (changed > (imageBlocks.Length >> 10));
for (i = 0; i < codeBookSize; i++)
{
codeBookBlock = codeBookBlocks[i];
codeBookBlock.Group = i;
}
return(new VQCodeBook(codeBookBlocks));
}
