/*
Returns the amount of error compared to a given block at the current position
*/
public void getOriginalFromError(double[,] image, Block errorBlock, int xPos, int yPos, int channel)
{
xPos -= 4;
yPos -= 4;
double error = 0;
double pixelValue;
double currentError;
Color color = new Color();
switch (channel)
{
case 1:
YpostBlock = new Block();
break;
case 2:
CbpostBlock = new Block();
break;
case 3:
CrpostBlock = new Block();
break;
}
for (int y = yPos; y < yPos + 8; y++)
{
for (int x = xPos; x < xPos + 8; x++)
{
//if out of bounds, treat as a value of zero
if (y >= image.GetLength(1) || x >= image.GetLength(0) || x < 0 || y < 0)
{
switch (channel)
{
case 1:
YpostBlock.set(x - xPos, y - yPos, Math.Round(Math.Abs(0 + errorBlock.get(x - xPos, y - yPos))));
break;
case 2:
CbpostBlock.set(x - xPos, y - yPos, Math.Round(Math.Abs(0 + errorBlock.get(x - xPos, y - yPos))));
break;
case 3:
CrpostBlock.set(x - xPos, y - yPos, Math.Round(Math.Abs(0 + errorBlock.get(x - xPos, y - yPos))));
break;
}
continue;
}
currentError = Math.Abs(image[x, y] + errorBlock.get(x - xPos, y - yPos));
switch (channel)
{
case 1:
YerrorBlock.set(x - xPos, y - yPos, Math.Round(currentError));
break;
case 2:
CbpostBlock.set(x - xPos, y - yPos, Math.Round(currentError));
break;
case 3:
CrpostBlock.set(x - xPos, y - yPos, Math.Round(currentError));
break;
}
}
}
}
/*
Returns the amount of error compared to a given block at the current position
*/
public double getErrorForPosition(double[,] image, Block comparison, int xPos, int yPos, int channel) {
xPos -= 4;
yPos -= 4;
double error = 0;
double pixelValue;
double currentError;
Color color = new Color();
switch (channel)
{
case 1:
YerrorBlock = new Block();
break;
case 2:
CberrorBlock = new Block();
break;
case 3:
CrerrorBlock = new Block();
break;
}
for (int y=yPos; y<yPos+8; y++) {
for (int x=xPos; x<xPos+8; x++) {
//if out of bounds, treat as a value of zero
if (y >= image.GetLength(1) || x >= image.GetLength(0)||x<0||y<0) {
switch (channel)
{
case 1:
YerrorBlock.set(x - xPos, y - yPos, Math.Round(0 - comparison.get(x - xPos, y - yPos)));
break;
case 2:
CberrorBlock.set(x - xPos, y - yPos, Math.Round((0 - comparison.get(x - xPos, y - yPos))));
break;
case 3:
CrerrorBlock.set(x - xPos, y - yPos, Math.Round((0 - comparison.get(x - xPos, y - yPos))));
break;
}
error += Math.Abs(0 - comparison.get(x - xPos, y - yPos));
continue;
}
currentError = image[x,y]-comparison.get(x-xPos, y-yPos);
error += Math.Abs(currentError);
switch (channel)
{
case 1:
YerrorBlock.set(x - xPos, y - yPos, Math.Round(currentError));
break;
case 2:
CberrorBlock.set(x - xPos, y - yPos, Math.Round(currentError));
break;
case 3:
CrerrorBlock.set(x - xPos, y - yPos, Math.Round(currentError));
break;
}
}
}
if (xPos == 3 && yPos == 0)
{
//Debug.WriteLine("----------------------------ErrorBlock-----------------------------------");
for (int q = 0; q < 8; q++)
{
for (int w = 0; w < 8; w++)
{
//Debug.Write(errorBlock.get(q, w) + ",");
//Debug.Write(comparison.get(q, w) + ",");
}
// Debug.WriteLine("");
}
// Debug.WriteLine("----------------------------------------------------------------------------------------------");
}
error /= 64;
// Debug.WriteLine("Total error = "+error);
return error;
}
/*
converts a block into a 1 dimensional array
*/
public int[] applyZigZag(Block block) {
int[] zigzag = new int[64];
int arrayPos =0;
int yMove = -1;
int xMove = 1;
int x = 0;
int y = 0;
zigzag[arrayPos++] = (int)block.get(x, y);
for (int level = 0; level < 8; level++)
{
for (int depth = 0; depth < level; depth++)
{
x += xMove;
y += yMove;
zigzag[arrayPos++] = (int)block.get(x,y);
}
if (level == 7) break;
if (xMove < 0) y++; else x++;
zigzag[arrayPos++] = (int)block.get(x, y);
yMove *= -1;
xMove *= -1;
}
yMove *= -1;
xMove *= -1;
if (xMove < 0) y++; else x++;
zigzag[arrayPos++] = (int)block.get(x, y);
for (int level = 6; level > 0; level--)
{
for (int depth = level; depth > 0; depth--)
{
x += xMove;
y += yMove;
zigzag[arrayPos++] = (int)block.get(x, y);
}
if (xMove < 0) x++; else y++;
zigzag[arrayPos++] = (int)block.get(x, y);
yMove *= -1;
xMove *= -1;
}
return zigzag;
}
/*
Multiplies the values of a quantized block by a quantization table to undo quantization. returns the outcome
*/
public Block RemoveQuantization(Block block, int[,] table)
{
Block quantizedBlock = new Block();
for (int y = 0; y < 8; y++)
{
for (int x = 0; x < 8; x++)
{
quantizedBlock.set(x, y, block.get(x, y) * table[x, y]);
}
}
return quantizedBlock;
}
/*
Divides the values of the block by a passed quantization table, and returns the outcome
*/
public Block applyQuantization(Block block, int[,] table) {
Block quantizedBlock = new Block();
for (int y=0; y<8; y++) {
for (int x=0; x<8; x++) {
quantizedBlock.set(x,y,Math.Round((double)block.get(x, y) / table[x, y]));
}
}
return quantizedBlock;
}
/*
Applies inverse DCT formula and returns the image pixel
*/
public double applyIDCTFormula(Block input, double i, double j) {
double sum = 0, firstCos, secondCos;
for (double u=0; u<8; u++) {
for (double v=0; v<8; v++) {
firstCos = Math.Cos((2*i+1)*u*Math.PI/16);
secondCos = Math.Cos((2*j+1)*v*Math.PI/16);
sum += c(u) * c(v) /4 * firstCos * secondCos*input.get((int)u,(int)v);
}
}
return sum;
}
/*
Applies DCT formula to a block, and returns the post DCT pixel
*/
public double applyDCTFormula(Block input, double u, double v) {
double sum=0, firstCos, secondCos;
for (double i=0; i<8; i++) {
for (double j=0; j<8; j++) {
firstCos = Math.Cos((2*i+1)*u*Math.PI/16);
secondCos = Math.Cos((2 * j + 1) * v * Math.PI / 16);
sum += (firstCos * secondCos * input.get((int)i, (int)j));
//if (i < 4 && j < 4) sum += firstCos * secondCos * input.get((int)i, (int)j);
}
}
sum *= c(u) * c(v) / 4;
return sum;
}
