/*
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;
}
/*
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;
}
}
}
}
/*
undoes zig zag on an int array, and outputs the original 8x8 block
*/
public Block undoZigZag(int[] array) {
Block block = new Block();
int arrayPos = 0;
int yMove = -1;
int xMove = 1;
int x = 0;
int y = 0;
block.set(x, y, array[arrayPos++]);
for (int level = 0; level < 8; level++)
{
for (int depth = 0; depth < level; depth++)
{
x += xMove;
y += yMove;
block.set(x, y, array[arrayPos++]);
}
if (level == 7) break;
if (xMove < 0) y++; else x++;
block.set(x, y, array[arrayPos++]);
yMove *= -1;
xMove *= -1;
}
yMove *= -1;
xMove *= -1;
if (xMove < 0) y++; else x++;
block.set(x, y, array[arrayPos++]);
for (int level = 6; level > 0; level--)
{
for (int depth = level; depth > 0; depth--)
{
x += xMove;
y += yMove;
block.set(x, y, array[arrayPos++]);
}
if (xMove < 0) x++; else y++;
block.set(x, y, array[arrayPos++]);
yMove *= -1;
xMove *= -1;
}
return block;
}
/*
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;
}
/*
Generates an 8x8 block from a position
*/
public Block generateBlock(double[,] fullSize, int xPosition, int yPosition) {
Block block = new Block();
for (int y=yPosition; y<yPosition+8; y++) {
for (int x=xPosition; x<xPosition+8; x++) {
if (x < fullSize.GetLength(0) && y < fullSize.GetLength(1))
{
block.set(x-xPosition,y-yPosition,fullSize[x,y]);
}
else {
block.set(x - xPosition, y - yPosition, 0.0);
}
}
}
return block;
}
