/// <summary>
/// Transform this image to a greyscale version out-of-place
/// </summary>
/// <param name="source">The source image</param>
/// <param name="output">The image to write to</param>
/// <returns>The output writable lockbit image</returns>
public static WritableLockBitImage Transform(WritableLockBitImage source, WritableLockBitImage output)
{
if (source.Locked || output.Locked)
{
throw new ArgumentException("Lockbit image is locked.");
}
for (int y = 0; y < source.Height; y++)
{
for (int x = 0; x < source.Width; x++)
{
Color sourcePixel = source.GetPixel(x, y);
int greyColor =
(int)Math.Floor(sourcePixel.R * 0.299) +
(int)Math.Floor(sourcePixel.G * 0.587) +
(int)Math.Floor(sourcePixel.B * 0.114);
Color greyScale = Color.FromArgb(
greyColor,
greyColor,
greyColor
);
output.SetPixel(x, y, greyScale);
}
}
return(output);
}
private static void CopyPixels(WritableLockBitImage sourceImage, WritableLockBitImage destImage)
{
for (int row = 0; row < sourceImage.Height; row++)
{
for (int col = 0; col < sourceImage.Width; col++)
{
destImage.SetPixel(col, row, sourceImage.GetPixel(col, row));
}
}
}
private static int[] CoreCalculateSobelMatrix(WritableLockBitImage sourceImage, int[] firstKernel, int[] secondKernel)
{
// Go through each pixel in the source image
int[] intermediateResult = new int[sourceImage.Height * sourceImage.Width];
int[] inputBuffer = new int[3];
int width = sourceImage.Width;
for (int row = 0; row < sourceImage.Height; row++)
{
for (int col = 0; col < sourceImage.Width; col++)
{
// Set the input buffer
inputBuffer[0] = col > 0 ? sourceImage.GetPixel(col - 1, row).R : 0;
inputBuffer[1] = sourceImage.GetPixel(col, row).R;
inputBuffer[2] = col < sourceImage.Width - 1 ? sourceImage.GetPixel(col + 1, row).R : 0;
// Convolute it with the vector
intermediateResult[row * width + col] = ConvoluteOneDimensionalVector(inputBuffer, firstKernel);
}
}
// Go through each result in the intermediate result
int[] finalMatrix = new int[sourceImage.Height * sourceImage.Width];
for (int row = 0; row < sourceImage.Height; row++)
{
for (int col = 0; col < sourceImage.Width; col++)
{
// Set input buffer
inputBuffer[0] = row > 0 ? intermediateResult[((row - 1) * width) + col] : 0;
inputBuffer[1] = intermediateResult[row * width + col];
inputBuffer[2] = row < sourceImage.Height - 1 ? intermediateResult[((row + 1) * width) + col] : 0;
// Convolute it with the second vector
finalMatrix[row * width + col] = ConvoluteOneDimensionalVector(inputBuffer, secondKernel);
}
}
return(finalMatrix);
}
private static byte[] CalculateGrayScaleThumbnail(WritableLockBitImage image)
{
byte[] buffer = new byte[image.Width * image.Height];
for (int row = 0; row < image.Height; row++)
{
for (int col = 0; col < image.Width; col++)
{
buffer[row * image.Width + col] = image.GetPixel(col, row).R;
}
}
return(ByteCompressor.Compress(buffer));
}
/// <summary>
/// Quantisize a photo by ceiling or flooring each value depending one whether it's above or below the median value
/// </summary>
/// <param name="sourceImage">The source image</param>
/// <param name="outputImage">The image to write to</param>
/// <param name="maxValue">The value to quantize the maximum value to</param>
/// <returns>The output image, but returned for convenience</returns>
public static WritableLockBitImage Transform(WritableLockBitImage sourceImage, WritableLockBitImage outputImage, byte maxValue = byte.MaxValue)
{
Color medianColor = GetMedianColorValue(sourceImage);
for (int row = 0; row < sourceImage.Height; row++)
{
for (int col = 0; col < sourceImage.Width; col++)
{
// Quantisize the individual channels
Color currentColor = sourceImage.GetPixel(col, row);
byte outputRed, outputGreen, outputBlue;
if (currentColor.R < medianColor.R)
{
outputRed = 0;
}
else
{
outputRed = maxValue;
}
if (currentColor.G < medianColor.G)
{
outputGreen = 0;
}
else
{
outputGreen = maxValue;
}
if (currentColor.B < medianColor.B)
{
outputBlue = 0;
}
else
{
outputBlue = maxValue;
}
outputImage.SetPixel(col, row, Color.FromArgb(outputRed, outputGreen, outputBlue));
}
}
return(outputImage);
}
private static Color GetMedianColorValue(WritableLockBitImage sourceImage)
{
var setOfRedColorValues = new HashSet <int>();
var setOfGreenColorValues = new HashSet <int>();
var setOfBlueColorValues = new HashSet <int>();
for (int row = 0; row < sourceImage.Height; row++)
{
for (int col = 0; col < sourceImage.Width; col++)
{
Color color = sourceImage.GetPixel(col, row);
setOfRedColorValues.Add(color.R);
setOfGreenColorValues.Add(color.G);
setOfBlueColorValues.Add(color.B);
}
}
List <int> listOfRedColorValues = setOfRedColorValues.ToList();
List <int> listOfGreenColorValues = setOfRedColorValues.ToList();
List <int> listOfBlueColorValues = setOfRedColorValues.ToList();
listOfRedColorValues.Sort();
listOfGreenColorValues.Sort();
listOfBlueColorValues.Sort();
int count = listOfRedColorValues.Count;
int medianRed, medianGreen, medianBlue;
if (count % 2 == 0)
{
medianRed = (int)Math.Round((listOfRedColorValues[count / 2] + listOfRedColorValues[count / 2 - 1]) / 2.0);
medianGreen = (int)Math.Round((listOfGreenColorValues[count / 2] + listOfGreenColorValues[count / 2 - 1]) / 2.0);
medianBlue = (int)Math.Round((listOfBlueColorValues[count / 2] + listOfBlueColorValues[count / 2 - 1]) / 2.0);
}
else
{
medianRed = listOfRedColorValues[count / 2];
medianGreen = listOfGreenColorValues[count / 2];
medianBlue = listOfBlueColorValues[count / 2];
}
return(Color.FromArgb(medianRed, medianGreen, medianBlue));
}
/// <summary>
/// Calculate the DCT
/// </summary>
/// <param name="sourceImage">The source image to find the DCT of</param>
/// <returns>The DCT coefficients</returns>
public static double[,] Transform(WritableLockBitImage sourceImage)
{
if (sourceImage.Width != sourceImage.Height)
{
throw new ArgumentException("DCTs can only be calculated on square matrices");
}
byte[,] sourceMatrix = new byte[sourceImage.Height, sourceImage.Width];
for (int y = 0; y < sourceImage.Height; y++)
{
for (int x = 0; x < sourceImage.Width; x++)
{
// We only need the greyscale (luminance)
sourceMatrix[y, x] = sourceImage.GetPixel(x, y).R;
}
}
return(Calculate(sourceMatrix));
}
private static void PerformHorizontalBoxBlurAcc(WritableLockBitImage sourceImage, WritableLockBitImage outputImage, int radius)
{
double iarr = 1 / ((double)radius + radius + 1);
for (int row = 0; row < sourceImage.Height; row++)
{
Color firstPixel = sourceImage.GetPixel(0, row);
Color lastPixel = sourceImage.GetPixel(sourceImage.Width - 1, row);
int cumRedValue = (radius + 1) * firstPixel.R;
int cumGreenValue = (radius + 1) * firstPixel.G;
int cumBlueValue = (radius + 1) * firstPixel.B;
int currentLastColIndex = 0; // li
int currentRadiusColIndex = radius; // ri
for (int col = 0; col < radius; col++)
{
Color chosenPixel = sourceImage.GetPixel(col, row);
cumRedValue += chosenPixel.R;
cumGreenValue += chosenPixel.G;
cumBlueValue += chosenPixel.B;
}
for (int col = 0; col <= radius; col++)
{
Color chosenPixel = sourceImage.GetPixel(currentRadiusColIndex, row);
cumRedValue += chosenPixel.R - firstPixel.R;
cumGreenValue += chosenPixel.G - firstPixel.G;
cumBlueValue += chosenPixel.B - firstPixel.B;
currentRadiusColIndex++;
outputImage.SetPixel(
col,
row,
Color.FromArgb(
(int)Math.Round(cumRedValue * iarr),
(int)Math.Round(cumGreenValue * iarr),
(int)Math.Round(cumBlueValue * iarr)
)
);
}
for (int col = radius + 1; col < sourceImage.Width - radius; col++)
{
Color chosenRadiusPixel = sourceImage.GetPixel(currentRadiusColIndex, row);
Color chosenLastPixel = sourceImage.GetPixel(currentLastColIndex, row);
cumRedValue += chosenRadiusPixel.R - chosenLastPixel.R;
cumGreenValue += chosenRadiusPixel.G - chosenLastPixel.G;
cumBlueValue += chosenRadiusPixel.B - chosenLastPixel.B;
currentRadiusColIndex++;
currentLastColIndex++;
outputImage.SetPixel(
col,
row,
Color.FromArgb(
(int)Math.Round(cumRedValue * iarr),
(int)Math.Round(cumGreenValue * iarr),
(int)Math.Round(cumBlueValue * iarr)
)
);
}
for (int col = sourceImage.Width - radius; col < sourceImage.Width; col++)
{
Color chosenLastPixel = sourceImage.GetPixel(currentLastColIndex, row);
cumRedValue += lastPixel.R - chosenLastPixel.R;
cumGreenValue += lastPixel.G - chosenLastPixel.G;
cumBlueValue += lastPixel.B - chosenLastPixel.B;
currentLastColIndex++;
outputImage.SetPixel(
col,
row,
Color.FromArgb(
(int)Math.Round(cumRedValue * iarr),
(int)Math.Round(cumGreenValue * iarr),
(int)Math.Round(cumBlueValue * iarr)
)
);
}
}
}
private static void PerformTotalBoxBlurAcc(WritableLockBitImage sourceImage, WritableLockBitImage outputImage, int radius)
{
double iarr = 1 / ((double)radius + radius + 1);
for (int col = 0; col < sourceImage.Width; col++)
{
Color topPixel = sourceImage.GetPixel(col, 0);
Color bottomPixel = sourceImage.GetPixel(col, sourceImage.Height - 1);
int cumRedValue = (radius + 1) * topPixel.R;
int cumGreenValue = (radius + 1) * topPixel.G;
int cumBlueValue = (radius + 1) * topPixel.B;
for (int row = 0; row < radius; row++)
{
Color chosenPixel = sourceImage.GetPixel(col, row);
cumRedValue += chosenPixel.R;
cumGreenValue += chosenPixel.G;
cumBlueValue += chosenPixel.B;
}
for (int row = 0; row <= radius; row++)
{
Color chosenPixel = sourceImage.GetPixel(col, row + radius);
cumRedValue += chosenPixel.R - topPixel.R;
cumGreenValue += chosenPixel.G - topPixel.G;
cumBlueValue += chosenPixel.B - topPixel.B;
outputImage.SetPixel(
col,
row,
Color.FromArgb(
(int)Math.Round(cumRedValue * iarr),
(int)Math.Round(cumGreenValue * iarr),
(int)Math.Round(cumBlueValue * iarr)
)
);
}
for (int row = radius + 1; row < sourceImage.Height - radius; row++)
{
Color radiusPixel = sourceImage.GetPixel(col, radius + row);
Color laggingPixel = sourceImage.GetPixel(col, row - radius - 1);
cumRedValue += radiusPixel.R - laggingPixel.R;
cumGreenValue += radiusPixel.G - laggingPixel.G;
cumBlueValue += radiusPixel.B - laggingPixel.B;
outputImage.SetPixel(
col,
row,
Color.FromArgb(
(int)Math.Round(cumRedValue * iarr),
(int)Math.Round(cumGreenValue * iarr),
(int)Math.Round(cumBlueValue * iarr)
)
);
}
for (int row = sourceImage.Height - radius; row < sourceImage.Height; row++)
{
Color laggingPixel = sourceImage.GetPixel(col, row - radius);
cumRedValue += bottomPixel.R - laggingPixel.R;
cumGreenValue += bottomPixel.G - laggingPixel.G;
cumBlueValue += bottomPixel.B - laggingPixel.B;
outputImage.SetPixel(
col,
row,
Color.FromArgb(
(int)Math.Round(cumRedValue * iarr),
(int)Math.Round(cumGreenValue * iarr),
(int)Math.Round(cumBlueValue * iarr)
)
);
}
}
}