/// <summary>
/// Returns the distance from the target color histogram the given pixel array is
/// </summary>
/// <param name="pixelArray">The pixel array of the bitmap to get the distance of</param>
/// <param name="bitmapWidth">The width of the bitmap</param>
/// <param name="bitmapHeight">The height of the bitmap</param>
/// <param name="stride">The number of bytes per row</param>
/// <param name="targetColor">The histogram of the color of the target object</param>
/// <returns>The minimum distance a subrect of the image is from the target histogram</returns>
private static double GetColorDistance(byte[] pixelArray, int bitmapWidth, int bitmapHeight, int stride, double[] targetColor)
{
var colorDistancePixelArray = (byte[])pixelArray.Clone();
var pixelArrayLock = new object();
// Threshold the image for possible areas where the object is
Parallel.ForEach(ExtensionMethods.SteppedRange(0, bitmapWidth, 8), column =>
{
Parallel.ForEach(ExtensionMethods.SteppedRange(0, bitmapHeight, 8), row =>
{
int width = Math.Min(8, bitmapWidth - column);
int height = Math.Min(8, bitmapHeight - row);
var croppedPixelArray = pixelArray.CropPixelArray(column, row, width, height, stride);
var colorBins = ColorClassifier.GetColorBins(croppedPixelArray, true);
var distance = ColorClassifier.CalculateBinDistance(colorBins, targetColor);
// Possible areas where the object we are looking for is are black 0
byte newColor = distance >= 125 ? (byte)255 : (byte)0;
for (int i = 0; i < width; i++)
{
for (int j = 0; j < height; j++)
{
int index = (row + j) * stride + 4 * (column + i);
lock ( pixelArrayLock )
{
colorDistancePixelArray[index] = colorDistancePixelArray[index + 1] = colorDistancePixelArray[index + 2] = newColor;
}
}
}
});
});
// Look at each blob and determine if it is our
// object with a stricted threshold
var tempBitmap = new WriteableBitmap(bitmapWidth, bitmapHeight, 96, 96, PixelFormats.Bgr32, null);
tempBitmap.WritePixels(new Int32Rect(0, 0, bitmapWidth, bitmapHeight), colorDistancePixelArray, stride, 0);
double minDistance = double.PositiveInfinity;
var allBlobDistance = GetColorBinDistance(pixelArray, colorDistancePixelArray, stride, targetColor, tempBitmap, Colors.Black);
if (allBlobDistance <= 105)
{
minDistance = allBlobDistance;
}
var blobColors = BitmapColorer.ColorBitmap(tempBitmap);
foreach (var color in blobColors)
{
var distance = GetColorBinDistance(pixelArray, colorDistancePixelArray, stride, targetColor, tempBitmap, color);
if (distance <= minDistance)
{
minDistance = distance;
}
}
return(minDistance);
}
private static double GetColorBinDistance(byte[] pixelArray, byte[] thresholdedPixelArray, int stride, double[] targetHistogram, WriteableBitmap tempBitmap, Color color)
{
var boundingBox = BitmapColorer.GetBoundingBoxOfColor(tempBitmap, color);
var croppedPixelArray = pixelArray.CropPixelArray((int)boundingBox.X, (int)boundingBox.Y, (int)boundingBox.Width, (int)boundingBox.Height, stride);
var croppedThresholdedArray = thresholdedPixelArray.CropPixelArray((int)boundingBox.X, (int)boundingBox.Y, (int)boundingBox.Width, (int)boundingBox.Height, stride);
var colorBins = ColorClassifier.GetColorBinsWithinBlob(croppedPixelArray, croppedThresholdedArray, true);
var distance = ColorClassifier.CalculateBinDistance(colorBins, targetHistogram);
return(distance);
}
