/// <summary>
/// see: http://www.songho.ca/dsp/luminance/luminance.html
/// </summary>
public unsafe static void ConvertBgrToGray_Byte(IImage src, IImage dest)
{
Bgr8 *srcPtr = (Bgr8 *)src.ImageData;
byte *dstPtr = (byte *)dest.ImageData;
int width = src.Width;
int height = src.Height;
int srcShift = src.Stride - width * sizeof(Bgr8); //DO NOT divide with sizeof(Bgr8) as reminder may not be 0!!!
int dstShift = dest.Stride - width * sizeof(byte);
for (int row = 0; row < height; row++)
{
for (int col = 0; col < width; col++)
{
Bgr8.ConvertBgrToGray(srcPtr, dstPtr);
srcPtr++;
dstPtr++;
}
srcPtr = (Bgr8 *)((byte *)srcPtr + srcShift);
dstPtr = (byte *)((byte *)dstPtr + dstShift);
}
}
/// <summary>
/// Evaluates the function using the provided image.
/// </summary>
/// <param name="image">Color image.</param>
/// <returns>Entropy value. Smaller entropy is preferred.</returns>
public unsafe float Evaluate(Bgr <byte>[,] image)
{
var histogram = new int[HISTOGRAM_SIZE];
using (var uImg = image.Lock())
{
Bgr8 *imData = (Bgr8 *)uImg.ImageData;
for (int r = 0; r < uImg.Height; r++)
{
for (int c = 0; c < uImg.Width; c++)
{
Bgr8 bgr = imData[c];
float intensity = 0.2126f * bgr.R + 0.7152f * bgr.G + 0.0722f * bgr.B;
float gain = getGainAt(this, c, r, uImg.Width, uImg.Height);
int correction = (int)(gain * intensity);
updateHistogram(histogram, correction);
}
imData = (Bgr8 *)((byte *)imData + uImg.Stride);
}
}
float entropy = calculateEntropy(histogram);
return(entropy);
}
