/// <summary>
/// Computes the pixel variances and their average
/// </summary>
public override void OnEndIteration(int curIteration)
{
// Update the mean and moment based on the buffered image of the current iteration
Parallel.For(0, momentImage.Height, row => {
for (int col = 0; col < momentImage.Width; ++col)
{
float val = bufferImage.GetPixel(col, row);
momentImage.AtomicAdd(col, row, val * val / curIteration);
meanImage.AtomicAdd(col, row, val / curIteration);
}
});
// Blur both buffers to get a more stable estimate.
// TODO this could be done in-place by directly splatting in multiple pixels above
BoxFilter filter = new(1);
MonochromeImage blurredMean = new(meanImage.Width, meanImage.Height);
MonochromeImage blurredMoment = new(meanImage.Width, meanImage.Height);
filter.Apply(meanImage, blurredMean);
filter.Apply(momentImage, blurredMoment);
// Compute the final variance and update the main image
Average = 0;
Parallel.For(0, momentImage.Height, row => {
for (int col = 0; col < momentImage.Width; ++col)
{
float mean = blurredMean.GetPixel(col, row);
float variance = blurredMoment.GetPixel(col, row) - mean * mean;
variance /= (mean * mean + 0.001f);
Image.SetPixelChannel(col, row, 0, variance);
Atomic.AddFloat(ref Average, variance);
}
});
Average /= momentImage.Height * momentImage.Width;
}
