void calculateBlackAreas()
{
int[] histogram = new int[4 * 65536 * sizeof(int)];
//memset(histogram, 0, 4 * 65536 * sizeof(int));
int totalpixels = 0;
for (int i = 0; i < blackAreas.Count; i++)
{
BlackArea area = blackAreas[i];
/* Make sure area sizes are multiple of two,
* so we have the same amount of pixels for each CFA group */
area.size = area.size - (area.size & 1);
/* Process horizontal area */
if (!area.isVertical)
{
if (area.offset + area.size > uncroppedDim.y)
{
throw new RawDecoderException("RawImageData::calculateBlackAreas: Offset + size is larger than height of image");
}
for (int y = area.offset; y < area.offset + area.size; y++)
{
ushort[] pixel = previewData.Skip(mOffset.x + dim.x * y).ToArray();
int[] localhist = histogram.Skip((y & 1) * (65536 * 2)).ToArray();
for (int x = mOffset.x; x < dim.x + mOffset.x; x++)
{
localhist[((x & 1) << 16) + pixel[0]]++;
}
}
totalpixels += area.size * dim.x;
}
/* Process vertical area */
if (area.isVertical)
{
if (area.offset + area.size > uncroppedDim.x)
{
throw new RawDecoderException("RawImageData::calculateBlackAreas: Offset + size is larger than width of image");
}
for (int y = mOffset.y; y < dim.y + mOffset.y; y++)
{
ushort[] pixel = previewData.Skip(area.offset + dim.x * y).ToArray();
int[] localhist = histogram.Skip((y & 1) * (65536 * 2)).ToArray();
for (int x = area.offset; x < area.size + area.offset; x++)
{
localhist[((x & 1) << 16) + pixel[0]]++;
}
}
totalpixels += area.size * dim.y;
}
}
if (totalpixels == 0)
{
for (int i = 0; i < 4; i++)
{
blackLevelSeparate[i] = blackLevel;
}
return;
}
/* Calculate median value of black areas for each component */
/* Adjust the number of total pixels so it is the same as the median of each histogram */
totalpixels /= 4 * 2;
for (int i = 0; i < 4; i++)
{
int[] localhist = histogram.Skip(i * 65536).ToArray();
int acc_pixels = localhist[0];
int pixel_value = 0;
while (acc_pixels <= totalpixels && pixel_value < 65535)
{
pixel_value++;
acc_pixels += localhist[pixel_value];
}
blackLevelSeparate[i] = pixel_value;
}
/* If this is not a CFA image, we do not use separate blacklevels, use average */
if (!isCFA)
{
int total = 0;
for (int i = 0; i < 4; i++)
{
total += blackLevelSeparate[i];
}
for (int i = 0; i < 4; i++)
{
blackLevelSeparate[i] = (total + 2) >> 2;
}
}
}
internal static void CalculateBlackArea(RawImage image)
{
Debug.Assert(image.black == 0);
Debug.Assert(image.blackAreas.Count > 0);
int[] histogram = new int[4 * 65536 * sizeof(int)];
uint totalpixels = 0;
for (int i = 0; i < image.blackAreas.Count; i++)
{
BlackArea area = image.blackAreas[i];
// Make sure area sizes are multiple of two,
// so we have the same amount of pixels for each CFA group
area.Size = area.Size - (area.Size & 1);
// Process horizontal area
if (!area.IsVertical)
{
if (area.Offset + area.Size > image.fullSize.UncroppedDim.height)
{
throw new RawDecoderException("RawImageData::calculateBlackAreas: Offset + size is larger than height of image");
}
for (uint y = area.Offset; y < area.Offset + area.Size; y++)
{
ushort[] pixel = image.preview.rawView.Skip((int)(image.fullSize.offset.width + image.fullSize.dim.width * y)).ToArray();
int[] localhist = histogram.Skip((int)(y & 1) * (65536 * 2)).ToArray();
for (uint x = image.fullSize.offset.width; x < image.fullSize.dim.width + image.fullSize.offset.width; x++)
{
localhist[((x & 1) << 16) + pixel[0]]++;
}
}
totalpixels += area.Size * image.fullSize.dim.width;
}
// Process vertical area
if (area.IsVertical)
{
if (area.Offset + area.Size > image.fullSize.UncroppedDim.width)
{
throw new RawDecoderException("RawImageData::calculateBlackAreas: Offset + size is larger than width of image");
}
for (uint y = image.fullSize.offset.height; y < image.fullSize.dim.height + image.fullSize.offset.height; y++)
{
ushort[] pixel = image.preview.rawView.Skip((int)(area.Offset + image.fullSize.dim.width * y)).ToArray();
int[] localhist = histogram.Skip((int)(y & 1) * (65536 * 2)).ToArray();
for (uint x = area.Offset; x < area.Size + area.Offset; x++)
{
localhist[((x & 1) << 16) + pixel[0]]++;
}
}
totalpixels += area.Size * image.fullSize.dim.height;
}
}
int acc_pixels = histogram[0];
int pixel_value = 0;
while (acc_pixels <= totalpixels && pixel_value < 65535)
{
pixel_value++;
acc_pixels += histogram[pixel_value];
}
image.black = pixel_value;
Debug.Assert(image.black <= image.whitePoint);
}
