|
protected BuildObjectsMap ( |
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| image | Unmanaged image to process. | |
| return | void | |
protected override void BuildObjectsMap(UnmanagedImage image)
{
int stride = image.Stride;
// check pixel format
if ((image.PixelFormat != PixelFormat.Format8bppIndexed) &&
(image.PixelFormat != PixelFormat.Format24bppRgb) &&
(image.PixelFormat != PixelFormat.Format32bppRgb) &&
(image.PixelFormat != PixelFormat.Format32bppArgb) &&
(image.PixelFormat != PixelFormat.Format32bppPArgb))
{
throw new UnsupportedImageFormatException("Unsupported pixel format of the source image.");
}
// we don't want one pixel width images
if (ImageWidth == 1)
throw new InvalidImagePropertiesException("BlobCounter cannot process images that are one pixel wide. Rotate the image or use RecursiveBlobCounter.");
int imageWidthM1 = ImageWidth - 1;
// allocate labels array
ObjectLabels = new int[ImageWidth * ImageHeight];
// initial labels count
int labelsCount = 0;
// create map
int maxObjects = ((ImageWidth / 2) + 1) * ((ImageHeight / 2) + 1) + 1;
int[] map = new int[maxObjects];
// initially map all labels to themself
for (int i = 0; i < maxObjects; i++)
map[i] = i;
// do the job
unsafe
{
byte* src = (byte*)image.ImageData.ToPointer();
int p = 0;
if (image.PixelFormat == PixelFormat.Format8bppIndexed)
{
int offset = stride - ImageWidth;
// 1 - for pixels of the first row
if (*src > backgroundThresholdG)
ObjectLabels[p] = ++labelsCount;
++src;
++p;
// process the rest of the first row
for (int x = 1; x < ImageWidth; x++, src++, p++)
{
// check if we need to label current pixel
if (*src > backgroundThresholdG)
{
// check if the previous pixel already was labeled
if (src[-1] > backgroundThresholdG)
{
// label current pixel, as the previous
ObjectLabels[p] = ObjectLabels[p - 1];
}
else
{
// create new label
ObjectLabels[p] = ++labelsCount;
}
}
}
src += offset;
// 2 - for other rows
// for each row
for (int y = 1; y < ImageHeight; y++)
{
// for the first pixel of the row, we need to check
// only upper and upper-right pixels
if (*src > backgroundThresholdG)
{
// check surrounding pixels
if (src[-stride] > backgroundThresholdG)
{
// label current pixel, as the above
ObjectLabels[p] = ObjectLabels[p - ImageWidth];
}
else if (src[1 - stride] > backgroundThresholdG)
{
// label current pixel, as the above right
ObjectLabels[p] = ObjectLabels[p + 1 - ImageWidth];
}
else
{
// create new label
ObjectLabels[p] = ++labelsCount;
}
}
++src;
++p;
// check left pixel and three upper pixels for the rest of pixels
for (int x = 1; x < imageWidthM1; x++, src++, p++)
{
if (*src > backgroundThresholdG)
{
// check surrounding pixels
if (src[-1] > backgroundThresholdG)
{
// label current pixel, as the left
ObjectLabels[p] = ObjectLabels[p - 1];
}
else if (src[-1 - stride] > backgroundThresholdG)
{
// label current pixel, as the above left
ObjectLabels[p] = ObjectLabels[p - 1 - ImageWidth];
}
else if (src[-stride] > backgroundThresholdG)
{
// label current pixel, as the above
ObjectLabels[p] = ObjectLabels[p - ImageWidth];
}
if (src[1 - stride] > backgroundThresholdG)
{
if (ObjectLabels[p] == 0)
{
// label current pixel, as the above right
ObjectLabels[p] = ObjectLabels[p + 1 - ImageWidth];
}
else
{
int l1 = ObjectLabels[p];
int l2 = ObjectLabels[p + 1 - ImageWidth];
if ((l1 != l2) && (map[l1] != map[l2]))
{
// merge
if (map[l1] == l1)
{
// map left value to the right
map[l1] = map[l2];
}
else if (map[l2] == l2)
{
// map right value to the left
map[l2] = map[l1];
}
else
{
// both values already mapped
map[map[l1]] = map[l2];
map[l1] = map[l2];
}
// reindex
for (int i = 1; i <= labelsCount; i++)
{
if (map[i] != i)
{
// reindex
int j = map[i];
while (j != map[j])
{
j = map[j];
}
map[i] = j;
}
}
}
}
}
// label the object if it is not yet
if (ObjectLabels[p] == 0)
{
// create new label
ObjectLabels[p] = ++labelsCount;
}
}
}
// for the last pixel of the row, we need to check
// only upper and upper-left pixels
if (*src > backgroundThresholdG)
{
// check surrounding pixels
if (src[-1] > backgroundThresholdG)
{
// label current pixel, as the left
ObjectLabels[p] = ObjectLabels[p - 1];
}
else if (src[-1 - stride] > backgroundThresholdG)
{
// label current pixel, as the above left
ObjectLabels[p] = ObjectLabels[p - 1 - ImageWidth];
}
else if (src[-stride] > backgroundThresholdG)
{
// label current pixel, as the above
ObjectLabels[p] = ObjectLabels[p - ImageWidth];
}
else
{
// create new label
ObjectLabels[p] = ++labelsCount;
}
}
++src;
++p;
src += offset;
}
}
else
{
// color images
int pixelSize = Bitmap.GetPixelFormatSize(image.PixelFormat) / 8;
int offset = stride - ImageWidth * pixelSize;
int strideM1 = stride - pixelSize;
int strideP1 = stride + pixelSize;
// 1 - for pixels of the first row
if ((src[RGB.R] | src[RGB.G] | src[RGB.B]) != 0)
ObjectLabels[p] = ++labelsCount;
src += pixelSize;
++p;
// process the rest of the first row
for (int x = 1; x < ImageWidth; x++, src += pixelSize, p++)
{
// check if we need to label current pixel
if ((src[RGB.R] > backgroundThresholdR) ||
(src[RGB.G] > backgroundThresholdG) ||
(src[RGB.B] > backgroundThresholdB))
{
// check if the previous pixel already was labeled
if ((src[RGB.R - pixelSize] > backgroundThresholdR) ||
(src[RGB.G - pixelSize] > backgroundThresholdG) ||
(src[RGB.B - pixelSize] > backgroundThresholdB))
{
// label current pixel, as the previous
ObjectLabels[p] = ObjectLabels[p - 1];
}
else
{
// create new label
ObjectLabels[p] = ++labelsCount;
}
}
}
src += offset;
// 2 - for other rows
// for each row
for (int y = 1; y < ImageHeight; y++)
{
// for the first pixel of the row, we need to check
// only upper and upper-right pixels
if ((src[RGB.R] > backgroundThresholdR) ||
(src[RGB.G] > backgroundThresholdG) ||
(src[RGB.B] > backgroundThresholdB))
{
// check surrounding pixels
if ((src[RGB.R - stride] > backgroundThresholdR) ||
(src[RGB.G - stride] > backgroundThresholdG) ||
(src[RGB.B - stride] > backgroundThresholdB))
{
// label current pixel, as the above
ObjectLabels[p] = ObjectLabels[p - ImageWidth];
}
else if ((src[RGB.R - strideM1] > backgroundThresholdR) ||
(src[RGB.G - strideM1] > backgroundThresholdG) ||
(src[RGB.B - strideM1] > backgroundThresholdB))
{
// label current pixel, as the above right
ObjectLabels[p] = ObjectLabels[p + 1 - ImageWidth];
}
else
{
// create new label
ObjectLabels[p] = ++labelsCount;
}
}
src += pixelSize;
++p;
// check left pixel and three upper pixels for the rest of pixels
for (int x = 1; x < ImageWidth - 1; x++, src += pixelSize, p++)
{
if ((src[RGB.R] > backgroundThresholdR) ||
(src[RGB.G] > backgroundThresholdG) ||
(src[RGB.B] > backgroundThresholdB))
{
// check surrounding pixels
if ((src[RGB.R - pixelSize] > backgroundThresholdR) ||
(src[RGB.G - pixelSize] > backgroundThresholdG) ||
(src[RGB.B - pixelSize] > backgroundThresholdB))
{
// label current pixel, as the left
ObjectLabels[p] = ObjectLabels[p - 1];
}
else if ((src[RGB.R - strideP1] > backgroundThresholdR) ||
(src[RGB.G - strideP1] > backgroundThresholdG) ||
(src[RGB.B - strideP1] > backgroundThresholdB))
{
// label current pixel, as the above left
ObjectLabels[p] = ObjectLabels[p - 1 - ImageWidth];
}
else if ((src[RGB.R - stride] > backgroundThresholdR) ||
(src[RGB.G - stride] > backgroundThresholdG) ||
(src[RGB.B - stride] > backgroundThresholdB))
{
// label current pixel, as the above
ObjectLabels[p] = ObjectLabels[p - ImageWidth];
}
if ((src[RGB.R - strideM1] > backgroundThresholdR) ||
(src[RGB.G - strideM1] > backgroundThresholdG) ||
(src[RGB.B - strideM1] > backgroundThresholdB))
{
if (ObjectLabels[p] == 0)
{
// label current pixel, as the above right
ObjectLabels[p] = ObjectLabels[p + 1 - ImageWidth];
}
else
{
int l1 = ObjectLabels[p];
int l2 = ObjectLabels[p + 1 - ImageWidth];
if ((l1 != l2) && (map[l1] != map[l2]))
{
// merge
if (map[l1] == l1)
{
// map left value to the right
map[l1] = map[l2];
}
else if (map[l2] == l2)
{
// map right value to the left
map[l2] = map[l1];
}
else
{
// both values already mapped
map[map[l1]] = map[l2];
map[l1] = map[l2];
}
// reindex
for (int i = 1; i <= labelsCount; i++)
{
if (map[i] != i)
{
// reindex
int j = map[i];
while (j != map[j])
{
j = map[j];
}
map[i] = j;
}
}
}
}
}
// label the object if it is not yet
if (ObjectLabels[p] == 0)
{
// create new label
ObjectLabels[p] = ++labelsCount;
}
}
}
// for the last pixel of the row, we need to check
// only upper and upper-left pixels
if ((src[RGB.R] > backgroundThresholdR) ||
(src[RGB.G] > backgroundThresholdG) ||
(src[RGB.B] > backgroundThresholdB))
{
// check surrounding pixels
if ((src[RGB.R - pixelSize] > backgroundThresholdR) ||
(src[RGB.G - pixelSize] > backgroundThresholdG) ||
(src[RGB.B - pixelSize] > backgroundThresholdB))
{
// label current pixel, as the left
ObjectLabels[p] = ObjectLabels[p - 1];
}
else if ((src[RGB.R - strideP1] > backgroundThresholdR) ||
(src[RGB.G - strideP1] > backgroundThresholdG) ||
(src[RGB.B - strideP1] > backgroundThresholdB))
{
// label current pixel, as the above left
ObjectLabels[p] = ObjectLabels[p - 1 - ImageWidth];
}
else if ((src[RGB.R - stride] > backgroundThresholdR) ||
(src[RGB.G - stride] > backgroundThresholdG) ||
(src[RGB.B - stride] > backgroundThresholdB))
{
// label current pixel, as the above
ObjectLabels[p] = ObjectLabels[p - ImageWidth];
}
else
{
// create new label
ObjectLabels[p] = ++labelsCount;
}
}
src += pixelSize;
++p;
src += offset;
}
}
}
// allocate remapping array
int[] reMap = new int[map.Length];
// count objects and prepare remapping array
ObjectsCount = 0;
for (int i = 1; i <= labelsCount; i++)
{
if (map[i] == i)
{
// increase objects count
reMap[i] = ++ObjectsCount;
}
}
// second pass to complete remapping
for (int i = 1; i <= labelsCount; i++)
{
if (map[i] != i)
reMap[i] = reMap[map[i]];
}
// repair object labels
for (int i = 0, n = ObjectLabels.Length; i < n; i++)
{
ObjectLabels[i] = reMap[ObjectLabels[i]];
}
}
}