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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]];
}
}
}