public static Bitmap EdgeDetectConvolution(Bitmap b, EdgeDetectionMethod nType, byte nThreshold)
{
ConvMatrix m = new ConvMatrix();
// First we need to keep a copy of the original Bitmap.
using (Bitmap bTemp = (Bitmap)b.Clone())
{
try
{
switch (nType)
{
case EdgeDetectionMethod.Sobel:
m.SetAll(0);
m.TopLeft = m.BottomLeft = 1;
m.TopRight = m.BottomRight = -1;
m.MidLeft = 2;
m.MidRight = -2;
m.Offset = 0;
break;
case EdgeDetectionMethod.Prewitt:
m.SetAll(0);
m.TopLeft = m.MidLeft = m.BottomLeft = -1;
m.TopRight = m.MidRight = m.BottomRight = 1;
m.Offset = 0;
break;
case EdgeDetectionMethod.Kirsh:
m.SetAll(-3);
m.Pixel = 0;
m.TopLeft = m.MidLeft = m.BottomLeft = 5;
m.Offset = 0;
break;
}
BitmapFilter.Conv3x3(b, m);
switch (nType)
{
case EdgeDetectionMethod.Sobel:
m.SetAll(0);
m.TopLeft = m.TopRight = 1;
m.BottomLeft = m.BottomRight = -1;
m.TopMid = 2;
m.BottomMid = -2;
m.Offset = 0;
break;
case EdgeDetectionMethod.Prewitt:
m.SetAll(0);
m.BottomLeft = m.BottomMid = m.BottomRight = -1;
m.TopLeft = m.TopMid = m.TopRight = 1;
m.Offset = 0;
break;
case EdgeDetectionMethod.Kirsh:
m.SetAll(-3);
m.Pixel = 0;
m.BottomLeft = m.BottomMid = m.BottomRight = 5;
m.Offset = 0;
break;
}
BitmapFilter.Conv3x3(bTemp, m);
}
catch
{ throw; }
// GDI+ lies - return format is BGR, not RGB.
BitmapData bmpData = b.LockBits(new Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
BitmapData bmpData2 = bTemp.LockBits(new Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
try
{
int stride = bmpData.Stride;
unsafe
{
byte *p = (byte *)(void *)bmpData.Scan0;
byte *p2 = (byte *)(void *)bmpData2.Scan0;
int nOffset = stride - b.Width * 3;
int nWidth = b.Width * 3;
int nPixel = 0;
for (int y = 0; y < b.Height; ++y)
{
for (int x = 0; x < nWidth; ++x)
{
nPixel = (int)System.Math.Sqrt((p[0] * p[0]) + (p2[0] * p2[0]));
if (nPixel < nThreshold)
{
nPixel = nThreshold;
}
if (nPixel > 255)
{
nPixel = 255;
}
p[0] = (byte)nPixel;
++p;
++p2;
}
p += nOffset;
p2 += nOffset;
}
}
}
catch
{ throw; }
finally
{
b.UnlockBits(bmpData);
bTemp.UnlockBits(bmpData2);
}
}
return(b);
}
public static Bitmap EdgeDetectConvolution(Bitmap b, EdgeDetectionMethod nType, byte nThreshold)
{
ConvMatrix m = new ConvMatrix();
// First we need to keep a copy of the original Bitmap.
using (Bitmap bTemp = (Bitmap)b.Clone())
{
try
{
switch (nType)
{
case EdgeDetectionMethod.Sobel:
m.SetAll(0);
m.TopLeft = m.BottomLeft = 1;
m.TopRight = m.BottomRight = -1;
m.MidLeft = 2;
m.MidRight = -2;
m.Offset = 0;
break;
case EdgeDetectionMethod.Prewitt:
m.SetAll(0);
m.TopLeft = m.MidLeft = m.BottomLeft = -1;
m.TopRight = m.MidRight = m.BottomRight = 1;
m.Offset = 0;
break;
case EdgeDetectionMethod.Kirsh:
m.SetAll(-3);
m.Pixel = 0;
m.TopLeft = m.MidLeft = m.BottomLeft = 5;
m.Offset = 0;
break;
}
BitmapFilter.Conv3x3(b, m);
switch (nType)
{
case EdgeDetectionMethod.Sobel:
m.SetAll(0);
m.TopLeft = m.TopRight = 1;
m.BottomLeft = m.BottomRight = -1;
m.TopMid = 2;
m.BottomMid = -2;
m.Offset = 0;
break;
case EdgeDetectionMethod.Prewitt:
m.SetAll(0);
m.BottomLeft = m.BottomMid = m.BottomRight = -1;
m.TopLeft = m.TopMid = m.TopRight = 1;
m.Offset = 0;
break;
case EdgeDetectionMethod.Kirsh:
m.SetAll(-3);
m.Pixel = 0;
m.BottomLeft = m.BottomMid = m.BottomRight = 5;
m.Offset = 0;
break;
}
BitmapFilter.Conv3x3(bTemp, m);
}
catch
{ throw; }
// GDI+ lies - return format is BGR, not RGB.
BitmapData bmpData = b.LockBits(new Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
BitmapData bmpData2 = bTemp.LockBits(new Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
try
{
int stride = bmpData.Stride;
unsafe
{
byte* p = (byte*)(void*)bmpData.Scan0;
byte* p2 = (byte*)(void*)bmpData2.Scan0;
int nOffset = stride - b.Width * 3;
int nWidth = b.Width * 3;
int nPixel = 0;
for (int y = 0; y < b.Height; ++y)
{
for (int x = 0; x < nWidth; ++x)
{
nPixel = (int)System.Math.Sqrt((p[0] * p[0]) + (p2[0] * p2[0]));
if (nPixel < nThreshold) nPixel = nThreshold;
if (nPixel > 255) nPixel = 255;
p[0] = (byte)nPixel;
++p;
++p2;
}
p += nOffset;
p2 += nOffset;
}
}
}
catch
{ throw; }
finally
{
b.UnlockBits(bmpData);
bTemp.UnlockBits(bmpData2);
}
}
return b;
}
