} // end of AutoFitThreshold
/// <summary>
/// 图像灰度变换
/// </summary>
/// <param name="b">位图流</param>
/// <param name="grayMethod">灰度方法</param>
/// <returns></returns>
public Bitmap Gray(Bitmap b, GrayMethod grayMethod)
{
int width = b.Width;
int height = b.Height;
BitmapData data = b.LockBits(new Rectangle(0, 0, width, height),
ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
unsafe
{
byte *p = (byte *)data.Scan0;
int offset = data.Stride - width * BPP;
byte R, G, B, gray;
switch (grayMethod)
{
case GrayMethod.Maximum:
for (int y = 0; y < height; y++)
{
for (int x = 0; x < width; x++)
{
R = p[2];
G = p[1];
B = p[0];
// gray = Max( R, G, B )
gray = (gray = B >= G ? B : G) >= R ? gray : R;
p[0] = p[1] = p[2] = gray;
p += BPP;
} // x
p += offset;
} // y
break;
case GrayMethod.Average:
for (int y = 0; y < height; y++)
{
for (int x = 0; x < width; x++)
{
R = p[2];
G = p[1];
B = p[0];
// gray = ( R + G + B ) / 3
gray = (byte)((R + G + B) / 3);
p[0] = p[1] = p[2] = gray;
p += BPP;
} // x
p += offset;
} // y
break;
case GrayMethod.WeightAveraging:
default:
for (int y = 0; y < height; y++)
{
for (int x = 0; x < width; x++)
{
R = p[2];
G = p[1];
B = p[0];
// gray = 0.3*R + 0.59*G + 0.11*B
gray = (byte)((19661 * R + 38666 * G + 7209 * B) >> 16);
p[0] = p[1] = p[2] = gray;
p += BPP;
} // x
p += offset;
} // y
break;
} // switch
}
b.UnlockBits(data);
return(b);
} // end of Gray
public static unsafe Bitmap Gray(Bitmap b, GrayMethod grayMethod)
{
byte R;
byte G;
byte B;
byte gray;
int y;
int x;
int width = b.Width;
int height = b.Height;
BitmapData data = b.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
byte * p = (byte *)data.Scan0;
int offset = data.Stride - (width * 4);
switch (grayMethod)
{
case GrayMethod.Maximum:
for (y = 0; y < height; y++)
{
x = 0;
while (x < width)
{
R = p[2];
G = p[1];
B = p[0];
gray = ((gray = (B >= G) ? B : G) >= R) ? gray : R;
p[2] = gray;
p[0] = p[1] = gray;
p += 4;
x++;
}
p += offset;
}
break;
case GrayMethod.Average:
y = 0;
while (y < height)
{
x = 0;
while (x < width)
{
R = p[2];
G = p[1];
B = p[0];
gray = (byte)(((R + G) + B) / 3);
p[2] = gray;
p[0] = p[1] = gray;
p += 4;
x++;
}
p += offset;
y++;
}
break;
default:
for (y = 0; y < height; y++)
{
for (x = 0; x < width; x++)
{
R = p[2];
G = p[1];
B = p[0];
gray = (byte)((((19661 * R) + (38666 * G)) + (7209 * B)) >> 16);
p[2] = gray;
p[0] = p[1] = gray;
p += 4;
}
p += offset;
}
break;
}
b.UnlockBits(data);
return(b);
}
