我正在根据颜色跟踪对象,并且我正在使用 EmguCV 库将我的彩色图像阈值设置为二进制黑白图像。阈值处理本身非常快,在 320x240 图像上为 50 毫秒。我使用的是 RG Chromaticity 颜色空间,所以有一些必要的计算。
现在我正在尝试使用指针来加速它,但结果与我对 emguCV 所做的非常相似(每张图像大约 50 毫秒)。
我想问一下,如果有专家可以帮助我,我做错了什么。这是我的颜色阈值实现的简短代码片段。它基于这个:https ://web.archive.org/web/20140906075741/http://bobpowell.net/onebit.aspx 。
public static Bitmap ThresholdRGChroma(Bitmap original, double angleMin,
double angleMax, double satMin, double satMax)
{
Bitmap bimg = new Bitmap(original.Width, original.Height, PixelFormat.Format1bppIndexed);
BitmapData imgData = original.LockBits(new Rectangle(0, 0, original.Width, original.Height), ImageLockMode.ReadOnly, original.PixelFormat);
BitmapData bimgData = bimg.LockBits(new Rectangle(0, 0, bimg.Width, bimg.Height), ImageLockMode.ReadWrite, bimg.PixelFormat);
int pixelSize = 3;
double r, g, angle, sat;
unsafe
{
byte* R, G, B;
byte* row;
int RGBSum;
for (int y = original.Height - 1; y >= 0; y--)
{
row = (byte*)imgData.Scan0 + (y * imgData.Stride);
for (int x = original.Width - 1; x >= 0; x--)
{
// get rgb values
B = &row[x * pixelSize];
G = &row[x * pixelSize + 1];
R = &row[x * pixelSize + 2];
RGBSum = *R + *G + *B;
if (RGBSum == 0)
{
SetIndexedPixel(x, y, bimgData, false);
continue;
}
//calculate r ang g for rg chroma color space
r = (double)*R / RGBSum;
g = (double)*G / RGBSum;
//and angle and saturation
angle = GetAngleRad(r, g) * (180.0 / Math.PI);
sat = Math.Sqrt(Math.Pow(g, 2) + Math.Pow(r, 2));
//conditions to set pixel black or white
if ((angle >= angleMin && angle <= angleMax) && (sat >= satMin && sat <= satMax))
SetIndexedPixel(x, y, bimgData, true);
else
SetIndexedPixel(x, y, bimgData, false);
}
}
}
bimg.UnlockBits(bimgData);
original.UnlockBits(imgData);
return bimg;
}
private unsafe static void SetIndexedPixel(int x, int y, BitmapData bmd, bool pixel)
{
int index = y * bmd.Stride + (x >> 3);
byte* p = (byte*)bmd.Scan0.ToPointer();
byte mask = (byte)(0x80 >> (x & 0x7));
if (pixel)
p[index] |= mask;
else
p[index] &= (byte)(mask ^ 0xff);
}
private static double GetAngleRad(double x, double y)
{
if (x - _rgChromaOriginX == 0)
return 0.0;
double angle = Math.Atan((y - _rgChromaOriginY) / (x - _rgChromaOriginX)); // 10ms
if (x < _rgChromaOriginX && y > _rgChromaOriginY)
angle = angle + Math.PI;
else if (x < _rgChromaOriginX && y < _rgChromaOriginY)
angle = angle + Math.PI;
else if (x > _rgChromaOriginX && y < _rgChromaOriginY)
angle = angle + 2 * Math.PI;
return angle;
}