public static unsafe void ApplyConvolution(ImageChannel <TPixel> img, ConvolutionKernel k)
{
if (img.Width < 2 || img.Height < 2)
{
return;
}
int widthTypeScaled = img.Width * img.Step;
int kernelHeight = k.Width;
int kernelWidth = k.Height;
int scale = k.Scale;
int[,] kernel = k.Kernel;
int extend = Math.Max(kernelWidth, kernelHeight) / 2;
ImageChannel <TPixel> maskImage = new ImageChannel <TPixel>(img.Width + extend * 2, img.Height + extend * 2);
FillImage(maskImage, (TPixel)0); //这里效率不高。原本只需要填充四周扩大的部分即可
CopyChannel(img, maskImage, new System.Drawing.Point(0, 0), new System.Drawing.Rectangle(0, 0, img.Width, img.Height), new System.Drawing.Point(extend, extend));
int step = img.Step;
int maskStep = maskImage.Step;
int width = img.Width;
int height = img.Height;
TPixel *start = (TPixel *)img.StartIntPtr;
TPixel *maskStart = (TPixel *)maskImage.StartIntPtr;
// 复制边界像素
TPixel *dstStart = maskStart + extend;
int maskWidth = img.Width + extend * 2;
int maskHeight = img.Height + extend * 2;
TPixel *dstContentStart = maskStart + extend + maskWidth * extend;
// 复制上方的像素
for (int y = 0; y < extend; y++)
{
TPixel *lineStart = dstStart + y * maskWidth;
TPixel *lineEnd = lineStart + width;
TPixel *copyStart = dstContentStart;
while (lineStart != lineEnd)
{
*lineStart = *copyStart;
lineStart++;
copyStart++;
}
}
// 复制下方的像素
for (int y = height + extend; y < maskHeight; y++)
{
TPixel *lineStart = dstStart + y * maskWidth;
TPixel *lineEnd = lineStart + width;
TPixel *copyStart = dstContentStart + height * maskWidth - maskWidth;
while (lineStart != lineEnd)
{
*lineStart = *copyStart;
lineStart++;
copyStart++;
}
}
// 复制左右两侧的像素
TPixel *dstLine = maskStart + maskWidth * extend;
TPixel p = default(TPixel);
for (int y = extend; y < height + extend; y++)
{
p = dstLine[extend];
for (int x = 0; x < extend; x++)
{
dstLine[x] = p;
}
p = dstLine[extend + width - 1];
for (int x = width + extend; x < maskWidth; x++)
{
dstLine[x] = p;
}
dstLine += maskWidth;
}
// 复制四个角落的像素
// 左上
p = dstContentStart[0];
for (int y = 0; y < extend; y++)
{
for (int x = 0; x < extend; x++)
{
maskStart[y * maskWidth + x] = p;
}
}
// 右上
p = dstContentStart[width - 1];
for (int y = 0; y < extend; y++)
{
for (int x = width + extend; x < maskWidth; x++)
{
maskStart[y * maskWidth + x] = p;
}
}
// 左下
p = dstContentStart[(height - 1) * maskWidth];
for (int y = height + extend; y < maskHeight; y++)
{
for (int x = 0; x < extend; x++)
{
maskStart[y * maskWidth + x] = p;
}
}
// 右下
p = dstContentStart[(height - 1) * maskWidth + width - 1];
for (int y = height + extend; y < maskHeight; y++)
{
for (int x = width + extend; x < maskWidth; x++)
{
maskStart[y * maskWidth + x] = p;
}
}
if (scale == 1)
{
for (int h = 0; h < height; h++)
{
for (int w = 0; w < width; w++)
{
TValue val = 0;
for (int kw = 0; kw < kernelWidth; kw++)
{
for (int kh = 0; kh < kernelHeight; kh++)
{
val += maskStart[(h + kh) * maskWidth + (w + kw)] * kernel[kh, kw];
}
}
start[h * widthTypeScaled + w] = (TPixel)val;
}
}
}
else
{
double factor = 1.0 / scale;
for (int h = 0; h < height; h++)
{
for (int w = 0; w < width; w++)
{
TValue val = 0;
for (int kw = 0; kw < kernelWidth; kw++)
{
for (int kh = 0; kh < kernelHeight; kh++)
{
val += maskStart[(h + kh) * maskWidth + (w + kw)] * kernel[kh, kw];
}
}
start[h * widthTypeScaled + w] = (TPixel)(val * factor);
}
}
}
maskImage.Dispose();
}
