obj-C 基于索贝尔算子的彩色素描效果_sobel算子彩色-优快云博客

本文详细介绍了CImage* Sobel(CImage*)函数，用于实现图像边缘检测。通过使用Sobel算子，该函数能够识别图像中的边缘特征，并将结果以灰度图像形式返回。函数通过定义Mask矩阵、遍历图像像素并计算梯度强度来实现边缘检测。

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CImage* Sobel(CImage* image)
{
   CImage* returnImage = new	CImage();
   returnImage->Create(image->GetWidth(),
                image->GetHeight(), image->GetBPP(),0);

   matrix		GX(3,3);
   matrix		GY(3,3);
   int				sumX[3];
   int				sumY[3];
   int				SUM[3];
   int				piX = 0;
   int				piY = 0;
   int				R,G,B = 0;
   int				NC = 0;
   int				I, J = 0;
   COLORREF			pixVal;

   // Masks //////////////////////////////////////
   //X//
   GX(0,0) = -1; GX(0,1) = 0; GX(0,2) = 1;
   GX(1,0) = -2; GX(1,1) = 0; GX(1,2) = 2;
   GX(2,0) = -1; GX(2,1) = 0; GX(2,2) = 1;
   //Y//
   GY(0,0) =  1; GY(0,1) = 2; GY(0,2) = 1;
   GY(1,0) =  0; GY(1,1) = 0; GY(1,2) = 0;
   GY(2,0) = -1; GY(2,1) = -2; GY(2,2) = -1;

   for(int Y=0; YGetHeight(); Y++)  {
	for(int X=0; X < image->GetWidth(); X++)  {
	     sumX[0] = 0;sumX[1] = 0;sumX[2] = 0;
	     sumY[0] = 0;sumY[1] = 0;sumY[2] = 0;

	     if(Y==0 || Y == image->GetHeight()-1)
		 {
		      SUM[0] = 0; SUM[1] = 0; SUM[2] = 0;
		 }
		 else if(X==0 || X == image->GetWidth()-1)
		 {
		      SUM[0] = 0; SUM[1] = 0; SUM[2] = 0;
		 }
		 else
		 {
		   for(I=-1; I<=1; I++)  {
		      for(J=-1; J<=1; J++)  {
		  	  piX = J + X;
			  piY = I + Y;

			  pixVal = image->GetPixel(piX,piY);

			  R = GetRValue(pixVal);
			  G = GetGValue(pixVal);
			  B = GetBValue(pixVal);

			  sumX[0] = sumX[0] + (R) * GX(J+1,I+1);
			  sumX[1] = sumX[1] + (G) * GX(J+1,I+1);
			  sumX[2] = sumX[2] + (B) * GX(J+1,I+1);

			  sumY[0] = sumY[0] + (R) * GY(J+1,I+1);
			  sumY[1] = sumY[1] + (G) * GY(J+1,I+1);
			  sumY[2] = sumY[2] + (B) * GY(J+1,I+1);
		      }
	           }

             SUM[0] = abs(sumX[0]) + abs(sumY[0]);
	SUM[1] = abs(sumX[1]) + abs(sumY[1]);
	SUM[2] = abs(sumX[2]) + abs(sumY[2]);
         }
         if(SUM[0]>255) SUM[0]=255;
         if(SUM[0]<0) SUM[0]=0;

         if(SUM[1]>255) SUM[1]=255;
         if(SUM[1]<0) SUM[1]=0;

         if(SUM[2]>255) SUM[2]=255;
         if(SUM[2]<0) SUM[2]=0;

	int newPixel[3];
	newPixel[0] = (255 - (unsigned char)(SUM[0]));
	newPixel[1] = (255 - (unsigned char)(SUM[1]));
	newPixel[2] = (255 - (unsigned char)(SUM[2]));

	COLORREF newPixCol =  RGB(newPixel[0],newPixel[1],newPixel[2]);
	returnImage->SetPixel(X,Y,newPixCol) ;
        }
   }

   return returnImage;
}