本文将尝试使用MeanShift滤波来做磨皮算法；
MeanShiftFukunage1975The Estimation of the Gradient of a density function.
MeanShiftMeanShift
MeanShift()
Fig.1MeanShift
RadiusaaRGB
1，aRadiusRGBMc
2，(RGB)M
3，MRadiusM
4，1-3
5，图aRGBMRGBf
afafRGB
MeanShiftMeanShift
算法流程如下：
1，P(i,j)RmaxIterthreshold
2，PRSrgb()
K|x-y|
1，PM2
2，2-3maxIterPrgb
MeanShiftYCbCrY
效果图如下所示：
完整C代码如下：
#include "string.h" #include "stdio.h" #include "stdlib.h" #include "math.h" #include"f_MeanShiftFilter.h" #include"TRGB2YCbCr.h" #define MIN2(a, b) ((a) < (b) ? (a) : (b)) #define MAX2(a, b) ((a) > (b) ? (a) : (b)) #define CLIP3(x, a, b) MIN2(MAX2(a,x), b) int MeanShiftOneChannel(unsigned char* srcData, int width ,int height, int radius, int threshold, int maxIter) { int len = sizeof(unsigned long) * width * height; int i, j; int gray = 0, sum = 0, srcGray = 0, count = 0; unsigned char* tempData = (unsigned char*) malloc(sizeof(unsigned char) * height * width); memcpy(tempData, srcData, sizeof(unsigned char) * height * width); for(j = 0; j < height; j++ ) { for(i = 0; i < width; i++) { len = i + j * width; int nIter = 0, cx = 0, cy = 0, sumx = 0, sumy = 0; srcGray = tempData[len]; cx = i; cy = j; while(nIter < maxIter) { sum = 0; sumx = 0; sumy = 0; count = 0; for(int y = cy - radius; y <= cy + radius; y++) { for(int x = cx - radius; x <= cx + radius; x++) { int px = CLIP3(x, 0, width - 1); int py = CLIP3(y, 0, height - 1); len = px + py * width; gray = tempData[len]; if(abs(gray - srcGray) < threshold) { count++; sum += gray; sumx += x; sumy += y; } } } if(count == 0) break; srcGray = sum / count; cx = sumx / count; cy = sumy / count; nIter++; } srcData[i + j * width] = srcGray; } } free(tempData); return 0; }; void f_MeanShiftFilter(unsigned char* srcData, int nWidth, int nHeight, int nStride, int radius, int threshold, int maxIter) { if (srcData == NULL) { return; } if(radius == 0 || threshold == 0) return; unsigned char* yData = (unsigned char*)malloc(sizeof(unsigned char) * nWidth * nHeight); unsigned char* cbData = (unsigned char*)malloc(sizeof(unsigned char) * nWidth * nHeight); unsigned char* crData = (unsigned char*)malloc(sizeof(unsigned char) * nWidth * nHeight); unsigned char* pSrc = srcData; int Y, CB, CR; unsigned char* pY = yData; unsigned char* pCb = cbData; unsigned char* pCr = crData; for(int j = 0; j < nHeight; j++) { for(int i = 0; i < nWidth; i++) { RGBToYCbCr(pSrc[2],pSrc[1],pSrc[0],&Y,&CB,&CR); *pY = Y; *pCb = CB; *pCr = CR; pY++; pCb++; pCr++; pSrc += 4; } } MeanShiftOneChannel(yData, nWidth, nHeight, radius, threshold, maxIter); pSrc = srcData; pY = yData; pCb = cbData; pCr = crData; int R, G, B; for(int j = 0; j < nHeight; j++) { for(int i = 0; i < nWidth; i++) { YCbCrToRGB(*pY, *pCb, *pCr, &R, &G, &B); pSrc[0] = B; pSrc[1] = G; pSrc[2] = R; pY++; pCb++; pCr++; pSrc += 4; } } free(yData); free(cbData); free(crData); } 代码已经贴出来了，这里就不给DEMO了，大家可以直接使用代码进行测试，代码中YCbCr转换函数前文博客中有，或者大家自己实现，都可以。
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