原理为：将原始图像的每个像素通过一个比例关系式映射到相应的位置。


1 /*  2  lrgb:   input 24bits rgb buffer  3  srgb:   output 24bits rgb buffer  4  width:  input width  5  height: input height  6  xscale: changed vector  7  yscale: changed vector  8  */  9 int lrgbtosrgb(unsigned char *lrgb, unsigned char *srgb, int width, int height, float xscale, float yscale) 10 { 11     int in = 0, out = 0; 12     int ox, oy;     //the pixel site is after changed 13     int rx, ry;     //the pixel site is before changed 14     int temp = 0;   //turn site(x,y) to memory storage 15     int outwidth = width * xscale;      //after changed width 16     int outheight = height * yscale;    //after changed height 17  18     //rx = ox/xscale + 0.5;// out--to--input 19     //ry = oy/yscale + 0.5;// out--to--input 20  21     for (oy = 0; oy < outheight; oy++) 22     { 23         ry = (int)(oy/0.5 + 0.5); 24         if(ry >= height) 25         ry--; 26         temp = ry * width *3;//origion pixel site of which width 27  28         for (ox = 0; ox < outwidth; ox++) 29         { 30             rx = (int)(ox/0.5 + 0.5); 31             if (rx >= width) 32                 rx--; 33             in = temp + rx * 3;//change site(x,y) to storage 34  35             srgb[out+0] = lrgb[in+0]; 36             srgb[out+1] = lrgb[in+1]; 37             srgb[out+2] = lrgb[in+2]; 38  39             out += 3; 40         } 41     } 42     return 0; 43 }