RGB格式等比例缩放

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。

 /*
  lrgb:   input 24bits rgb buffer
  srgb:   output 24bits rgb buffer
  width:  input width
  height: input height
  xscale: changed vector
  yscale: changed vector
  */
 int lrgbtosrgb(unsigned char *lrgb, unsigned char *srgb, int width, int height, float xscale, float yscale)
 {
     int in = , out = ;
     int ox, oy;     //the pixel site is after changed
     int rx, ry;     //the pixel site is before changed
     int temp = ;   //turn site(x,y) to memory storage
     int outwidth = width * xscale;      //after changed width
     int outheight = height * yscale;    //after changed height

     //rx = ox/xscale + 0.5;// out--to--input
     //ry = oy/yscale + 0.5;// out--to--input

     for (oy = ; oy < outheight; oy++)
     {
         ry = (int)(oy/0.5 + 0.5);
         if(ry >= height)
         ry--;
         temp = ry * width *;//origion pixel site of which width

         for (ox = ; ox < outwidth; ox++)
         {
             rx = (int)(ox/0.5 + 0.5);
             if (rx >= width)
                 rx--;
             in = temp + rx * ;//change site(x,y) to storage

             srgb[out+] = lrgb[in+];
             srgb[out+] = lrgb[in+];
             srgb[out+] = lrgb[in+];

             out += ;
         }
     }
     return ;
 }