vc怎么实现4Bit以及8Bit压缩和没有压缩的图片

比如说4bit未压缩的
for(i=0;i<height;i++)
{
     for(j=0;j<width/2;j++)
                {
                    p=*(bmpdata+dwLineBytes*(height-1-i)+j);
                    bw[1]=p%16;
                    p=p/16;
                    bw[0]=p;
                    for(k=0;k<2;k++)
                    {
                        *(bmpcopy+copy)=(int)quadata[bw[k]].rgbBlue;
                        copy++;
                        *(bmpcopy+copy)=(int)quadata[bw[k]].rgbGreen;
                        copy++;
                        *(bmpcopy+copy)=(int)quadata[bw[k]].rgbRed;
                        copy++;
                        *(bmpcopy+copy)=0;
                        copy++;
                        //1 循环打点显示
                    //GFMSetPixels(RGB((int)quadata[bw[k]].rgbBlue,(int)quadata[bw[k]].rgbGreen,(int)quadata[bw[k]].rgbRed),k+198+j*2,i+70,1);
                    }
                }
}


压缩的话该怎么改写代码呢？？