根据我在网上看到的，image stabilization最有效的算法之一是使用格雷编码的位平面匹配。但是，我无法理解它（格雷码本身并不复杂，而是其余部分）。任何人都可以向我指出一个关于这个主题的资源（或另一种稳定的稳定方法），它略低于大多数已发表论文的水平吗？示例代码胜过抽象广义方程。
出于我的目的，视频中没有平移或缩放，帧中没有移动的物体。
答案 0 :(得分：6)
你可以先尝试一些简单的方法，我最近在这里提出了一些建议：Video Stabilization with OpenCV
在你的情况下（没有平移，没有缩放，静态场景），相位相关可能已经足够并且它非常容易（参见例如维基百科）。 如果我没记错的话，有几个可用于avisynth的视频稳定滤波器/插件使用相位相关 - 你可以先试用它们。
根据我的需要，我已经实现了一个简单的工具，它可以使SURF / Homography路线对齐多个图像（对齐图像，而不是视频）。您可能想尝试一下，看看这是否满足您的需求：http://web.archive.org/web/20101004234404/http://ioctl.eu/wiki/applications/ImageAlign（嘿，我希望代码仍在运行......）
答案 1 :(得分：2)
我写了一个简单的函数来稳定视频帧的三个缓冲区，一个用于红色，绿色和蓝色。它不是最快的，但对于NTSC DVD镜架（720x480），它可以在电子机器t6412上以每秒1.7帧的速度运行。您所要做的就是在图像中心选取一个点，并通过累积每个像素匹配的位数将其与最后一帧进行比较。在嵌套循环中，对于每个循环迭代，将最近帧的搜索区域偏移一个像素。我尝试了模拟FIR相关，但这并不像使用最匹配的位选择对齐偏移那样好。此算法还使输出视频填满屏幕，而不是挥动跟随相机抖动的黑条。
#define min(a, b) (((a) < (b)) ? (a) : (b))
#define max(a, b) (((a) > (b)) ? (a) : (b))
int cubic(int x,int *v)
{
int q1,q2,q3,q4;
q1=( -1792 * v[0] + 5376 * v[1] - 5376 * v[2] + 1792 * v[3] ) >> 8;
q2=( 3840 * v[0] - 9216 * v[1] + 6912 * v[2] - 1536 * v[3] ) >> 8;
q3=( -2304 * v[0] + 2304 * v[2] ) >> 8;
q4=(v[0] + 4096 * v[1] + v[2]) >> 8;
return (((((((((q1 * x) >> 8) + q2 ) * x ) >> 8)+ q3 ) * x) >> 8) + q4 ) >> 4;
}
double get_mono_cubic_row(unsigned char * redbuf,unsigned long width, unsigned long height,signed long x,signed long y,signed int offset)
{
int m[4]={0,0,0,0};
if(x+3<width && x>=0 && y<height && y>0)
{
m[0]=redbuf[x+y*width];
m[1]=redbuf[(x+1)+y*width];
m[2]=redbuf[(x+2)+y*width];
m[3]=redbuf[(x+3)+y*width];
}
else
{
m[0]=255;
m[1]=255;
m[2]=255;
m[3]=255;
}
return cubic(offset,m);
}
unsigned char get_mono_bicubic (unsigned char *redbuf, unsigned long width,unsigned long height,double x, double y)
{
int xi=0,yi=0;
int dx=0,dy =0;
int m[4]={0.0,0.0,0.0,0.0}; /* four of one mono pixel */
xi=floor(x);
yi=floor(y);
dx=(x-xi) * 256;
dy=(y-yi) * 256;
if(yi+3<height && xi>0 && yi>0 && xi<width)
{
m[0]=get_mono_cubic_row(redbuf,width,height,xi-1,yi-1,dx);
m[1]=get_mono_cubic_row(redbuf,width,height,xi-1,yi,dx);
m[2]=get_mono_cubic_row(redbuf,width,height,xi-1,yi+1,dx);
m[3]=get_mono_cubic_row(redbuf,width,height,xi-1,yi+2,dx);
}
else
{
m[0]=255;
m[1]=255;
m[2]=255;
m[3]=255;
}
return clip(cubic(dy,m));
}
void mono_scale_exact(unsigned char *redbuf,unsigned long width, unsigned long height,unsigned long desired_width, unsigned long desired_height)
{
unsigned char *tempbuf=NULL;
double ratio_x=(desired_width * (1.0/(double)width));
double ratio_y=(desired_height * (1.0/(double)height));
unsigned long maxwidth=1;
unsigned long maxheight=1;
double u=0;
int x=0;
int y=0;
double v=0;
maxwidth=max(desired_width,width);
maxheight=max(desired_height,height);
tempbuf=(unsigned char*)malloc(maxwidth * maxheight * sizeof(unsigned char));
if(tempbuf!=NULL)
{
/* first the red */
for(y=0;y<desired_height;y++)
{
for(x=0;x<desired_width;x++)
{
u = x * (1.0/ratio_x);
v = y * (1.0/ratio_y);
tempbuf[x+y*desired_width]=get_mono_bicubic (redbuf,width,height,u,v);
}
}
for(y=0;y<desired_height;y++)
{
for(x=0;x<desired_width;x++)
{
redbuf[x+y*desired_width]=tempbuf[x+y*desired_width];
}
}
free(tempbuf);
}
}
void fatal(void)
{
exit(1);
}
#define DEBUG_STABLE 0
unsigned char digital_image_stabilization(unsigned char *redbuf, unsigned char *greenbuf, unsigned char *bluebuf,
unsigned long width, unsigned long height, unsigned short search_len,unsigned short twiddle)
{
static unsigned char *search_scratch=NULL;
static unsigned char *tempbuf=NULL;
unsigned long in_x=0;
unsigned long in_y=0;
static signed long x_adj=0;
static signed long y_adj=0;
unsigned long out_x=0;
const unsigned int mask[8]={1,2,4,8,16,32,64,128};
unsigned long out_y=0;
signed long mid_x=0;
signed long mid_y=0;
static signed long center_x=0;
static signed long center_y=0;
static signed long end_center_x=0;
static signed long end_center_y=0;
static unsigned char first=1;
int search_x=0;
int search_y=0;
unsigned long peak=0;
static int new_width=0;
static int new_height=0;
int tww_y=0;
int twp_y=0;
static unsigned long *twiddle_scratch=NULL;
if(first==1)
{
center_x=(width/2)-(search_len/2);
if(center_x<twiddle)center_x=twiddle;
center_y=(height/2)-(search_len/2);
if(center_y<twiddle)center_y=twiddle;
if((search_len+center_x)>width)fatal();
if((search_len+center_y)>height)fatal();
end_center_y=center_y+search_len;
end_center_x=center_x+search_len;
new_width=width-twiddle;
new_height=height-twiddle;
search_scratch=(unsigned char *)malloc((search_len * search_len) * sizeof(unsigned char));
tempbuf=(unsigned char *)malloc((width * height) * sizeof(unsigned char));
twiddle_scratch=(unsigned long *)malloc((twiddle * twiddle) * sizeof(unsigned long));
if(search_scratch==NULL || tempbuf==NULL || twiddle_scratch==NULL)fatal();
first=0;
}
for(search_y=0;search_y<twiddle;search_y++)
{
for(search_x=0;search_x<twiddle;search_x++)
{
twiddle_scratch[search_x+search_y]=0;
}
}
/* Multiply-accumulate */
for(mid_y=0;mid_y<twiddle;mid_y++)
{
int twp_x=0;
for(mid_x=0;mid_x<twiddle;mid_x++)
{
unsigned long acc=0;
int tw_y=0;
for(in_y=center_y;in_y<end_center_y;in_y++)
{
int tw_x=0;
for(in_x=center_x;in_x<end_center_x;in_x++)
{
unsigned long bmpptr=(in_x+mid_x)+(in_y+mid_y)*width;
unsigned int cur_gray=((((77 * redbuf[bmpptr])+(151 * greenbuf[bmpptr]) + (28 * bluebuf[bmpptr])) >> 8) & 255);
unsigned int last_gray=search_scratch[tw_x+tw_y*search_len];
acc+=(!((last_gray ^ cur_gray) & mask[0]));
acc+=(!(((last_gray ^ cur_gray) & mask[1]) >> 1));
acc+=(!(((last_gray ^ cur_gray) & mask[2]) >> 2));
acc+=(!(((last_gray ^ cur_gray) & mask[3]) >> 3));
acc+=(!(((last_gray ^ cur_gray) & mask[4]) >> 4));
acc+=(!(((last_gray ^ cur_gray) & mask[5]) >> 5));
acc+=(!(((last_gray ^ cur_gray) & mask[6]) >> 6));
acc+=(!(((last_gray ^ cur_gray) & mask[7]) >> 7));
tw_x++;
}
tw_y++;
}
//acc/=(search_len * search_len);
twiddle_scratch[twp_x+twp_y*twiddle]=acc;
twp_x++;
}
twp_y++;
}
for(search_y=0;search_y<twiddle;search_y++)
{
for(search_x=0;search_x<twiddle;search_x++)
{
if(twiddle_scratch[search_x+search_y*twiddle]>peak)
{
peak=twiddle_scratch[search_x+search_y*twiddle];
x_adj=search_x;
y_adj=search_y;
}
}
}
/* update the scratch area with the stabilized image */
tww_y=0;
for(in_y=center_y;in_y<end_center_y;in_y++)
{
int tww_x=0;
for(in_x=center_x;in_x<end_center_x;in_x++)
{
unsigned long out_bmpptr=tww_x+tww_y*search_len;
#if !DEBUG_STABLE
signed long safe_x=(in_x+x_adj);
signed long safe_y=(in_y+y_adj);
#endif
#if DEBUG_STABLE
signed long safe_x=(in_x-x_adj);
signed long safe_y=(in_y-y_adj);
#endif
unsigned long in_bmpptr=0;
unsigned char cur_gray=0;
if(safe_x<0)safe_x=0;
if(safe_y<0)safe_y=0;
in_bmpptr=safe_x+safe_y*width;
cur_gray=((77 * redbuf[in_bmpptr])+(151 * greenbuf[in_bmpptr]) + (28 * bluebuf[in_bmpptr])) >> 8;
search_scratch[out_bmpptr]=cur_gray;
tww_x++;
}
tww_y++;
}
/* move red */
for(out_y=twiddle;out_y<height;out_y++)
{
for(out_x=twiddle;out_x<width;out_x++)
{
signed long out_bmpptr=(out_x-twiddle)+(out_y-twiddle)*new_width;
#if !DEBUG_STABLE
signed long safe_x=((out_x-twiddle)+x_adj);
signed long safe_y=((out_y-twiddle)+y_adj);
#endif
#if DEBUG_STABLE
signed long safe_x=(out_x-x_adj);
signed long safe_y=(out_y-y_adj);
unsigned long bad_bmpptr=out_x+out_y*width;
#endif
signed long in_bmpptr=0;
if(safe_x<0)safe_x=0;
if(safe_y<0)safe_y=0;
if(safe_x>width)safe_x=width;
if(safe_y>height)safe_y=height;
in_bmpptr=safe_x+safe_y*width;
#if DEBUG_STABLE
tempbuf[out_bmpptr]=((safe_x>center_x-8 && safe_x<center_x+8) && (safe_y>center_y-8 && safe_y<center_y+8)) ? 255 :redbuf[bad_bmpptr];
#endif
#if !DEBUG_STABLE
tempbuf[out_bmpptr]=redbuf[in_bmpptr];
#endif
}
}
mono_scale_exact(tempbuf,new_width,new_height,width,height);
for(out_y=0;out_y<height;out_y++)
{
for(out_x=0;out_x<width;out_x++)
{
unsigned long bmpptr=out_x+out_y*width;
redbuf[bmpptr]=tempbuf[bmpptr];
}
}
/* move green */
for(out_y=twiddle;out_y<height;out_y++)
{
for(out_x=twiddle;out_x<width;out_x++)
{
signed long out_bmpptr=(out_x-twiddle)+(out_y-twiddle)*new_width;
#if !DEBUG_STABLE
signed long safe_x=((out_x-twiddle)+x_adj);
signed long safe_y=((out_y-twiddle)+y_adj);
#endif
#if DEBUG_STABLE
signed long safe_x=(out_x-x_adj);
signed long safe_y=(out_y-y_adj);
unsigned long bad_bmpptr=out_x+out_y*width;
#endif
signed long in_bmpptr=0;
if(safe_x<0)safe_x=0;
if(safe_y<0)safe_y=0;
if(safe_x>width)safe_x=width;
if(safe_y>height)safe_y=height;
in_bmpptr=safe_x+safe_y*width;
#if DEBUG_STABLE
tempbuf[out_bmpptr]=((safe_x>center_x-8 && safe_x<center_x+8) && (safe_y>center_y-8 && safe_y<center_y+8)) ? 0 :greenbuf[bad_bmpptr];
#endif
#if !DEBUG_STABLE
tempbuf[out_bmpptr]=greenbuf[in_bmpptr];
#endif
}
}
mono_scale_exact(tempbuf,new_width,new_height,width,height);
for(out_y=0;out_y<height;out_y++)
{
for(out_x=0;out_x<width;out_x++)
{
unsigned long bmpptr=out_x+out_y*width;
greenbuf[bmpptr]=tempbuf[bmpptr];
}
}
/* move blue */
for(out_y=twiddle;out_y<height;out_y++)
{
for(out_x=twiddle;out_x<width;out_x++)
{
signed long out_bmpptr=(out_x-twiddle)+(out_y-twiddle)*new_width;
#if !DEBUG_STABLE
signed long safe_x=((out_x-twiddle)+x_adj);
signed long safe_y=((out_y-twiddle)+y_adj);
#endif
#if DEBUG_STABLE
signed long safe_x=(out_x-x_adj);
signed long safe_y=(out_y-y_adj);
unsigned long bad_bmpptr=out_x+out_y*width;
#endif
signed long in_bmpptr=0;
if(safe_x<0)safe_x=0;
if(safe_y<0)safe_y=0;
if(safe_x>width)safe_x=width;
if(safe_y>height)safe_y=height;
in_bmpptr=safe_x+safe_y*width;
#if DEBUG_STABLE
tempbuf[out_bmpptr]=((safe_x>center_x-8 && safe_x<center_x+8) && (safe_y>center_y-8 && safe_y<center_y+8)) ? 255 :bluebuf[bad_bmpptr];
#endif
#if !DEBUG_STABLE
tempbuf[out_bmpptr]=bluebuf[in_bmpptr];
#endif
}
}
mono_scale_exact(tempbuf,new_width,new_height,width,height);
for(out_y=0;out_y<height;out_y++)
{
for(out_x=0;out_x<width;out_x++)
{
unsigned long bmpptr=out_x+out_y*width;
bluebuf[bmpptr]=tempbuf[bmpptr];
}
}
return (x_adj==0 && y_adj==0) ? 0 : 1;
}
要使用它，请使用图像的红色通道填充* redbuf，使用绿色通道填充* greenbuf，使用蓝色通道填充* bluebuf并调用digital_image_stabilization函数。一旦功能完成，缓冲区将具有稳定的图像。我使用了96用于search_len，32用于旋转。