我试着写一个YUV422到RGB24的转换器,但转换后的数据的结果似乎很奇怪。 结果是紫色触摸的灰度图片带有一些浅绿色点...... 有没有人有想法?
inline void convert_yuv442_2_rgb24(const unsigned char* source, unsigned char* destination, unsigned long width, unsigned long height)
{
unsigned char data[3];
for(unsigned long i = 0, c = 0; i < width * height * 2; i += 2, c += 3)
{
// 16Bit YUV422 -> 24Bit YUV
data[0] = source[i+0];
data[1] = (source[i+1] & 0xF0) >> 4;
data[2] = (source[i+1] & 0X0F);
// YUV-> RGB24
//destination[c + 0] = (float) (1.164f*(data[0] - 16) + 1.596f*(data[2] - 128));
//destination[c + 1] = (float) (1.164f*(data[0] - 16) - 0.813f*(data[2] - 128) - 0.391f*(data[1] - 128));
//destination[c + 2] = (float) (1.164f*(data[0] - 16) + 2.018f*(data[1] - 128));
destination[c + 0] = (float) data[0] + (float) data[2] / 0.877F;
destination[c + 2] = (float) data[0] + (float) data[1] / 0.493f;
destination[c + 1] = (float) 1.7f * (float) data[0] - 0.509f * destination[c + 0] - 0.194f*(float)destination[c + 2];
}
}
我用给定的提示尝试了另一个人。 转换器代码来自此处:http://paulbourke.net/dataformats/yuv/
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <libv4l1.h>
#include <libv4l2.h>
#include <linux/videodev.h>
int init_webcam( int *fd, struct video_window *web_win, long *length);
struct RGB
{
unsigned char r, g, b;
};
RGB convert(int y, int u, int v)
{
RGB rgb;
u -= 128;
v -= 128;
rgb.r = y + 1.370705 * v;
rgb.g = y - 0.698001 * v - 0.337633 * u;
rgb.b = y + 1.732446 * u;
if (rgb.r < 0) rgb.r = 0;
if (rgb.g < 0) rgb.g = 0;
if (rgb.b < 0) rgb.b = 0;
if (rgb.r > 255) rgb.r = 255;
if (rgb.g > 255) rgb.g = 255;
if (rgb.b > 255) rgb.b = 255;
return rgb;
}
void YUV422_2_RGB24(unsigned char* yuv, RGB* p1, RGB* p2)
{
// int u = yuv[0];
// int y1 = yuv[1];
// int v = yuv[2];
// int y2 = yuv[3];
int y1 = yuv[0];
int u = yuv[1];
int y2 = yuv[2];
int v = yuv[3];
*p1 = convert(y1, u, v);
*p2 = convert(y2, u, v);
}
int main()
{
struct video_window web_win;
int fd;
long length;
if( !init_webcam( &fd, &web_win, &length))
return 1;
// Bild aufnehmen
unsigned char* picture = new unsigned char[web_win.width * web_win.height * 2];
unsigned char* image = new unsigned char[web_win.width * web_win.height * 3];
if( v4l1_read(fd, picture, web_win.width * web_win.height * 2) == -1)
{
printf( "Error while reading webcam\n");
return 0;
}
// Bild speichern
FILE *imagefile;
if((imagefile = fopen( "bild.ppm", "w+b")) == NULL)
{
printf("Couldn't open file for writing\n");
return 0;
}
RGB p1, p2;
for(unsigned long i = 0, c = 0; i < web_win.width * web_win.height * 2; i += 4, c += 6)
{
YUV422_2_RGB24(&picture[i], &p1, &p2);
image[c + 0] = p1.r;
image[c + 1] = p1.g;
image[c + 2] = p1.b;
image[c + 3] = p2.r;
image[c + 4] = p2.g;
image[c + 5] = p2.b;
}
fprintf( imagefile, "P6\n%d %d\n255\n", web_win.width, web_win.height);
for(unsigned long i = 0; i < web_win.width * web_win.height; ++ i)
{
fwrite((unsigned char*) &image[i * 3], 1, 3, imagefile);
}
fclose(imagefile);
delete[] picture;
delete[] image;
v4l1_close( fd);
return 0;
}
int init_webcam( int *fd, struct video_window *web_win, long *length)
{
struct video_capability web_cap;
struct video_picture web_pict;
if((*fd = v4l1_open("/dev/video0", O_RDONLY)) == -1)/*Open webcam device*/
{
printf( "Unable to open webcam devide\n");
return 0;
}
if( v4l1_ioctl( *fd, VIDIOCGPICT, &web_pict) == -1)/*This function call isn't necessary but otherwise you won't get a proper picture*/
{
printf( "Unable to get picture information\n");
return 0;
}
if (ioctl (*fd, VIDIOCGPICT, &web_pict) != -1)
{ // successfully retrieved the default image properties
// the following values are for requesting 8bit grayscale
//web_pict.depth = 16;
web_pict.palette = VIDEO_PALETTE_YUV422;
if (ioctl (*fd, VIDIOCSPICT, &web_pict) == -1)
{
printf("failed to set the image properties\n");
//return 0;
}
}
if( ioctl( *fd, VIDIOCGCAP, &web_cap) == -1)/*Get video capabilities*/
{
printf( "Unable to get capabilities\n");
return 0;
}
if( v4l1_ioctl( *fd, VIDIOCGWIN, web_win) == -1)/*Get video information*/
{
printf( "Unable to get video information\n");
return 0;
}
web_win->width = web_cap.maxwidth;/*Try to write max solution*/
web_win->height = web_cap.maxheight;
if( v4l1_ioctl( *fd, VIDIOCSWIN, web_win) == -1)/*Write new(?!) video information*/
{
printf( "Unable to write video information\n");
return -1;
}
if( v4l1_ioctl( *fd, VIDIOCGWIN, web_win) == -1)/*Read new(?!) video information*/
{
printf( "Unable to get video information\n");
return 0;
}
*length = web_win->width * web_win->height * (web_pict.depth/8);
printf("bits per pixel: %d\n", web_pict.depth);
printf("palette: %d\n", web_pict.palette);
return 1;
}
答案 0 :(得分:2)
YUV 422将2个像素编码为4个字节。您的代码将3个字节解码为1个像素,因此完全关闭。请参阅维基百科上的说明:http://en.wikipedia.org/wiki/YUV#Y.27UV422