OpenCV将RGB转换为YCbCr,反之亦然(Visual C ++) [英] OpenCV convert RGB to YCbCr and vice versa by hand (Visual C++)
问题描述
我想将我的rgb图片转换成ycbcr图片,反之亦然。但是有一个错误,我找不到它。
i want to convert my rgb image into a ycbcr image and vice versa by hand. But there is an mistake and I can't find it.
我的图片看起来不像他们应该。
这是我的代码:
My images don't look like they should. Here is my code:
void YCbCrToRGB(IplImage* ScrY, IplImage* ScrCb, IplImage* ScrCr, IplImage* DesR, IplImage* DesG, IplImage* DesB){
for(int i=0; i < ScrY->height; i++){
for(int j=0; j < ScrY->width; j++){
double Y = (double)(ScrY->imageData + ScrY->widthStep*i)[j];
double Cb = (double)(ScrCb->imageData + ScrCb->widthStep*i)[j];
double Cr = (double)(ScrCr->imageData + ScrCr->widthStep*i)[j];
Cb = Cb -128;
Cr = Cr -128;
int r;
int g;
int b;
(DesR->imageData + DesR->widthStep*i)[j] = (int)(1 * Y + 0 * Cb + 1.4 * Cr);
(DesG->imageData + DesG->widthStep*i)[j] = (int)(1 * Y - 0.343 * Cb - 0.711 *Cr);
(DesB->imageData + DesB->widthStep*i)[j] = (int)(1* Y + 1.765 * Cb + 0* Cr);
}}
void RGBtoYCbCr(IplImage* ScrR, IplImage* ScrG, IplImage* ScrB, IplImage* DesY, IplImage* DesCb, IplImage* DesCr){
for(int i=0; i < ScrR->height; i++){
for(int j=0; j < ScrR->width; j++){
double R = (double)(ScrR->imageData + ScrR->widthStep*i)[j];
double G = (double)(ScrG->imageData + ScrG->widthStep*i)[j];
double B = (double)(ScrB->imageData + ScrB->widthStep*i)[j];
(DesY->imageData + DesY->widthStep*i)[j] = 0.299 *R + 0.587 *G + 0.114 *B;
(DesCb->imageData + DesCb->widthStep*i)[j] = -0.1687 *R - 0.3313 *G + 0.5 *B + 128;
(DesCr->imageData + DesCr->widthStep*i)[j] = 0.5 *R - 0.4187 *G - 0.0813 *B + 128;
}
}}
int _tmain(int argc, _TCHAR* argv[])
{
try {
IplImage* img = cvLoadImage( "C:\\sad-cat.jpg",1 );
cvNamedWindow( "Example1", CV_WINDOW_AUTOSIZE );
cvShowImage( "Example1", img );
IplImage *r = cvCreateImage(cvGetSize(img), img->depth, 1);
IplImage *g = cvCreateImage(cvGetSize(img), img->depth, 1);
IplImage *b = cvCreateImage(cvGetSize(img), img->depth, 1);
cvSplit(img, b, g, r, NULL);
IplImage *y = cvCreateImage(cvGetSize(img), img->depth, 1);
IplImage *cb = cvCreateImage(cvGetSize(img), img->depth, 1);
IplImage *cr = cvCreateImage(cvGetSize(img), img->depth, 1);
RGBtoYCbCr(r,g,b,y,cb,cr);
IplImage *ycbcr = cvCreateImage(cvGetSize(img), img->depth, 3);
cvMerge(y,cb,cr,NULL,ycbcr);
cvNamedWindow( "YCbCr from RGB", CV_WINDOW_AUTOSIZE );
cvShowImage( "YCbCr from RGB", ycbcr );
YCbCrToRGB(y,cb,cr,r,g,b);
IplImage *RGBfromYCbCr = cvCreateImage(cvGetSize(img), img->depth, 3);
cvMerge(r,g,b,NULL,RGBfromYCbCr);
cvNamedWindow( "RGB from YCbCr", CV_WINDOW_AUTOSIZE );
cvShowImage( "RGB from YCbCr", RGBfromYCbCr );
cvWaitKey(0);
return 0;
}
catch( exception& e){
std::cout<<("An error occurred.") << std::endl;
std::cout << e.what() <<std::endl; // Print the error message.
cvWaitKey(0);
}
}
以下是具有语法高亮的链接: http://paste2.org/p/1569904
Here is the Link with syntax highlighting : http://paste2.org/p/1569904
我认为它的铸造错误或这样的东西。
非常感谢
I think its a casting error or something like this. THANK YOU VERY MUCH
PS:查看公式和示例图片的评论(我不允许发布超过两个链接或图片)
PS: See comments for formula and example picture (i am not allowed to post more than two links or images)
推荐答案
是的,这是一个铸造问题。
Yes, it is a casting issue.
double Y = (double)(ScrY->imageData + ScrY->widthStep*i)[j];
double Cb = (double)(ScrCb->imageData + ScrCb->widthStep*i)[j];
double Cr = (double)(ScrCr->imageData + ScrCr->widthStep*i)[j];
应为
double Y = (uchar)(ScrY->imageData + ScrY->widthStep*i)[j];
double Cb = (uchar)(ScrCb->imageData + ScrCb->widthStep*i)[j];
double Cr = (uchar)(ScrCr->imageData + ScrCr->widthStep*i)[j];
在 RGBtoYCbCr $ c的前三行中进行相同的更改$ c>。
此外,还有舍入错误。您应该在分配之前舍入结果:
Also, you have rounding errors. You should round the results before assigning:
(DesY->imageData + DesY->widthStep*i)[j] = round( 0.299 *R + 0.587 *G + 0.114 *B);
(DesCb->imageData + DesCb->widthStep*i)[j] = round( -0.1687 *R - 0.3313 *G + 0.5 *B) + 128;
(DesCr->imageData + DesCr->widthStep*i)[j] = round( 0.5 *R - 0.4187 *G - 0.0813 *B) + 128;
最后, cvMerge(r,g,b,NULL,RGBfromYCbCr) cvShowImage
cvMerge(b,g,r,NULL,RGBfromYCbCr)假设为BGR,而不是RGB。
Lastly, cvMerge(r,g,b,NULL,RGBfromYCbCr);
should be cvMerge(b,g,r,NULL,RGBfromYCbCr);
because cvShowImage
assumes BGR, not RGB.
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