OpenCV Error: Sizes of input arguments do not match - c++

Question

I have a strange problem. If I use cvCvtColor on an image it works but if I want to modify that image and use cvCvtColor on it there is an error:
OpenCV Error: Sizes of input arguments
do not match () in cvCvtColor, file
/build/buildd-opencv_2.1.0-3-i386-PaiiLK/opencv-2.1.0/src/cv/cvcolor.cpp,
line 2208 terminate called after
throwing an instance of
'cv::Exception'
There shouldn't be this error because I have as output:
targetImage->width =300,
targetImage->height =300 cap->width
=300, cap->height =300
that is: the size is the same. So it's nonsense..
Any idea of a possible solution?
The relevant code is here:
printf("\ntargetImage->width =%d, targetImage->height =%d ",targetImage->width,targetImage->height );
cap = cvCreateImage(cvSize(targetImage->width,targetImage->height), IPL_DEPTH_8U, 1);
cvCvtColor(targetImage, cap, CV_BGR2GRAY);//HERE NO PROBLEM
CvRect xargetRect = cvRect(0,0,300,300);
subImage(targetImage, &showImg, xargetRect);
cap = cvCreateImage(cvSize(targetImage->width,targetImage->height), IPL_DEPTH_8U, 1);
printf("\ntargetImage->width =%d, targetImage->height =%d ",targetImage->width,targetImage->height );
printf("\ncap->width =%d, cap->height =%d ",cap->width,cap->height );
cvCvtColor(targetImage, cap, CV_BGR2GRAY); //HERE THE PROBLEM
Thanks
This is the subimage code:
/// Modifies an already allocated image header to map
/// a subwindow inside another image.
inline void subImage(IplImage *dest, const IplImage *orig, const CvRect &r) {
dest->width = r.width;
dest->height = r.height;
dest->imageSize = r.height * orig->widthStep;
dest->imageData = orig->imageData + r.y * orig->widthStep + r.x * orig->nChannels;
dest->widthStep = orig->widthStep;
dest->roi = NULL;
dest->nSize = sizeof(IplImage);
dest->depth = orig->depth;
dest->nChannels = orig->nChannels;
dest->dataOrder = IPL_DATA_ORDER_PIXEL;
}

Answer 1

I now have a working dev environment, so I should post some code.
The error message in your question shows that you are using OpenCV 2.1. I tried the code sample in OpenCV 2.2 and it works just fine, your subImage seems to be working as expected. Though the CvRect &r parameter works as X,Y with width, height (as opposed to P1 to p2). Below is the code I tried (minor modifications, but very same subImage):
#include "cv.h"
#include "highgui.h"
/// Modifies an already allocated image header to map
/// a subwindow inside another image.
inline void subImage(IplImage *dest, const IplImage *orig, const CvRect &r)
{
dest->width = r.width;
dest->height = r.height;
dest->imageSize = r.height * orig->widthStep;
dest->imageData = orig->imageData + r.y * orig->widthStep + r.x * orig->nChannels;
dest->widthStep = orig->widthStep;
dest->roi = NULL;
dest->nSize = sizeof(IplImage);
dest->depth = orig->depth;
dest->nChannels = orig->nChannels;
dest->dataOrder = IPL_DATA_ORDER_PIXEL;
}
int _tmain(int argc, _TCHAR* argv[])
{
IplImage targetImage;
IplImage* showImg = cvLoadImage("c:\\image11.bmp");
//printf("\ntargetImage->width =%d, targetImage->height =%d ", targetImage->width, targetImage->height );
//IplImage* cap = cvCreateImage(cvSize(targetImage->width, targetImage->height), IPL_DEPTH_8U, 1);
//cvCvtColor(targetImage, cap, CV_BGR2GRAY);//HERE NO PROBLEM
CvRect xargetRect = cvRect(100, 100, 100, 100);
subImage(&targetImage, showImg, xargetRect);
IplImage* cap = cvCreateImage(cvSize(targetImage.width, targetImage.height), IPL_DEPTH_8U, 1);
printf("\ntargetImage->width =%d, targetImage->height =%d ", targetImage.width, targetImage.height );
printf("\ncap->width =%d, cap->height =%d ", cap->width, cap->height );
cvCvtColor(&targetImage, cap, CV_BGR2GRAY); //HERE THE PROBLEM
int result = cvSaveImage("c:\\image11.output.bmp", &targetImage);
return 0;
}