rgba to bgr conversion giving distorted image

[Source82]

In an attempt to convert to bgr for further processing with opencv I wrote this code

    cv::Mat im(imgHeight,imgWidth,CV_32FC4);
cv::Mat converted;
std::memcpy(im.data, imgCPU, imgWidth*imgHeight*sizeof(float));
cv::cvtColor(im, converted, CV_RGBA2BGR);
cv::imwrite("result.jpg",im);
cv::imwrite("result2.jpg",converted);

std::cout << "Image Saved !" << std::endl;

Unfortunetly only the top part of the image is visible the rest appears black. Help please what am I doing wrong.

[dusty-nv]

At a glance, I think you need to have imgWidth*imgHeight*sizeof(float)*4 in your 3rd line of code. Modified version is here:

std::memcpy(im.data, imgCPU, imgWidth*imgHeight*sizeof(float)*4);

[Source82]

Thanks that worked for me

[Source82]

even faster is replacing the memcpy with

  im = cv::Mat(imgHeight, imgWidth,CV_32FC4, (void *)imgCPU);

[komms]

@Source82 Thanks for the code.

Even though I used the above code, on a continous video stream, I sometimes get good images and sometimes get distorted images. Do you know, what could be the problem?

[Source82]

What is the distortion like? can you let me see the code?

[komms]

 cv::Mat im_CPU(camera->GetHeight(),camera->GetWidth(),CV_32FC4);
 cv::Mat converted_CPU;
 //std::memcpy(im_CPU.data, outCPU, camera->GetHeight()*camera->GetWidth()*sizeof(float)*4);
  im_CPU = cv::Mat(camera->GetHeight(), camera->GetWidth(), CV_32FC4, (void *)imgCPU);
  cv::cvtColor(im_CPU, converted_CPU, CV_RGBA2BGR);
  cv::imshow("converted", converted_CPU);
  cv::imwrite("RGBA_outcpu.jpg",im_CPU);
  cv::imwrite("RGB_outcpu.jpg",converted_CPU);
  std::cout << "outcpu Image Saved !" << std::endl;

[Source82]

Am quite busy now, but I will try and run your code to see if I can re-create the error. By the way, I can see you are using imshow without waitkey, you are not giving highgui time to process the draw requests from cv::imshow().

[aviontics]

I am having similar issue converting from imgRGBA to opencv mat.

Whould have thought there should be a standard function for this because it something a lot of people would want to do for further processing the detectNET camera example.

Please need help.

[aviontics]

I am having similar issue converting from imgRGBA to opencv mat.

Whould have thought there should be a standard function for this because it something a lot of people would want to do for further processing the detectNET camera example.

Please need help.

Solved the problem.
this worked for me.

    float* imgRGBA = NULL;
	void* imgCPU = NULL;
	void* imgCUDA = NULL;
	float* imgRGBAX = NULL;
	if( !camera->Capture(&imgCPU, &imgCUDA, 1000) )
		printf("\ndetectnet-camera:  failed to capture frame\n");
	
	if( !camera->ConvertRGBA(imgCUDA, &imgRGBA) ){
			printf("detectnet-camera:  failed to convert from NV12 to RGBA\n");
	}
           cv::Mat im = cv::Mat(imgHeight, imgWidth,CV_8UC3, (void *)imgCPU);