c++ - 访问负像素值 OpenCV

Question

IplImage* pRGBImg = cvLoadImage(input_file.c_str(), CV_LOAD_IMAGE_UNCHANGED); 
int width = pRGBImg->width; 
int height = pRGBImg->height;
int bpp = pRGBImg->nChannels; 
for (int i=0; i < width*height*bpp; i+=bpp) 
{
  if (!(i % (width*bpp))) // print empty line for better readability
      std::cout << std::endl;

  std::cout << std::dec << "R:" << (int) pRGBImg->imageData[i] <<  
                          " G:" << (int) pRGBImg->imageData[i+1] <<  
                          " B:" << (int) pRGBImg->imageData[i+2] << " "; 
}

这段代码给出了不同的像素值，我在 matlab 中得到的值是正值，而 open cv 给出的值是负值。

Answer 1

您可能正在将一个带符号的字节值转换为 int，它可以给出负值。试试这个代码:

  std::cout << std::dec << "R:" << (unsigned int) pRGBImg->imageData[i] <<  
                          " G:" << (unsigned int) pRGBImg->imageData[i+1] <<  
                          " B:" << (unsigned int) pRGBImg->imageData[i+2] << " ";