title: What's the meaning of the values in the OpenCV image representation?
body: <p>I am using OpenCV with Python. When I load a JPG or PNG image by calling <code>cv2.imread()</code>, I get a 2D matrix, whose size is the same as the resolution of that image. Each number in the matrix is in the range of 0 to 255.</p>
  
  <p>I don't understand how this matrix can represent an image. In particular, I expect to see a 3D matrix, whose third dimension represents RGB channels. If a pixel is represented by one 8-bit integer, then the whole image can only have 256 colors, but it is clearly not true.</p>
  
  <p>What am I missing here?</p>