Solved by ptrblck in post #2 
              
              
                Your output might be clipped to [0, 1], if you are trying to visualize floating point numbers or [0, 255] if you are using uint8. 
I cannot reproduce the issue using the latest stable releases and by making sure I’m casting to the expected type: 
img = PIL.Image.open('drums.png')
img_arr = np.array(…