title: RGB data limits in imshow()
body: <p>I am trying to explore hyperspectral images and how to open, read and show them. For that I am using Spectral Python (SPy). When I call <code>imshow()</code> I get RGB data limits. What do these limits represent and how are they related to the intensities in the image itself?</p>
  <pre><code>from spectral import * 
  import spectral.io.envi as envi
  import numpy as np
  import matplotlib.pyplot as plt
  img = envi.open('Image_55.hdr', 'Image_55.raw')
  
  imshow(img)
  </code></pre>
  <p>Output:</p>
  <pre><code>#ImageView object:
       Display bands       :  [0, 75, 149
       Interpolation       :  &lt;default&gt;
       RGB data limits     :
        R: [-0.04939008131623268, 9.653810501098633]
        G: [0.13590863347053528, 2.738651752471924]
        B: [0.23016303777694702, 5.807364463806152]
  </code></pre>