title: numpy where RGB channel greater than [0,0,0]
body: <p>Trying to find colors that are not equal black and I need fastest way to do that. Strangle, the code below works for conditions !=. It doesnt work for > or =. Also I dont want to sum the channel and search for values greater than 0 (thats too slow)</p>
  
  <pre><code>import numpy as np
  x = np.zeros(shape=[2,10,3])
  x[0,0]=np.array([0,0,255])
  x[0,5]=np.array([255,0,0])
  x[0,8]=np.array([255,0,0])
  x[0,9]=np.array([255,0,0])
  x[1,2]=np.array([0,0,255])
  x[1,1]=np.array([255,0,0])
  x[1,9]=np.array([255,0,0])
  x[1,6]=np.array([255,0,0])
  
  indices=(np.where(np.all(x[0,:]!=[0,0,0],axis=-1),))
  print('values',x[i])
  
  &gt;&gt; []
  </code></pre>
  
  <p>Thanks for advice in advance</p>