title: How does Keras ImageDataGenerator rescale parameter works?
body: <p>I always use this parameter to scale array of original image pixel values to be between [0,1] and specify the parameter <code>rescale=1./255</code>.</p>
  
  <p>Then when i do this:</p>
  
  <pre><code>from keras.preprocessing.image import load_img, img_to_array, ImageDataGenerator
  
  img = load_img('val_00009301.JPEG')
  img_arr = img_to_array(img)
  datagen = ImageDataGenerator(rescale=1./255)
  for batch in datagen.flow(img_arr, 
                              batch_size=1, 
                              save_to_dir='path/to/save', 
                              save_prefix='1_param', 
                              save_format='jpeg'):......`
  </code></pre>
  
  <p>When I check "path/to/save" directory, I see the picture generated by ImageDataGenerator class totally normal. How that is happen? I should see almost completely black image.</p>