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Exercise

Rescaling pixel intensities

Sometimes, low contrast images can be improved by rescaling their intensities. For instance, this image of Hawkes Bay, New Zealand has no pixel values near 0 or near 255 (the limits of valid intensities). (originally by Phillip Capper, modified by User:Konstable, via Wikimedia Commons, CC BY 2.0)

Hawkes Bay, New Zealand

For this exercise, you will do a simple rescaling (remember, an image is NumPy array) to translate and stretch the pixel intensities so that the intensities of the new image fill the range from 0 to 255.

Instructions
100 XP
  • Use the methods .min() and .max() to save the minimum and maximum values from the array image as pmin and pmax respectively.
  • Create a new 2-D array rescaled_image using 256*(image-pmin)/(pmax-pmin)
  • Plot the new array rescaled_image.
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