Rescale pixel intensities of an image in Python
In this tutorial, we will see how to rescale the pixel intensities of image.
Colour images are arrays of pixel values of RED, GREEN, and BLUE. These RGB values range from 0 – 255.
Every pixel will have an RGB value depending on the intensities of these colours. Now to process these images with RGB pixel values is a huge task, especially in the field of machine learning where huge chunks of data are processed. So it is very important to rescale simpler pixel values for the ease of computation.
How to rescale pixel intensities of an image in Python?
Firstly let’s import necessary modules
import matplotlib.pyplot as plt from numpy import asarray from PIL import Image
Now we will get the image. Note that the image is in still in the form of pixels we need to convert it into arrays.
image = Image.open('image path') print(image.mode) plt.imshow(image) image_pixels=asarray(image)
Here we have used pillow module to open the image and numpy function asarray to convert into arrays.
The output looks like this
Now we will see what are the maximum and minimum and the mean pixel densities we have got.
91.78171626356098 std 255 max 0 min 109.53139837139598 mean
Since we have got the mean values we will subtract the mean value from all the pixel values.
And then divide them by the standard deviation of the pixel values.
Now we have got the rescaled pixel values.