Mahotas – Image Stretch RGB

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In this article we will see how we can do stretching for RGB image in mahotas. Contrast stretching (often called normalization) is a simple image enhancement technique that attempts to improve the contrast in an image by `stretching’ the range of intensity values it contains to span a desired range of values, e.g. the full range of pixel values that the image type concerned allows. RGB stretching is variation of stretch() function that works per-channel on an RGB image

In this tutorial we will use “lena” image, below is the command to load it.

mahotas.demos.load('lena')

Below is the lena image

In order to do this we will use mahotas.regmin method
Syntax : mahotas.stretch_rgb(img)
Argument : It takes image object as argument
Return : It returns image object

Below is the implementation

Python3

# importing required libraries
import mahotas
import mahotas.demos
from pylab import gray, imshow, show
import numpy as np
import matplotlib.pyplot as plt
   
# loading image
img = mahotas.demos.load('lena')
   
print("Image")
   
# showing image
imshow(img)
show()
 
# stretching rgb image
new_img = mahotas.stretch_rgb(img)
  
 
# Stretched image
print("Stretched Image")
imshow(new_img)
show()

Output :

Image

Stretched Image

Another example

Python3

# importing required libraries
import mahotas
import numpy as np
from pylab import gray, imshow, show
import os
import matplotlib.pyplot as plt
  
# loading image
img = mahotas.imread('dog_image.png')
 
   
print("Image")
   
# showing image
imshow(img)
show()
 
# stretching image
new_img = mahotas.stretch_rgb(img)
  
 
# Stretched image
print("Stretched Image")
imshow(new_img)
show()