Negative Transformation of an Image in Python

In this article, you will learn how to use PIL in Python to perform a negative transformation on an image. PIL is an abbreviation for Python Imaging Library. This library is used for multiple image transformations. PIL makes it super easy to work with images and can help you edit different parts of it without many lines of code.

Importing Modules

Let’s use the Image Class from the PIL for this purpose. As a result, the first line of the script will be as follows:

from PIL import Image

Image Class is made up of many properties and methods in this case. To open an image, see an image, retrieve pixels from a given image, and change pixels in an image, we require open, show, getpixel, and putpixel methods.

So, let’s have a look at how to open an Image. It is possible to do so as follows.

from PIL import Image
import matplotlib.pyplot as plt
img=Image.open("fig.jpg")
plt.axis('off')
plt.imshow(img)

Loading The Image

Here, img is the Image Object for the supplied image, which can be found at a path of the Image.” Let’s look at the Negative Transformation of Colors in an Image.

As we all know, under the RGB color model, each color has a decimal index ranging from 0-255. The value 0 represents the lowest and the value 255 represents the highest. For example, (255,255,255) denotes white.

Similarly, (0,0,0) represents black. We are meant to conduct the Negative Transformation of the Color, which implies inverting the color as seen below.

Let Colour X is represented as (r,g,b)=(100,100,100). It can be transformed as follows

R=255-r =255-100=155 => R=155
Similarly, G=155 and B=155
Hence Negatively Transformed Colour Indices of X are (R,G,B) =(155,155,155)

Implementing Negative Transformation of an Image

So, let’s implement a Negative Transformation of Colours for each Pixel of an Image.

w,h=img.size
for i in range(w):
    for j in range(h):
        r,g,b=img.getpixel((i,j))
        r=255-r
        g=255-g
        b=255-b
        img.putpixel((i,j),(r,g,b))
plt.axis('off')
plt.imshow(img)

Code for Negative Transformation of Images in Python

from PIL import Image
import matplotlib.pyplot as plt
img=Image.open("fig.jpg")

w,h=img.size
for i in range(w):
    for j in range(h):
        r,g,b=img.getpixel((i,j))
        r=255-r
        g=255-g
        b=255-b
        img.putpixel((i,j),(r,g,b))
plt.axis('off')
plt.imshow(img)

Conclusion

Congratulations! You just learned how to get the Negative Transformation of an Image. Hope you enjoyed it! 😇

Liked the tutorial? In any case, I would recommend you to have a look at the tutorials mentioned below:

Thank you for taking your time out! Hope you learned something new!! 😄