Image processing using Python Pillow

In this article, you will learn how to process and manipulate an image using the Python Pillow or PIL library.

Image processing is the technique of performing some operations on an image, in order to get an improved image or to extract some useful information from it. It is a type of signal processing in which the input is an image and the result may be an image or qualities or features related to that image. It is used to find various patterns and aspects in images. It helps to improve images for human understanding.

The Pillow and PIL (Python Imaging Library) are the same. The PIL was used with Python2. Pillow is a fork of the PIL repository which is currently compatible with Python3. This library is mostly used for image opening, processing, and transforming. It is available for Windows, Mac OS X and Linux. With the use of this library, we can also perform several image operations, like resizing, cropping, file conversion, rotating, and much more.

Pillow Installation

To install Pillow on windows, open a terminal window and run the following command.

pip install pillow

This library is pre-installed on my working system, so it returns the following-

Requirement already satisfied: pillow in c:\python37\scripts\projects\env\lib\site-packages (7.0.0)

Check Installation of Python Pillow

We can check the successful installation of Pillow by printing the installed version.

import PIL
print('Pillow Version:', PIL.__version__)

(env) c:\python37\Scripts\projects>pillow1.py
Pillow Version: 7.0.0

Python Pillow Open Image

Now, let's know how to open an image using the Pillow library. The most common module for image handling is the Image module. This module has inbuilt functions, such as loading images or creating new images, etc. Here, we have used the open() method of this module to read an image. The show() method is used to display the image.

from PIL import Image
img = Image.open('mountain.jpg')
img.show()

In the above example, we provide only the image name as the location of the image is in the same directory as the Python program, otherwise the full path of the image should be provided.

Python Pillow Get Image Mode

One image contains one mode. The image module provides the mode attribute, which tells the type and depth of the pixel in the image. Each pixel uses the full range of the bit depth. A 1-bit pixel has a range of 0-1, an 8-bit pixel has a range of 0-255, and so on. There are different modes provided by this module.

The given code returns the mode of the image using the mode() method.

from PIL import Image
img = Image.open('mountain.jpg')
print(img.mode)

RGB

Python Pillow Convert Image Mode

Python Pillow provides convert() method to convert the current mode to others. Different image mode tells the data of each image pixel differently. The following code reads an image and convert it to the specified modes. We have also saved the generated grayscale image using the save() method.

from PIL import Image
img = Image.open('mountain.jpg')

modes = ["1",'L','P','RGB','RGBA']
for m in modes:
    file_name = str(m)
    img_cov = img.convert(m)
    #show image
    img_cov.show(file_name)

Image mode 1
Image mode L
Image mode P
Image mode RGB
Image mode RGBA

Python Pillow Get Image Size

The size attribute provides the size of the image. It returns a tuple that contains width and height.

from PIL import Image

# Open Image
img = Image.open('mountain.jpg')

# getting image size
print(img.size)

(560, 334)

Python Pillow Get Image Format

The format attribute provides the format of the image file.

from PIL import Image

# Open Image
img = Image.open('mountain.jpg')

# getting image format
print(img.format)

JPEG

Python Pillow: Cropping Image

The image.crop() is used to crop the image. It crops a region from an image which is defined by a 4 tuples (left, upper, right, lower).

from PIL import Image

# Open Image
img = Image.open('mountain.jpg')
 
# Size of the image in pixels
width, height = img.size
 
# Setting the points for cropped image
left = 1
top = 2
right = 300
bottom = 300
 
# Cropped image of above dimension
img_cropped = img.crop((left, top, right, bottom))

img_cropped.show()

Python Pillow: Rotating Image

The Image.rotate() method is used to rotate an image. It takes rotation angle as an attribute and returns a rotated copy of the image.

from PIL import Image
img = Image.open('mountain.jpg')
cropped = img.rotate(180)
#show image
cropped.show()

Python Pillow: Create Thumbnail

To create thumbnail using Pillow is very simple. It provides a thumbnail() method that takes a tuple specifying the thumbnail size and converts the image to a thumbnail.

Python Pillow: Draw Shapes

With the use of Pillow module, we can also draw different shapes, like- rectangle, polygon, ellipse and so on. In the given example, we have drawn two rectangles, one polygon and one ellipse, using the ImageDraw module. This module provides simple 2D graphics for image objects.

from PIL import Image, ImageDraw

img = Image.new('RGBA', (200, 200), 'yellow')    
idraw = ImageDraw.Draw(img)
idraw.rectangle((10, 10, 100, 100), fill='blue')
idraw.rectangle((100, 100, 250, 200), fill='cyan')

idraw.polygon([(200,10), (200, 200), (150,50)], fill = 'red')
idraw.ellipse((20, 20, 90, 90), fill = 'green', outline ='black')
img.show()

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