How do you resize an image with a desired resolution using Python?

 

Have you ever needed to resize an image for a specific purpose, like sharing it online or printing it? While many image editing programs offer tools for this, Python provides a powerful and flexible way to resize images programmatically. However, Size and DPI are related. In this post, we'll explore how to easily resize images to your desired dimensions using Python.

You can use PIL, the Python Image Library to accomplish this task easily using the following code:------------------------------------------------------

from PIL import Image 

# Open the original image 

image_path = 'path_to_your_image.jpg' 

image = Image.open(image_path) 

# Set the desired resolution (DPI) 

dpi = (300, 300) 

# Calculate the new size based on the desired DPI 

width, height = image.size 

new_width = int((width / original_dpi) * 300) 

new_height = int((height / original_dpi) * 300) 

new_size = (new_width, new_height) 

# Resize the image 

resized_image = image.resize(new_size, Image.ANTIALIAS) 

# Save the resized image with the new DPI 

resized_image.save('resized_image.jpg', dpi=dpi) 

print(f'Resized image saved as resized_image.jpg with resolution {dpi[0]}x{dpi[1]}

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I used this code to change the size and resolution of the image shown here:

The properties of this image are as shown here (72x72 DPI), 2565x2747 pixels. 

This is the code used to change resolution to 300x300 DPI:

from PIL import Image

# Open the original image
image_path = 'path_to_your_image.jpg'
image = Image.open(r'C:\Users\hoden\PycharmProjects\exploreImage\Images\OliverEdited.jpg')

# Set the desired resolution (DPI)
dpi = (300, 300)

# Calculate the new size based on the desired DPI
width, height = image.size
new_width = int((width / 72) * 300)
new_height = int((height / 72) * 300)
new_size = (new_width, new_height)

# Resize the image
resized_image = image.resize(new_size, Image.LANCZOS)

# Save the resized image with the new DPI
resized_image.save('resized_image.jpg', dpi=dpi)

print(f'Resized image saved as resized_image.jpg with resolution {dpi[0]}x{dpi[1]} DPI')

The properties of this resized image is as shown here:

The printed size of this is very large. If you happen to copy and paste these into some kind of display you may not see the size change as most display devices readjust to show the image within its visible area.  You may have to ZOOM to 100% to see on some software programs. With GIMP shown here,

You will be able to see the difference visually by using its ZOOM feature.

Resized image by the program (gimpResized.png)

Edited image (gimpEdited.png)

Printers have different designed resolutions, typically measured in dots per inch (DPI). Here are some common DPI values for various types of printers:

1. Inkjet Printers: These are commonly used for home and office printing. They typically have resolutions ranging from 300 DPI to 1200 DPI. High-end photo inkjet printers can go up to 4800 DPI or more.

2. Laser Printers: These are often used in offices for text and document printing. They usually have resolutions of 600 DPI to 2400 DPI.

3. Photo Printers: Specialized photo printers can have very high resolutions, often exceeding 4800 DPI, to produce high-quality photo prints.

4. Commercial Printers: Used for professional printing services, these printers can have resolutions of 2400 DPI or higher, depending on the type of print job and the quality required.

The DPI value indicates how many dots of ink or toner the printer can place in a one-inch line. Higher DPI values generally result in finer detail and better print quality, especially for images and photos. However, for text documents, a lower DPI (like 300 or 600 DPI) is usually sufficient.