Do these libraries PIL and OpenCV produce exactly the same image, or will there be changes in the rendered images?

 In earlier posts we have seen how images can be displayed using PIL and OpenCV.

Now the question is will these two methods look at the same input image and display the same way?

Here is the chosen image in PNG format, I just created using PAINT. The idea is colors may change, but the text will remain same.

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Using OpenCV

import cv2

# Load the image from file

image = cv2.imread(r'C:\Users\hoden\PycharmProjects\exploreImage\Images_2\RGB.png'

# Display the image in a window

cv2.imshow('Loaded Image', image)

# Wait for a key press and close the window

cv2.waitKey(0)

cv2.destroyAllWindows()

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Using PILLow or PILL

from PIL import Image

# Open an image file

image = Image.open(r'C:\Users\hoden\PycharmProjects\exploreImage\Images_2\RGB.png')

# Display the image

image.show()

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The images displayed by the two codes are as shown:

Displayed Image: Using OpenCV

Displayed Image: Using PIl

What I found using PyCharm and a chosen image was that there was no difference. They displayed the same way without any changes to color. The only difference is that the image displayed using OpenCV has a slight cut-off in the left side. This may be corrected by placing the image in the center of a predesigned canvas.

What do the AI assistants say:

However, I decided to quiz the AI tools available on the web Co_Pilot, Gemini and Meta AI.

Gemini's answer:

In most cases, these two methods will display the image with minimal to no noticeable differences. However, there are some potential scenarios where there might be slight variations:

1. Color Space:

OpenCV: By default, OpenCV loads images in BGR (Blue, Green, Red) color space.

Pillow: Pillow loads images based on the image format's native color space (usually RGB for common formats).

This difference is usually negligible for human perception, but it's important to be aware of if you're doing further processing that relies on specific color channels. You can convert the color space in OpenCV using cv2.cvtColor(image, cv2.COLOR_BGR2RGB).

note: Looks like it is not the default behaviour.

2. Alpha Channel Handling:

Images with an alpha channel (transparency information) might be handled slightly differently between the libraries. In most cases, both will display the image with transparency preserved, but there could be subtle differences in how the alpha channel information is interpreted.

3. Advanced Image Formats:

Some uncommon image formats may be supported by one library but not the other, leading to different behavior. However, common formats like JPEG, PNG, and BMP should be handled identically.

In conclusion:

For most display purposes, the two methods will produce visually identical results. However, if you need precise control over color space, alpha channel handling, or are working with uncommon formats, understanding the potential differences between OpenCV and Pillow is important.

Co-Pilot's answer:

The two methods of displaying an image using OpenCV and PIL (Pillow) will not produce exactly the same rendered image due to differences in how each library handles image loading and display. Here are the key differences:

OpenCV

Color Format: OpenCV loads images in BGR format by default. This means that the colors might appear different if you don’t convert the image to RGB before displaying it.

Display Window: OpenCV uses its own windowing system (cv2.imshow) to display images. This window is managed by OpenCV and has its own look and feel.

PIL (Pillow)

Color Format: PIL loads images in RGB format by default. This means that the colors will be displayed as expected without any need for conversion.

Display Method: PIL uses the default image viewer of your operating system to display images (image.show()). This means the image will be displayed in whatever application is set as the default for viewing images on your system.

Summary

Color Handling: OpenCV displays images in BGR format, which can cause color inversion if not converted to RGB. PIL displays images in RGB format.

Display Method: OpenCV uses its own window, while PIL relies on the system’s default image viewer

Meta AI's answer:

Do OpenCV and PIL display the same image in the same way without any color differences?

OpenCV and PIL (Python Imaging Library) handle image display differently, which can result in color differences.

*OpenCV:*

1. Default color space: BGR (Blue, Green, Red)

2. Displays images in BGR format

3. Uses cv2.imshow() function for display

*PIL:*

1. Default color space: RGB (Red, Green, Blue)

2. Displays images in RGB format

3. Uses Image.show() or Image.display() functions

Due to this difference in color spaces:

- Images displayed using OpenCV will have a different color representation compared to PIL.

It is being said that the AI agents greatly help in computer coding. I would say, although they may be working from the same databank of information, they need not provide the same answer. The developer has to know stuff beyond just the codes.

Jump to changing color with Python:

https://hodentekhelp.blogspot.com/2024/11/how-do-you-work-with-color-images-in.html