How to convert PNG to JPG in Python?

Issue

I’m trying to compare two images, one a .png and the other a .jpg. So I need to convert the .png file to a .jpg to get closer values for SSIM. Below is the code that I’ve tried, but I’m getting this error:

AttributeError: ‘tuple’ object has no attribute ‘dtype’

image2 = imread(thisPath + caption)
image2 = io.imsave("jpgtest.jpg", (76, 59))
image2 = cv2.cvtColor(image2, cv2.COLOR_BGR2GRAY)
image2 = resize(image2, (76, 59))
imshow("is it a jpg", image2)
cv2.waitKey()

Solution

Before demonstrating how to convert an image from .png to .jpg format, I want to point out that you should be consistent on the library that you use. Currently, you’re mixing scikit-image with opencv. It’s best to choose one library and stick with it instead of reading in an image with scikit and then converting to grayscale with opencv.

To convert a .png to .jpg image using OpenCV, you can use cv2.imwrite. Note with .jpg or .jpeg format, to maintain the highest quality, you must specify the quality value from [0..100] (default value is 95). Simply do this:

import cv2

# Load .png image
image = cv2.imread('image.png')

# Save .jpg image
cv2.imwrite('image.jpg', image, [int(cv2.IMWRITE_JPEG_QUALITY), 100])

Answered By – nathancy

Answer Checked By – Marie Seifert (AngularFixing Admin)

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