error: (-215) ssize.width > 0 && ssize.height > 0 in function resize

Understanding the OpenCV Error: “error: (-215) ssize.width > 0 && ssize.height > 0 in function resize”

This error, “error: (-215) ssize.width > 0 && ssize.height > 0 in function resize”, often pops up when working with OpenCV’s resize() function in Python. It signals a problem with the input image dimensions, specifically that either the width or height of the image is zero or negative.

Why This Error Occurs

• Empty or Corrupted Image: The most common reason is attempting to resize an image that doesn’t exist or is corrupted. Check if the image file path is correct and the image can be loaded successfully.
• Zero Dimensions: Sometimes, images might have incorrect metadata where width or height is reported as zero. This can occur during image loading or manipulation.
• Negative Dimensions: Negative dimensions are invalid in the context of image processing, indicating a potential error in the data itself.

Troubleshooting and Solutions

1. Verify Image Loading

Ensure that the image is loaded correctly. You can do this with a simple check:

import cv2

img = cv2.imread("path/to/your/image.jpg")

if img is None: print("Error: Could not load the image.")

2. Examine Image Dimensions

Before resizing, obtain the image’s width and height to make sure they are valid:

height, width = img.shape[:2]

print("Image Dimensions:", width, height)

If either dimension is zero or negative, investigate the cause.

3. Handle Invalid Input

Implement safeguards in your code to prevent resizing with invalid dimensions:

if width > 0 and height > 0: resized_img = cv2.resize(img, (new_width, new_height)) else: print("Error: Invalid image dimensions.")

4. Check for Other Errors

• File Permissions: Make sure your script has read permissions to access the image file.
• Image Format Support: Verify that OpenCV supports the image format you are using.
• Incorrect Resize Arguments: Review the arguments you’re passing to cv2.resize(), particularly the destination width and height.

Illustrative Example: Corrupted Image

In this scenario, a corrupted image file would trigger the error:

import cv2

img = cv2.imread("corrupted_image.jpg")

resized_img = cv2.resize(img, (100, 100))

Output: error: (-215) ssize.width > 0 && ssize.height > 0 in function resize 

Conclusion

The “error: (-215) ssize.width > 0 && ssize.height > 0 in function resize” error signifies a problem with the image dimensions. By carefully checking the input image, handling invalid dimensions, and addressing potential external issues, you can successfully resolve this error and perform image resizing operations.