CODEWITHSUNDEEP
pythonopencvruntime-errorpnglibpng
Semnodime
Semnodime

Reputation: 2003

libpng error: Read Error / Why can't this image be processed by OpenCV?

Why can't this specific test.png image be processed by OpenCV? Note: I posted a workaround, but I am still interested in what the actual cause of the error is.

import cv2
cv2.imread('test.png')

results in libpng error: Read Error, while other .pngs get processed without error.

Context

cv2.version.opencv_version == '4.5.5.62' installed via pipenv install opencv-python on python 3.8

Test image

(test.png)

Upvotes: 0

Views: 2536

Answers (1)

Semnodime
Semnodime

Reputation: 2003

I noticed that version of libpng is 15.13.0 according to the file name of lib/python3.8/site-packages/opencv_python.libs/libpng15-ce838cd1.so.15.13.0

Apparently, it's a bug in an older version of libpng, as PIL/pillow using libpng16 (Pillow.libs/libpng16-213e245f.so.16.37.0) works just fine.

# instead of:
# image = cv2.imread(img_name)

# use:
image = Image.open(img_name)

# Convert Image to numpy array
# It's not the most efficient way, but it works. *(link¹)
image = np.asarray(image)

# Remove alpha channel if existent
if len(image.shape) == 3 and image.shape[2] == 4:
    image = image[:, :, : 3]

# Restore RGB colors
image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)

References:

Performance: https://uploadcare.com/blog/fast-import-of-pillow-images-to-numpy-opencv-arrays/

Upvotes: 2

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