Fixing corrupt PNGs missing the IEND chunk

Question

I have .png files outputted by a tool that converts .emfs to .pngs but that doesn't add the IEND chunk to the end.

Therefore, other tools, like ImageMagick, won't go near them as they detect them as corrupt:

> pngcheck test.png
test.png  file doesn't end with an IEND chunk

However, I can open the .png fine in desktop GUI image viewing applications, so my current workaround is to open it in these applications (e.g. Preview.app) and re-export the image, which then gets saved with the correct headers, etc.

This obviously isn't scale-able, and I need something to work server side in an automated way.

How do I go about fixing the images, preferably with a method that can be automated and run server-side, e.g. using Python?

This is the image in question.

Solution

Managed to do this in Python with:

from PIL import Image
file_in = "test.png"

img = Image.open(file_in)

file_out = "test-fixed.png"

img.save(file_out)

Requires PIL/Pillow pip install Pillow

Comments

[fixer1234]

This thread was bumped because it doesn't have an accepted answer. The question is written as a product request, so it is attracting close votes. You might want to accept your own answer.