Bug:failed generate png picture thumbnail but some others succeed

[hatcherfang]

Description and expectations

I generate some png files' thumbnail failed, but some others succeed when I use the manager.get_jpeg_preview.

How to reproduce

from preview_generator.manager import PreviewManager

path = '/tmp/IMG20200422_094758.png'                                                  
cache_path = "/tmp/cache/"                                                            
manager = PreviewManager(cache_path, create_folder=True)                              
path_to_preview_image = manager.get_jpeg_preview(path, force=True)

the image as below:

but the other image is ok as below:

Version information

• Version: [0.23]
• Device / System: [Debian Buster]

[raphj]

Is there an error message?

[hatcherfang]

Is there an error message? Yes, the error message is as below:

File "test3.py", line 7, in <module>
path_to_preview_image = manager.get_jpeg_preview(path, force=True)
File "/usr/local/lib/python3.6/site-packages/preview_generator/manager.py", line 203, in get_jpeg_preview
mimetype=preview_context.mimetype,
File "/usr/local/lib/python3.6/site-packages/preview_generator/preview/builder/image__imconvert.py", line 131, in build_jpeg_preview
source_path=file_path, dest_path=tmp_png.name, mimetype=mimetype
File "/usr/local/lib/python3.6/site-packages/preview_generator/preview/builder/image__imconvert.py", line 164, in _imagemagick_convert
stderr=STDOUT,
File "/usr/local/lib/python3.6/subprocess.py", line 311, in check_call
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['convert', 'png:/tmp/IMG20200422_094758.png', '-layers', 'merge', '/tmp/preview-generator-y7qu4wdy.png']' returned non-zero exit status 1.

[Felti]

i got the same error for PNG some get converted and some not

[raphj]

What happens if you run the given convert command manually? Is there a meaningful error?

convert png:/tmp/IMG20200422_094758.png -layers merge /tmp/preview-generator-y7qu4wdy.png

[Felti]

i did some tests, it appear that when the image have been converted to something other than it's original extension, it triggers the errors, must be something related to the mimeType check (ex : .png , image/jpg), otherwise when the file/img extension is the same as the mimeType (ex : .png , image/png) it doesn't

[raphj]

So you run into errors when attempting to preview a .png file which is actually a JPEG image, is that it? Do I understand correctly?

@hatcherfang is /tmp/IMG20200422_094758.png indeed a PNG image or is it actually a JPG image? GitHub actually did a jpeg preview for your image.

[Felti]

So you run into errors when attempting to preview a .png file which is actually a JPEG image, is that it? Do I understand correctly?

yes indeed

[raphj]

Is it acceptable for you to use the extension that matches the right mime type, or perhaps no extension at all if difficult? Indeed the wrong extension will confuse the various tools we use to detect types.

@inkhey we have an error when attempting to convert a file that does not have the correct extension.

Le 06/09/2021 à 16:20, Mad Tofu a écrit :

So you run into errors when attempting to preview a .png file
which is actually a JPEG image, is that it? Do I understand correctly?

yes indeed

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