Automatic .png export setting on batch resize removes alpha channel

[Eugen-Stimac]

What went wrong?
Batch rescale doesn't keep the same image mode on .png files with 'automatic' export settings.
Transparency was removed (like alpha channel was gone), and it seems when export setting was set to 8bit rgba instead of automatic - everything worked fine. Basically, 'automatic' doesn't detect the mode properly for images.

What should be the expected behavior?
Should keep the same mode/profile (8bit rgba as 8bit rgba for example).

If you can, specify the steps to reproduce the problem.
Batch convert .png files with only scale to 50% and cubic interpolation. No conditions or anything.

Configuration
Version of Batcher: latest (1.1.1)
Version of GIMP: 3.0.6
Operating system:
Win10 "installer from gimp.org"

Additional information
The images were 8 .png files, black & white - black semi-transparent lines on transparent BG.

[kamilburda]

Hi, thanks for the report. I tried reproducing this, but I was able to export a PNG with preserved transparency.

Does this happen only with Batcher or also when you export the image in GIMP (File -> Export As...)?

Can you provide a settings file (Settings -> Save Settings to File...) and an incrimintating input image? It could help me narrow down the issue.

[Eugen-Stimac]

Hey! It happens only with Batcher. You can try on the image attached here.
I've also made a screenshot of the settings - the PNG export format set to Automatic seems to not catch the export correctly. It only seems to happen when working with images that have a single color and transparency of varying amplitude, from what I've seen.

Try exporting manually from GIMP to 50% scale, and with Batcher to same scale, and you'll see the difference.

[kamilburda]

Alas, I couldn't reproduce this on my end with the same setup and the attached image. Can you try resetting settings and see if the problem persists?