Strange PNG on export about bdsup2sub HOT 4 OPEN

I tried to reproduce your issue as follows:

• open a blu-ray or a dvd subtitle file file with BDSup2Sub
• export it as xml/png
• open any of the exported png images with the default image viewer under Ubuntu (Gnome Image Viewer) and check for transparency
• open any of the exported png images with Gimp 2.8 and check for alpha channel existence (Layer/Transparency/Remove alpha channel should be active; after removing the alpha channel the transparency should be gone)

In all my tests the alpha channel was there.

Do you experience this issue with a specific subtitle file?
Can you try with the latest stable or development version of BDSup2Sub: https://github.com/mjuhasz/BDSup2Sub/downloads

from bdsup2sub.

After a lot of searching i found out there are kinda special PNG encodings within the SUPs. SuperPNG is a Plugin in Photoshop, which makes it possible to open and save 8bit PNG with alpha channel. Since this is not supported in Photoshop u will loose opacity informations when opening the files.
Maybe u should offer a conversion to "default" 32bit PNG or someone should check if the newer PS version support it.

from bdsup2sub.

You ran into the issue described here: https://github.com/mjuhasz/BDSup2Sub/wiki/Supported-Formats

"Note that BDSup2Sub will only export 8bit palettized PNGs with transparency (via tRNS tag) for maximum compatibility with Sonic Scenarist HDMV. Unfortunately, only a few (free) graphic programs support this format correctly. Paint.NET however seems to work just fine."

Indeed, Photoshop cannot open indexed color PNG files that have indexed transparency because it just doesn't fit with Photoshop's image modes. GIMP has the 'Indexed' option under Image/Mode and seems to work well. I get an alpha channel even after exporting and reopening the file (at least under Gimp 2.8).

At the moment I have no plans to change the png format. I have no access to authoring tools so I cannot test the compatibility with them. There are image editors that can handle the indexed png format and I wouldn't want to break the compatibility with authoring tools or the existing workflow of people using the xml/png export feature.

from bdsup2sub.

What will happen if i import PNG32? I noticed problems with colored PNG8+Alpha and the XBMCv11 (didn't tried v12 yet). There seems to be a palette problem - the colors are wrong.

from bdsup2sub.