Error handling for unsupported transparency

[HTYISABUG]

Description

When input images (palette mode) have transparency (bytes) in info, the output images (RGB mode) will inherit it, causing ValueError in Pillow:PIL/PngImagePlugin.py#1364 when trying to unpack this bytes.

This commit check the PNG mode and transparency info, removing transparency if it's RGB mode and transparency is bytes

Reproduce

Test file

1. Goto Extras
2. Goto Batch Process
3. Run process on test file

Screenshots/videos:

Before

After

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests

[AUTOMATIC1111]

I get

A:\programs\Python310\lib\site-packages\PIL\Image.py:992: UserWarning: Palette images with Transparency expressed in bytes should be converted to RGBA images

But no error. Using Pillow 9.5.0 as specified in the requirements file.

[HTYISABUG]

I get

A:\programs\Python310\lib\site-packages\PIL\Image.py:992: UserWarning: Palette images with Transparency expressed in bytes should be converted to RGBA images

But no error. Using Pillow 9.5.0 as specified in the requirements file.

Strange.

I'm sure I am using Pillow 9.5.0,
and what Pillow do after the warning you get is similar to my patch.

I will check the reason, thanks for review.

[AUTOMATIC1111]

Managed to reproduce it.