[COLOR] Images without an alpha channel output black when transformed

Commit Hash 8ac191ce (AppImage from Github releases)

Platform Arch Linux

Summary When using a JPEG image, or a PNG image with no alpha channel as a source media:

• applying the Opacity node will fade the image to black rather than make it transparent;
• applying the Corner Pin node will output black between the target quadrilateral and the rectangular frame.

Other nodes that can output transparent pixels are likely affected as well, though I haven't tested extensively.

Notably, this does not occur when the source is an MP4 video, despite the format not supporting alpha either. I suspect whatever step of the processing pipeline adds an alpha channel to input videos is simply missing for images.

Additional Information / Output

Very crude example: I applied the same (copy pasted) Corner Pin node to three media containing a solid green square: an MP4 video (top), a PNG image with an alpha channel (bottom left), and a PNG image without an alpha channel (bottom right).