These are the images from Embodiment of Scarlet Devil that contains japanese text we should translate.
The images have the alpha channel stored in a separate file called something_a.png.
The translated images can have any color depth. Some of the originals are only 16 colors, the translations doesn't need to keep this.
To try out your own changed images in the patch, create a directory called
replace_files in your game directory and put the replacement images there before applying the patch.
You should get a message towards the end showing how many files were replaced.