Covers and backgrounds

Each game can have two pictures:

Both are baseline JPEGs, because the Switch’s decoder reads no progressive JPEG. They are made with FFmpeg: scaled to fill, cut from the middle, one frame, yuvj420p. Any picture FFmpeg reads works as a source (PNG, JPEG, WebP, BMP).

Automatic pictures#

Ren’Py games ship no cover, only 16:9 menu art. The importer takes the game’s main menu art: gui.main_menu_background in gui.rpy when it is a plain string naming an image, else gui/main_menu.png, loose or inside a standard .rpa.

• The background is that art, at 640×360.
• The cover is the middle third of it. It often shows part of a background rather than the game’s title, which is why choosing your own is worth it.
• Nothing found: no pictures, and the report says Pictures: none. The loader shows a placeholder: a colour from the folder name with the title’s first letter.

Choose your own#

A real poster makes a better cover, for example a 600×900 image from SteamGridDB or a Steam capsule.

• Command line: --cover IMAGE and --backdrop IMAGE.
• Window, before export: Change cover… and Change background… on the Import page.
• Window, after export: the same buttons on a game in the Library. The picture is converted and written to the SD card or the Switch at once.
• On the Switch: Change picture on a game’s details turns a screenshot from the Album into either. See Change picture.

The manifest marks chosen pictures with "cover_custom": true and "backdrop_custom": true, and --replace keeps them. The report’s Pictures: line names the files, with (chosen) for chosen ones. A chosen picture FFmpeg cannot read is refused with its error.

What the loader accepts#

• Baseline JPEG, normally 300×450 from the importer; other sizes up to 600×900, other aspect ratios cut to their middle.
• A 24-bit BMP, which is what Change picture on the Switch writes.
• A progressive JPEG, a larger picture or an unreadable file gets the placeholder and one line in loader.log.