Palette Limitations
The information documented here is that which was found as a result of issue #1. It was necessary before any other major work on this project took place to determine what technical limitations would have to be imposed on any new graphics, so that our lead artist could make a start on the new Pokémon battle sprites.
Issue #1 – Determine what palette limitations will be for new Pokémon sprites
This MVG video confirms what I, Andi, believed to be the case regarding colour palettes for the background and sprite layers, whereby the following limitations exist:
- Up to 8 four-colour palettes can be attributed to background tiles.
- Up to 8 four-colour palettes can be attributed to sprite tiles (although in practice this is more like 3 colours, as at least one "colour" is always used to indicate transparent pixels).
- Each background tile can use one of its 8 four-colour palettes.
- Each sprite tile can use one of its 8 four-colour palettes.
According to this Wikipedia article, the colour space available for the palettes includes a total of 32,768 colours (15-bit RGB, i.e. 5 bits per colour). Of these colours, up to 56 can be displayed on screen at any one time using standard display methods, but colours like black and white are often used in multiple palettes, due to many tiles needing them, so the total number of colours displayed at any one time (without clever coding trickery) is often less than 56 due to the repeated colours. These findings tally with MVG’s video above.
All this is also corroborated by this specification document: https://bgb.bircd.org/pandocs.htm#lcdcolorpalettescgbonly
I was pretty sure already that this was the case, but I’ve now confirmed through an emulator by disabling each layer in turn, that all battle graphics other than attack and item animations (which are done using sprites) are displayed as background graphics, which makes life much simpler.
The following sources were used to obtain this information:
- “How Graphics worked on the Nintendo Game Boy Color” video by Modern Vintage Gamer – https://www.youtube.com/watch?v=ZEJVOH6Pxkg
- “List of video game console palettes” article on Wikipedia – https://en.wikipedia.org/wiki/List_of_video_game_console_palettes#Game_Boy_Color
- “Pan Docs” documentation by Pan et al. – https://bgb.bircd.org/pandocs.htm#lcdcolorpalettescgbonly