The RDP's texture memory (that the RSP had to dma a texture in to before it could be drawn) was 4kb. Yup, with a k. There were a few texture formats you could

The RDP's texture memory (that the RSP had to dma a texture in to before it could be drawn) was 4kb. Yup, with a k. There were a few texture formats you could use. 16bit RGB was the lazy choice but you could squeeze more resolution if you used 4 or 8 bit greyscale (single channel) and put colors in the vertices. You could also use palletized textures, with either 8 or 4 bit lookups (eg 256 or 16 unique colors per texture). Unfortunately that split the texture memory in half - the palette was 2kb and lookup was 2kb. If you were doing things right you spent a lot of time tweaking palettes by hand and writing code to best chose palette colors. Tldr; 48x48 16bit RGBA, 48x48 palletized 256 color RGBA, 64x64 palletized 16 color RGBA, 96x96 4 bit intensity.