PC Engine Graphics Summary
The PC Engine can generate up to 64 sprites and a background layer.
There are 512 available colors, which you can see here:
http://img402.imageshack.us/img402/4139/pcenginecolourpalette.png
Note: With this color selection you can’t use rgb(255,255,255) for white, which is slightly annoying. If it’s important to you to use actual white, then use it in lieu of the available “white” in that file--but then you have to remember that white is out-of-step with the other 9-bit colors!
32 color palettes are available at a given time:
Palettes 0-15 are for background tiles
Palettes 16-31 are for sprites
Each palette has 16 colors, but for sprites the first color is used for transparent pixels--so you only actually have 15 colors available for a given sprite. Background tiles have all 16 colors available.
Note: For sprites and tiles that share palettes, please make sure that all colors are in a consistent order!
Each sprite can have one of the following sizes: 16x16, 16x32, 16x64, 32x16, 32x32, 32x64. Larger objects can be built with multiple sprites.
A maximum of 256 pixels per scanline (horizontal row of pixels) can be displayed simultaneously. If that limit is exceeded then the lowest-priority sprites start getting dropped. [I think this pixel limit includes transparent pixels but I’m not 100% sure about that, I’ll fact check this.]
The background is built using either 8x8 tiles or 16x16 tiles (but not both). Each background can use up to 256 unique tiles, and each individual tile has its own “palette” index attached to it--which refers to one of the 16 available background tiles.
Tiles are arranged in a “map” that is a maximum of 256 tiles wide and 256 tiles tall, the viewable portion of which is the background visible on-screen. Speaking of which, the viewable area of the PCE’s “normal” resolution is 256x224. The PC Engine will output more pixels into the overscan area, 282x242 in its low-resolution mode, but we will only make use of 256x224. (There is also a high-res mode of 565x242.)
The background can have up to four independently-scrolling areas (this is a HuC limitation).
Apparently you can also have an additional “background layer” made of the background color. (http://www.pcenginefx.com/forums/index.php?topic=17643.msg370401#msg370401)
