Hacking NEC PC Games/Figuring out Image Formats

Before you do anything...

First look around and see if what you need to do is already done. The Japanese love hacking their games, and have created [| quite a few means to do so]. The Susie project in particular has plugins for many formats. Many games already have all the CG scenes extracted or screen-shotted and you can find these on image sites. If you can't find what you want in an existing tool, you'll have to make one, which likely means working out its format.

Image coding basics

NEC PC image data are stored in terms of the data format of the video modes they are made for. That tends to mean 3-bit or 4-bit planar depending on the color depth. To save space, and improve loading speed, images may be compressed using one of three basic techniques known in the late 80s/early 90s. For more information, see Hacking NEC PC Games/Dealing With Compressed Data.