DuncanVanTrigt,
The Interlaced screen mode for MSX2 screen modes is written in the Todo (but I have not idea if it will be done one day).
Dace,
See the manual in page 13 ('How to create the image of a MSX media?').
You need 'grit' utility that is included with devkitARM.
A dithering Software is recommended.
Summary of Method:
1/ Convert your picture to 256x192 dots (or the same proportions).
2/ Convert this picture to 32,768 colors with dithering. (optional)
3/ Convert this picture to DS format with 'grit'.
4/ Remane the file extension (.img.bin to .bin).
You can convert multiple pictures at once with grit if you create the following text file:
-W3
# disable alpha and set opaque bit for all pixels
-gT!
# use lz77 compression -gzl
-gzl
# 16 bit bitmap
-gB16
-m!
#bin output file
-ftb
-fh!
This file should be named 'default.grit' and placed in the same folder as your pictures.
If devkitARM is not installed on your computer, use the 'cd' command line to select the working folder of grit. (As for me I put grit in the folder that contains the pictures.)