Smaller BMP files in Subrip. Is it possible?

[Danvil]

I would like to know if there is a way to compress the bmp's and use them in DVDMaestro.
I extracted the subtitles of "Hunt for the Red October" and the BMP's total size was almost 200 Mb.
If I use Maestro to convert a SSA file to BMP's the total BMP size is just about 10 Mb.
Is there a way to compress the BMP's that SubRip creates?

[oddyseus]

use a batch file in Photoshop to change the format of the bmps to index color and check if they work.

The size however would go from 1.2mbs to 0.3mbs.