Open the picture you want to the scene preview out of
Select an area that is 144 by 81
Copy the selection (edit>copy, or ctrl-c)
Close the image, and paste as new image(edit>paste>as new image, or ctrl-v)
Now, goto colours-> load palette..
Select the PSP palette in your 3dmm picture/palette directory. make sure list files
of type is set to
PAL-JASC palette, and error diffusion is selected.
Click ok.
Now, click File->Save as and set the file type to BMP, and the file sub-format
to
Windows RGB encoded.
Click ok to save the image.
There, now go back to the main Doc.