Bryce converts *all jpegs* back into full color tiff/bitmap which are even larger than original bmps because they also store math and file calculations when saved as *.mat.
You can sometimes reduce the mat file size by using full color bitmaps instead of importing jpgs!
I've mentioned this several times and nobody wants to believe me (boo hoo eh?)...
I tested it a hundred times with several members - results are always the same.
* Don't bother converting to jpeg if you're going to save as Bryce mat *
Last time I did this to illustrate to another the size difference was 900k.
It will still be large. Again - it isn't you. It's Bryce doing it behind your back.
The exported mat file size is also dependent on how much color there is in the original image so shown below are some results to compare.
[I would not recommend converting bitmap to jpeg if the pict texture is for your own use]
If you use a seperate Alpha (Middle Picture) channel for bump/transparency this will add to file size.
I was just experimenting again and have four Bryce mats (756x512 pixels)
#1 Top made with jpg (original weight=180k) Pic textures in Channel A. (Alpha was converted to grayscale)
1) Size is now 1,283kb - looks ok, ho hum...
#2 Middle was made with same pic as bitmap 1.11 meg - conversion to gray for alpha also
2) Size is 1,556 kb but looks ten times better! I'll take it for the measly 273k difference.
#3 bottom was made with color bmp and grayscale bmp + 2 procedural mats
3) Size is 1,579 kb and looks crummy - the "extra" file weight is from the procedural mats of course.
The Bryce mats washed out the neato teeth.