Do you want to have a .bum extention or just make a Jpeg into a bump map....If you have Poser 4 that will convert jpegs into .bum....But if you want a bump.jpeg...for poser pro and up....well first of course load your jpeg then go to IMAGE-MODE-GRAYSCALE then go to IMAGE-ADJUSTMENTS-BRIGHTNESS/CONTRAST then adjust Contrast between +38 to +42 then go to IMAGE-ADJUSTMENTS-INVERT and that's it, now your jpeg is a bump map you can use in poser:)