As I found ou on http://www.imagemagick.org/Usage/formats/#bmp the conversion can be done using $ convert blop.jpg ppm:- | convert - BMP3:image.bpm
Now cuneiform takes the BMP file. But I guess that's not an usual workaround a normal user who just wants to OCR a few documents will try... So the problem persists.
As I found ou on http:// www.imagemagick .org/Usage/ formats/ #bmp the conversion can be done using
$ convert blop.jpg ppm:- | convert - BMP3:image.bpm
Now cuneiform takes the BMP file. But I guess that's not an usual workaround a normal user who just wants to OCR a few documents will try... So the problem persists.