Poser automatically converts TIF, JPG and BMP files to BUM format for use in the bump map texture section of the Surface Materials window. They have no purpose outside of Poser. I have a graphics viewer that will open them but the image is unclear and uneditable. When I need to make bump maps I do so in TIF format and let Poser convert them. LOL .... err little old ladies? .... loads of lucre ....lots of love ... or just possibly laughing out loud LOL :)