hehe Lossless means when you take a image and compress the heck out of it. A uncompressed image might be a BMP or a Tiff or a any number of formats. JPG can be highly compressed or just a little bit. The more you compress it to make a smaller file size the more the colors and image blend. Think of it as a viewable ZIP file. A BUM file is a BMP uncompressed and can be pretty big size wise. But converted to a jpg its pretty small but you pay a price for it in clarity. In poser you conver it to a jpg but come render time it has to uncompress it in order to use it and this takes up allot of resources as far as i can tell. UV mapper will tile a texture for you across the mesh. What exactly are you tring to texture ?