>>942099440
Too thick.
Let me post you a guide from when I used to do Xray threads (I'm the guy with the Jen efforts, above)
For reference, swimsuits are made of material that won't go transparent when wet, so it stops light - so swimsuits won't work. Anything with a bra under it won't work. Similarly lace or heavily patterned or ribbed/textured fabrics won't work well because of different transmissibility and levels. Skin-coloured fabrics are tricky for Gimp as it can't differentiate between skin and fabric. Ideally the fabric should be thin and in contact with the body. Black-and-white images are unlikely to be successful as there are no colour levels to manipulate in Gimp, just shades of grey which won't work. Similarly, colours which are totally saturated won't allow Gimp to manipulate the tones, but some of you may not be able to tell this - I'll cut you some slack in this case.
If the image is small and full of jpeg artifacts or has already been digitally processed then the results will probably be shit. As a test, zoom in on the picture and if it breaks into blocks then forget it.