That is not the URL of an image, but to the forum script that stores attachment info. You need to get the URL of the image itself:
http://www.shrapnelcommunity.com/thr...ubothak_FF.bmp
For reference, it is better to upload PNGs or something than bitmaps. Most apps let you save as PNG already, and there is no color loss with PNG (other than 8-bit PNGs, ofc).