Unable to open "unsupported" JPG/batch converter from jpg to another type?

[Hunter-AP]

I'm planning on hacking some models from the Fallout New Vegas Nexus, but whenever I try to open the accompanied JPG texture files in either paint or VTF Edit, I am told that the JPG is an "unsupported bitmap". What I've been doing so far is to use the DX Tex tool and export each file as a DDS, but that'll take an extremely long time that could definitely be shortened. Any ideas?