I'm in the process of scanning my entire offline backup of Q General for JPEGs with the criteria described by another anon on the SS Password thread.
I haven't validated the output yet. But about 3 dozen images are suspect.
An anon noticed that JPEGs created with PixelKnot start with a specific set of bytes. So my first pass is to find all of those. The bytes are,
'0xff 0xd8 0xff 0xdb 0x00 0x84 '
We are not quite sure how reliable this test. So this isn't anything to get too excited about yet.