Thanks for mentioning this! I just remembered that I learned it from “Rosemary & Thyme” The Gongoozlers (TV Episode 2004). Fun mystery series that I highly recommend.
I had the image in Post Body originally, so it just showed text without a thumbnail. I edited it to have the image in Post URL instead, looks like that works.
I opened an old point and shoot camera and removed the IR filter in the early 2000s but it seems to have caused autofocus problems. Purple images are unedited, converted to b&w with slight contrast adjustment.