The funny thing is when I painted a painting from my picture a couple of months ago I missed the button too. The micro-scan we did in SLC at Borg Anderson Photography yielded much more information about the picture such as a button we had not seen before. Here is the interesting part; the Library of Congress image shows the suggestion of the button or buttons. As I have always contended it is an edited version of my Joseph Smith photo and not an edited version of the painting.
Another neat finding came about a couple of days ago as I was looking at the image in Photoshop. I had this feeling that I was just missing something, that there was more, more I could use to prove this was a real photograph. I was playing with the contrast and multiplying the image over its self to enhance what information was already present but not visual to the human eye. Suddenly, it was a WOW moment! What I noted was an "S" over the knot of his cravat. I multiplied it further to enhance the image, and there it was. What I think it could be is a monogrammed locket with an "S", or it could possibly be a tie pin, but it seems a bit large for that. I also see suggestions of a chain possible. Furthermore, I might add that the Community Church of Christ's painting does not have anything like this on it. I did read that Emma had a locket of Joseph's hair she wore, which was passed onto her daughter Julia. Is it possible Emma originally gave Joseph the locket, and he was photographed with it?
Note: In the photo, I superimposed a monogrammed gold "S" below it as an example, it doesn't appear to be the exact font but is similar in design.