Just for fun, I’ve been Polariking1 Donald Trump’s City of New York birth certificate. What I was primarily looking for was a raised seal, and that wasn’t anywhere to be seen. However, when I adjusted levels, I did see that the bottom part of the form was in two very distinct colors, which I can’t readily explain. That image follows:
Here is the unretouched image extracted from the PDF:
And here is the image with the negative section inverted and lightened.
What appears in the upper left seems to be a rubber stamp. I can’t be sure but it looks like:
BUREAU OF RECORDS DEPARTMENT OF HEALTH BOROUGH OF QUEENS
1Polariking: Looking at images at high magnification and imagining things that aren’t there.