[paulycy]

Pdf docs usually do have layers. They aren’t static images like. Jpg files. Look up OCR- optical character recognition. Acrobat pulls out the text and adds it on a separate layer so it can be searchable. I’ll post more on it when im not on my phone.

Your points are well taken. However:

1) When opened in other pdf editors these layers do not appear. The pdf appears as one single image.

2)If the text were to be searchable text it would be consistent text in one electronic font and would not be a combination of dark and light (edited) characters as shown in the examples. This is more editing at the pixel level and NOT at the character level. There is editing on the signatures also and they would NOT be OCRed.

So I don't think the OCR layer theory holds up under this evidence.

[mike182d]

Furthermore, when working in Illustrator, and specifically commercial print, there is a difference in the appearance of 100K black (CYMK) and "Rich Black."

It's quite possible that if the original was scanned and modified, the color settings in the program/computer they were using made the modified text appear on their screen as the same color when in actuality it was a lighter/darker shade and would appear as such on other machines.