re: #305 ReamWorks, SKG (fka Reuven)

I can assure you that any “white halos” in a JPEG compressed document that contain scanned text with hard edges are a result of the JPEG compression process, and not any grand conspiracy.

There’s an artifact in signal theory called “ringing” which occurs whenever there’s a low-pass filter applied to a signal. One of the key elements in JPEG compression is using fewer bits to represent higher-frequency information. This filtering results in the halos around hard edges.

[Link: en.wikipedia.org…]

This is what I do for a living, so if anyone wants the full story about JPEG compression, I can tell you. I don’t think the Birther movement can be re-invigorated, so it may be a moot point.

Indeed, I would not be surprised by such artifacts in any lossy-compression file, which I believe is typical for PDF.