From the FreeRepublic we receive some good feedback from a poster named Butterdezilion.
Butterdezilion: If the Xerox machine is substituting exact replicas every time a certain “blob” (such as a box) appears, then that should happen with every box, every letter, etc. If the Xerox is switching 6’s for 8’s then where are those numbers switched around in the White House PDF?
A good question but as I have shown and found out, the Mixed Raster Compression is all but exact as it appears to be extremely sensitive to small variations. I have seen examples with anywhere from 4 to 17 foreground images. The same for JBIG2, it is based on how similar the two blobs, such as a box are, and in the samples I have, I have found JBIG2 to fail to capture the boxes, but it does capture other letters.
Butterdezilion If NBC scanned in the White House document which is a print-out of a document that ALREADY had these effects within it, then the real test would be whether the scan he comes up with is DIFFERENT than the White House PDF, not whether it is the same.
Exactly, it is not perfectly the same, or otherwise there would be reasons to doubt my findings. But the scan shows evidence of all the artifacts I mentioned, other than the halo effect which was of course already present in my ‘original’
Butterdezilion: If scanning the White House document using the Xerox machine under these conditions results in a PDF that hasn’t been manipulated by the Xerox (different than the document that was scanned in), it would actually CONTRADICT the theory that the Xerox made the anomalies in the actual content of the White House image.
The Xerox scanner does not ‘know’ that the document it scans used to have layers in it, and therefor it reproduces as best as it can the Mixed Raster Compression it is instructed to use by the default workflow. This results in similar but not perfect matches.
Even having access to the original Long Form Birth Certificate would not fully replicate the PDF provided by the WH, however I have now shown that the following features are captured
- Separation into a jpeg background and multiple monochrome foregrounds
- Alignment of two boundaries with 8×8 bit offsets
- Alignment of two boundaries with internal object
- Downsampling the background to 150 DPI
- Downsampling the foregrounds to 300 DPI
- Saving the JPEG with a quality factor of 47.48% with specific Quantization Matrix
- Embedding a YCbCr comment into the generated JPEG
- JBIG2 compression
- Preview created clipping mask
- Images are all in landscape direction requiring 90 degree ccw rotations
- The JPEG contains the same JPEG comment YCbCr
- The JPEG contains the same quantization matrix
- Full or almost full separation of the date and signature stamp
- Speckled foreground bitmap
What I have yet to explain includes:
Halos Although I believe the workflow provides us with plenty of hints there and preliminary experiments are looking promising. It’s just that I am working through the list somewhat methodically, often repeating experiments based on the feedback from others like RC, Goregan, Vicklund and our friend Hermitian.
Is that it? Just the Halos? Did I miss something? Surely there are more artifacts that were claimed to be evidence of a forgery and which can be explained through the workflow I propose?