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Should be noted that a)virtually nobody used the compression method in question and b)in the few examples they did, it was quickly found to be harmful, modifyin

Should be noted that a)virtually nobody used the compression method in question and b)in the few examples they did, it was quickly found to be harmful, modifying digits and letters. That compression format should have been aggressively removed once the flaws were uncovered. It presented a real-life danger on so many fronts. Imagine engineering documents, medication orders, architectural specs, you name it. That compression algorithm easily could have killed people.

misnome 4y ago
From what I remember from the kerfuffle around JBIG a few years ago, it was specifically a single manufacturers bad implementation that regularly swapped numbers. I believe that correct implementations weren't found to exhibit this problem except on symbols that were hard to read already?
- mrguyorama 4y ago
  The problem was that JBIG had multiple different option sets, including an option that was explicitly "lossy" which here means that it is apt to replace one portion of an image with another. For some unfathomable reason, Xerox set this option as the default on many of their products, instead of the lossless, nearly as well compressing option.
josefx 4y ago
> virtually nobody used the compression method in question and JBIG2 came out around 2000, when the compression issue went public in 2013 it was in widespread use by many Xerox scanners that could scan to PDF and could not be turned off. Of course as non American I have only heard that xerox is synonymous with copying so I might misinterpret the impact the issue had. > b)in the few examples they did, it was quickly found to be harmful, modifying digits and letters. If I understand it correctly the refinement encoding that was exploited in this case would have prevented the replacement issues by storing visible differences along with the glyph replacement. However Xerox did not seem to make use of this feature, resulting in the problematic changes even at the highest quality settings. > you name it. I think Obamas birth certificate was among the victims. Some of the artifacts conspiracy theorists found on available images of it may have been caused by the JBIG2 compression algorithm of a Xerox scanner.
oynqr 4y ago
Who would ever want to compress bitonal images, right?

misnome 4y ago

From what I remember from the kerfuffle around JBIG a few years ago, it was specifically a single manufacturers bad implementation that regularly swapped numbers. I believe that correct implementations weren't found to exhibit this problem except on symbols that were hard to read already?

mrguyorama 4y ago
The problem was that JBIG had multiple different option sets, including an option that was explicitly "lossy" which here means that it is apt to replace one portion of an image with another. For some unfathomable reason, Xerox set this option as the default on many of their products, instead of the lossless, nearly as well compressing option.

josefx 4y ago

> virtually nobody used the compression method in question and JBIG2 came out around 2000, when the compression issue went public in 2013 it was in widespread use by many Xerox scanners that could scan to PDF and could not be turned off. Of course as non American I have only heard that xerox is synonymous with copying so I might misinterpret the impact the issue had. > b)in the few examples they did, it was quickly found to be harmful, modifying digits and letters. If I understand it correctly the refinement encoding that was exploited in this case would have prevented the replacement issues by storing visible differences along with the glyph replacement. However Xerox did not seem to make use of this feature, resulting in the problematic changes even at the highest quality settings. > you name it. I think Obamas birth certificate was among the victims. Some of the artifacts conspiracy theorists found on available images of it may have been caused by the JBIG2 compression algorithm of a Xerox scanner.

oynqr 4y ago

Who would ever want to compress bitonal images, right?