4 ms·

Even photo and video evidence suffers from courtrooms that don’t understand how nearly all cameras will record and encode images. JPEG encoding (and thus MPEG

Even photo and video evidence suffers from courtrooms that don’t understand how nearly all cameras will record and encode images. JPEG encoding (and thus MPEG encoding) takes 8x8 blocks of pixels and represents them as a discrete cosine transform. In a very real way these pixels don’t actually exist. If your video evidence relies on such a small portion of MPEG encoded video, you can easily mislead a jury to convicting an innocent person. I’m reminded of the Rittenhouse trial where the prosecutors had a technician massage a still from a video for hours until some very tiny collection of pixels, enlarged from the original by quite a bit, were arranged in such a way that they said demonstrated Rittenhouse initiated aggression against the first man he shot. The defense actually had some idea about such a small collection of pixels not being a reliable representation of reality, but couldn’t sufficiently explain it and didn’t have an expert who could, so the judge allowed it.

Lord-Jobo 3y ago
This is one of the better litmus tests to see if the expert witness is knowledgeable in the field, and more importantly, up-to-date on the tech. some really smart but definitely older expert witnesses will fumble this very hard. Its not like those kinds of processes, the "enhancing" filters, are inherently bad or inadmissible, you just have to be clear with the judge and jury what the hell is actually happening.
- gjsman-1000 3y ago
  This also came up in the Johnny Depp trial, where evidence was challenged and there was a long discussion about whether a video that had been shared over AirDrop was admissible, or whether that should be considered tampering, due to the possibility of it being re-encoded / compressed (which is a theoretically possible concern, as doesn't iPhone record in HEVC but change it to H.264 when shared with people?)
- thfuran 3y ago
  >This is one of the better litmus tests to see if the expert witness is knowledgeable in the field, and more importantly, up-to-date on the tech It's an absolute travesty that it should fall to expert witnesses at all. Judges, police, and criminal trial lawyers should know how common forms of evidence work in general.
  - Lord-Jobo 3y ago
    In my experience its just that technological ignorance muddies things so much that smart judges who otherwise understand evidence and admittance well will be silent when they arent sure, or worse, get actively bamboozled by shitters.
- brigade 3y ago
  And conversely, it's a good litmus whether to listen to the "experts" on websites like this one. So many would discount literally any image/video evidence just because of JBIG2's pattern matching or Samsung's ML model of the moon, without bothering to think about what's actually happening in the relevant pipeline.
gruez 3y ago
>I’m reminded of the Rittenhouse trial where the prosecutors had a technician massage a still from a video for hours until some very tiny collection of pixels, enlarged from the original by quite a bit, were arranged in such a way that they said demonstrated Rittenhouse initiated aggression against the first man he shot. Is there an article with more on this?
- rpmisms 3y ago
  Didn't find any with a cursory search, but the full trial is available on YouTube, and this particular argument is incredibly frustrating to watch. The judge should never have allowed it in.
- adamsb6 3y ago
  Not terribly in depth, but this is about the evidence I referenced: https://apnews.com/article/kyle-rittenhouse-technology-wisconsin-kenosha-homicide-b561bef68dc6aadaadc9b45a1bd93a19 https://apnews.com/article/kyle-rittenhouse-technology-wisco... IMHO any upscaling in court should be strictly squaring existing pixels, along with heavy caveats on how encoding works. A 16X zoom means one black pixel becomes sixteen pixels, and jurors have to know that the individual pixel may not have ever been an accurate representation of reality. Anything else, even nearest neighbor, is adding information. Especially with recent smart phones that are using AI to perform “super zoom” techniques you could easily magic into existence something that never existed.
- Ukv 3y ago
  This is the "clarified" video frame in question, alleged to show Rittenhouse aiming his rifle at protesters: https://i.imgur.com/7uWonoK.png https://i.imgur.com/7uWonoK.png (unfortunately with some extra degradation due it it being a screenshot from the trial footage) The glob of pixels to the left, interpreted as Rittenhouse's support hand, was actually part of the vehicle already present in the frames before he approaches: https://i.imgur.com/4itI2r8.png https://i.imgur.com/4itI2r8.png

Lord-Jobo 3y ago

This is one of the better litmus tests to see if the expert witness is knowledgeable in the field, and more importantly, up-to-date on the tech. some really smart but definitely older expert witnesses will fumble this very hard. Its not like those kinds of processes, the "enhancing" filters, are inherently bad or inadmissible, you just have to be clear with the judge and jury what the hell is actually happening.

gjsman-1000 3y ago
This also came up in the Johnny Depp trial, where evidence was challenged and there was a long discussion about whether a video that had been shared over AirDrop was admissible, or whether that should be considered tampering, due to the possibility of it being re-encoded / compressed (which is a theoretically possible concern, as doesn't iPhone record in HEVC but change it to H.264 when shared with people?)
thfuran 3y ago
>This is one of the better litmus tests to see if the expert witness is knowledgeable in the field, and more importantly, up-to-date on the tech It's an absolute travesty that it should fall to expert witnesses at all. Judges, police, and criminal trial lawyers should know how common forms of evidence work in general.
- Lord-Jobo 3y ago
  In my experience its just that technological ignorance muddies things so much that smart judges who otherwise understand evidence and admittance well will be silent when they arent sure, or worse, get actively bamboozled by shitters.
brigade 3y ago
And conversely, it's a good litmus whether to listen to the "experts" on websites like this one. So many would discount literally any image/video evidence just because of JBIG2's pattern matching or Samsung's ML model of the moon, without bothering to think about what's actually happening in the relevant pipeline.

gruez 3y ago

>I’m reminded of the Rittenhouse trial where the prosecutors had a technician massage a still from a video for hours until some very tiny collection of pixels, enlarged from the original by quite a bit, were arranged in such a way that they said demonstrated Rittenhouse initiated aggression against the first man he shot. Is there an article with more on this?

rpmisms 3y ago
Didn't find any with a cursory search, but the full trial is available on YouTube, and this particular argument is incredibly frustrating to watch. The judge should never have allowed it in.
adamsb6 3y ago
Not terribly in depth, but this is about the evidence I referenced: https://apnews.com/article/kyle-rittenhouse-technology-wisconsin-kenosha-homicide-b561bef68dc6aadaadc9b45a1bd93a19 https://apnews.com/article/kyle-rittenhouse-technology-wisco... IMHO any upscaling in court should be strictly squaring existing pixels, along with heavy caveats on how encoding works. A 16X zoom means one black pixel becomes sixteen pixels, and jurors have to know that the individual pixel may not have ever been an accurate representation of reality. Anything else, even nearest neighbor, is adding information. Especially with recent smart phones that are using AI to perform “super zoom” techniques you could easily magic into existence something that never existed.
Ukv 3y ago
This is the "clarified" video frame in question, alleged to show Rittenhouse aiming his rifle at protesters: https://i.imgur.com/7uWonoK.png https://i.imgur.com/7uWonoK.png (unfortunately with some extra degradation due it it being a screenshot from the trial footage) The glob of pixels to the left, interpreted as Rittenhouse's support hand, was actually part of the vehicle already present in the frames before he approaches: https://i.imgur.com/4itI2r8.png https://i.imgur.com/4itI2r8.png