Dash Cam footage is it safe.

[ericmark]

My hobby is photography, much of it involves the use of photoshop likely every image goes through photoshop simply because I take RAW images which are 12 or 14 bit and they need reducing to 8 bit to display.

I watched this BBC report and most of the footage is likely unaltered, however the voice over refers to numerous witnesses reporting some one was driving too fast and jumped a red light, but he got off with it because the web cam showed the light was green, I don't think I would have any problem changing the colour of a traffic light.

I have not found a way to alter RAW images, but every other image is altered to some extent by the camera, even if not out of the camera, dash cam.

It does say

Footage has to be unedited and include the whole journey, not just the incident. Members of the public are also told not to post it on social media, or to remove it if it has already been posted.

however it also said that with the exams I took, but students were allowed to take Jpeg images into the exam, and Jpeg are always altered from original.

 

[Lucid]

You could change the colour of the light, but green is at the bottom and red at the top, so there'd be quite a lot of editing to do to successfully erase a red light from all the footage that contained it and also change the traffic pattern too. The sequence of the lights: Red > Red + Amber > Green > Amber > Red

Eye witness reports are notoriously unreliable. It wouldn't surprise me if the camera and the eye witness reports conflict. There's lots of reasons for this including angle of view, prejudice, emotional state; but the biggest single factor is the way recall works. This may help explain how people can fool a lie detector machine. They convince themselves that their version is right.

Cameras don't tell the whole story either. For example, its harder to judge distance with a flat 2D image.

JPEGs: They're resampled every time the file is saved. So yes, they're different from the original. I guess that then becomes a question of acceptability for the exam board?

 

[ChrisR]

Sure you can alter RAW images, there are hacks "out there". It's only numbers in memory. The simple ones let you alter the exif.
Wildlife Photographer Of The Year judges tried to rely on seeing the raw file as evidence - oops.

Dashcam footage is just relatively crappy video though, isn't it? I've sat in with the video editor where they did the Citroen -Robot TV commercial. Impressive abilities, they'd have no problem changing a traffic light colour. Expensive software though. I expect forensic analysis would show it up, but plod wouldn't bother over a 3 pointer. If you re-shot the scene with the required light timing vs car position, that would make it quite easy - "clone in" the light with similarly angled footage. Business opportunity there...

Did you ever see the Top Gear footage with the mad three tearing around the USA, with the speedo drifting between 50 and 55mph?
As a side issue, whenever I've seen dashcam footage as evidence, I've always noticed how much better it would have been if there had been two dashcams, one each side. Wider field, and stereo in the middle, just like us!


"Jpeg are always altered from original." Often a camera only spits out Jpeg though. What exam?

 

[ericmark]

I did the 'A' level art exam in digital photography, for the exam the student was required to take a number of unaltered and untested images into the exam and process them in the exam and print. As to why for a "digital" photography they had to be printed I don't know, I would have expected a PDI to be the final, but that was the rules.

I am sure everyone did test the images before the exam, and there was no way anyone could show if tested or not. But as far as unaltered then using RAW would mean in the main unaltered.

I will admit I here the phrase "straight out of the camera" so many times, but with both my DSLR cameras there is a far bit of manual post exposure manipulation which can be done to convert the RAW into Jpeg inside the camera, some mobile phones will allow even more swapping heads around warping etc. In the main easier to do on the PC but does not need to be.

In the case of an accident where the police collect the dash cam at the scene then no real worries, but once they allow that footage to go to some ones home, then it means you can fiddle with it, and if some one wishes to spend the time they can do all sorts.

It is correct that with wild life photography there are some very strict rules, these are being questioned, as judges recognise scenes where it is known wild life is not really wild any more. Watch the program "Wild at Heart" and you see how game reserve and sanctuary's have animals introduced it may be 1500 acre but in essence no different to Longleat and Longleat is not that different to Chester Zoo. The animals are not truly wild, and the question is asked time and time again about grooming wild animals, I do it myself, I have a bird table where I feed birds, so I can take pictures of birds around the table which are technically wild, but have been groomed, this has grown in some areas to big business with hides provided to the photographer and streams and rivers stocked to encourage the king fisher for example.

Photography has been changed and manipulated for years, this is why an original Ansel Adams print is worth so much, it was his skill dodging and burning as much as the original image which made them so good. At $722,500 for a print, not even the original negative one can afford to spend a lot of time getting it right.

A dash cam takes a load of still pictures which the human eye sees as moving, yes because so many pictures it takes more time to alter them, but it is down to how much it is worth to some one to either get some one's licence revoked or to keep one's licence as to how much one is willing to pay, or do to alter what is shown. Where the footage comes from a traffic camera OK, but from a personal web cam then very different.

 

[ChrisR]

I'd have expected you'd have to use a colormunki or similar for A level, for printing?
I did some lectures recently, it was hard to get Colour Space and calibration across.

Yes the old printers used to put far more work into processing than pressing the button, I find it hard to understand why some people are doctrinal about "getting it right in the camera". Just dumb, I guesss .

 

[ericmark]

We have a colormunki at the camera club, but at collage did not see one, we were told the one computer the high quality printer was attached to was calibrated, however this was a major problem, it takes around 6 minutes to print a 12 x 10 print, each student has to print 4 that is if non are scrapped, so each student needs at least 24 minutes at the master computer used to print the pictures in real terms over 1/2 hour each, the exam is 12 hours long so 16 students need between them 8 hours for printing, which is clearly nearly the last thing to do, after that they need mounting so unless the lecturer tells students to do one image at a time you have that 12 hours roughly split into 3 sections, first process images, second print images and last mount them. So even allowing for some being faster than others, if all students start together you have a queue waiting for printer.

The exam is spread over I think 5 days, in real terms each student has three days, so by staggering the times it can be arranged for students to have varying finish times, but that means the lecturer has to be in the exam room for all of the 5 days, since there will be other lecturers the students will also have to have some times when they can't attend the exam.

As to get it right in the camera that has not really changed, one camera is 12 bit the other is 14 bit, but that is not enough to capture the whole dynamic range for some scenes, so the neutral density filter is still required, or you need to take 3 or 5 images at 2 EV stops apart to get it all. And multi images are not much good if things are moving. I will often set the camera to plus and minus 2 EV but only use one image.

 

[Tarbyonline]

Would the editing program not leave a trace in the file data in any case? A number of years ago I had a look at the code of a word processor document and was amazed to see not only a date and time stamp for every single time the file had been re-saved but also every time it had been printed! Theoretically anything can be altered given enough time/perseverance/skill/money and the resulting traces hidden (I'm sure the likes of the secret services are particularly good at this!) - high end software can now theoretically clone someone's voice to create audio as if they actually said something that hasn't been for instance. Some insurers now specify that for dashcam footage to be accepted it must be from one of a number of particular models. These normally stamp the date and time as well as having a running counter stamped into the footage to make them much harder to edit.

RAW files could be altered - at the end of the day it is just the data taken directly from the sensors expressed as 1's and 0's. It's just a matter of cloning the codec used in the camera - essentially it the reverse process of what the likes of Lightroom does to Change the data into a visual image. Submitting an unedited raw file is basically submitting a negative in film terms, and not even those are totally impossible to falsify (though admittedly extremely difficult and able to be picked up by a trained eye).

 

[ericmark]

My dash cam does clearly have meta data giving date and time, however nothing on the picture its self, it is extreme wide angle and tends to make it seem that there are 100's of near misses in a trip due to the wide angle. It is set to one frame per second most of the time, so trips shown in fast motion, which suits me as it's there to capture scenery so I can extract the still pictures latter. It would have cost me more than the £35 spent to buy a lens for my DSLR that wide, in still mode it takes at 12 Mp and gives better quality pictures than the lens converter I have been using on my 18 - 55 mm lens used with the DSLR so it does what I want, only down side is it defaults to movie mode when switched off.

The fact I did not get it to record traffic does not mean others don't use the same camera to do that job, and at the scene of an accident Police collecting dash cam cameras is a really good idea, if there is simply a time limit imposed for submitting footage it would reduce the ability to alter footage without it being detected, but it worries me that police are asking for footage of near misses and one wonders what people may submit when they are annoyed by some one even when the real crime was not traffic related. The I will get my own back attitude, and alter footage to show some one running a red light.