Let me give you my perspective as an engineer. And this is an engineering question, not an IT question. Note that this is how I would design it, not knowing the actual requirements that TSA set.
Originally Posted by
Sydneysider
* We already know TSA was lying about the machines not being able to store or send data
* You can't create an image without some sort of file being created, right? Even when I open a pdf email attachment there is a file created (Temporary Internet Files for Windows users). When Comrade Janet talks about "erasing" the image - you can't erase something that doesn't exist. So a file IS created. How is it being erased? Just trashed/recycled or actually over-written?
Of course it can save/store images. From a development perspective, this is a necessity. That doesn't mean this feature will be available or accessible to TSO's, or anyone else who doesn't have access to the device's "engineering mode" for that matter. I would be very surprised if there wasn't some sort of persistent memory like flash or a standard hard-disk, both to store code and to store debug information like test images.
You assume however that it is based on a modern PC operating system like Windows or Linux. This isn't necessarily the case. Many devices like this are based on "embedded" operating systems like VXWorks or QNX. Regardless of OS choice, writing to disk is inefficient. Windows only does that because it has to share the file between applications. Most likely on these devices, the image is only stored in volatile memory - RAM. Anything in RAM doesn't stick around. Once it's deleted, it's gone. I would be VERY surprised if the machines, as delivered to TSA, store the images to disk. Even if it does run Windows, it's probably one application that does all of the processing. Again, no need to store to disk.
* What is the storage capability on these machines? Is it so small that every new image over-writes that last one? Or enough to hold a day's, week's or month's worth of images?
There's no way to tell. It's probably tailored to customer requirements. A customer like TSA who does not store images probably has minimal persistent memory. Other customers who do store images will have larger storage needs. Like I said though, since the images are most likely stored in RAM and not disk, there would be no way to recover them once they are no longer displayed, unless the user has some sort of "save to disk" functionality. As incompetent as I think TSA is, I doubt they are lying when they say that TSO's cannot do this.
* Who has access and control over retrieving these images?
If the device is designed (as TSA states) to not store these images, the only people who can make would be the engineers who built it or anyone else who the device maker grants access to. And again, it would have to save them to disk, which I would say is unlikely.
Like I said, I'm assuming that the TSA specified in their requirements that the images would not be stored (as they state) and that the engineers at the manufacturers like L3 are halfway competent.