Maybe it’s just one frame per file? Also, you could probably achieve some pretty good compression with multiple frames because the frames are probably very correlated, right?
So if it's one Raw sensor frame, it will be noisy, and you won't get any of the computational photography benefits. It will end up looking like a photo from a 10 year old phone.
You will get a little compression storing multiple frames, but not much, because the photon shot noise is independent for each frame - and in lossless images, the noise (which does not compress according to information theory) often has more entropy than the ideal image (which compresses well).
Or you could store one post-processed frame, after you have combined 128 frames and done the computational photography stuff. But at that point, it isn't exactly raw data anymore.
> noise (which does not compress according to information theory)
That's true in theory/isolation, but in practice we know the noise has much lower maximum amplitude than the original image. I.e. if you take a difference between two frames, almost all of it will require less bits per pixel than the signal. (And that allows compression in practice)
"So if it's one Raw sensor frame, it will be noisy,"
That is not why noise is created in digital photographs. And Noise or Grain in a photograph is not always a negative.
"Noise in photography is the arbitrary alteration of brightness and color in an image. The onset of this random variation generates what is called “noise”or “grain”, which is basically formed by irregular pixels misrepresenting the luminance and tonality of the photograph. These pixels are visible to the eye due to their large size."
A signal RAW image does not have to have noise. Noise can be created by incorrect exposure and low light.
>Or you could store one post-processed frame, after you have combined 128 frames and done the computational photography stuff. But at that point, it isn't exactly raw data anymore.
Yes, and Apple should not be calling any images it captures from an iPhone "RAW".
> A signal RAW image does not have to have noise. Noise can be created by incorrect exposure and low light.
You always have noise. It's more noticeable in low light, but it never goes away. It's due to physics - there's real world noise in photons hitting the sensors and read noise in the A/D converters behind them. That's long before the image is captured into any format - RAW doesn't help you here.
There is always noise. In fact, in absolute terms, there is more of it as the amount of light increases. It just increases more slowly than the signal, so the signal-to-noise ratio increases.
> Are there any cameras out there that output real raw data from the senors?
I suspect not, because the data output rate from a high end sensor can easily be 32 Gbps, and I don't think any phones have fast enough flash storage to write data at 32Gbps.
You have to process the data in mostly-realtime or lose the data. Storing it isn't an option.
Full sized cameras do use a buffer to deal with burst activity, take series if shots - process - save to slower storage. Also, modern cameras start switching to CFexpress/SDExpress (which are NVMe)
> Version 8.0 was announced on 19 May 2020, with support for two PCIe lanes with an additional row of contacts and PCIe 4.0 transfer rates, for a maximum bandwidth of 3,938 MB/s
Full-sized mirror/mirrorless cameras do that. Sensor is HUGE, optics is very fine and huge as well. Due to how universe works, you can't get similar results with tiny sensor and optics
