Uncompressed RAW File Sizes for Stills (Sony a7iii)

[hooty]

I am using the Sony a7iii and it appears that uncompressed RAW for stills is 14-bit. However, the specs show that the uncompressed raw for 16:9 resolution is 14-bit but doesn't mention bit depth in the 3:2 which I will use. Should I assume that the 3:2 ratio is also 14-bit? If so, then my main question is this...

If the RAW file is 14-bit depth at 24 megapixels, then is the correct calculation:

• 24,240,576 pixels X 14 bits = 339,368,064 bits

• 339,368,064 bits / 8 = 42,421,008 bytes

The file sizes I am getting in the .arw are about 49,668,000 bytes so I was curious what is the overhead in this RAW file? Why is it 7,000,000 bytes more than this calculation?

[Cameratose]

It is 14-bit @ 3:2. As for the rest, no idea. Not sure why it matters? What is it you're trying to determine?

 

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[hooty]

Good to know it's 14-bit. The page I found only shows 14-bit for the 16:9 ratio and not 3:2 which was the only reason it was a question. https://www.sony.com/electronics/support/e-mount-body-ilce-7-series/ilce-7m3/specifications

As for the other stuff, the reason I ask is because I'd like a decent understanding of what I'm working with. I know it doesn't matter to most people but I have a personal curiosity about it. I am trying to understand more about what a RAW file actually is, how it got there (because of the amount of pixels on the sensor and each pixel's bit depth) and then from that RAW file, understanding that a piece of software would have to triple this size when it interpolates the RAW bytes. 

I've been reading all week and I think I have my answer but just wanted it clarified here.

[FunWithCameras]

First off, uncompressed 14 bit data is not stored packed together - each 14 bit sample is stored in 2 bytes (16 bits).

Also, bear in mind that a RAW data file has more samples than there are pixels in the finished image - you need samples beyond the edges to be able to interpolate full colour information for the pixels on the edges. 

And yes, it's 14 bit data for the full 3:2 image.

The ARW file holds more than the RAW data, too - it holds metadata about the image, and it holds a JPEG that can be used to show a thumbnail.