32mg per image in Raw on XE-2?

Started Feb 20, 2014 | Questions thread
nixda Veteran Member • Posts: 5,515
Re: Back of the envelope

Perry Kivolowitz wrote:

nixda wrote:

Perry Kivolowitz wrote:

nixda wrote:

Perry Kivolowitz wrote:

I was surprised as well as it is getting close to the D800 raw files when shot with full compression at 12 bit.

Fuji doesn't appear to use any compression for its raw files.

Plus no option to downscale to 12-bit files on output.

4896*3246 * 3 channels * 2 bytes per channel = 95,883,264 > 32MB

The raw data image size is 5120*3288*14 bits = 28.1MB

There aren't 3 channels per pixel, just one. Add to that the JPEG thumbnail, the metadata and some other stuff, and you'll end up with the ~32MB file size.

Ah (as in Doh!). I should have known that.

But, it is unlikely that 14 bits are written as 14. Rather as 16, making the file requirements marginally larger.

Any number of bits can be written. They don't have to be 8, 16 or 32, i.e., 1, 2 or 4 bytes. Normally, to keep files as smalls possible, no empty bits are written. Only when loading the data into a processing program are they converted to 8, 16, or 32 bit formats for the subsequent mathematical operations. In other words, there is a difference between storing data and performing operations on them. One can also define operations in any bit space, but that's usually only done when space is of the utmost premium.

I'm not sure I agree with you that 14 bit data is "normally" written in a packed format.

I don't think they are packed data, just plain 12 or 14 bits resp., depending on whether we are talking about the X-E1 or the X-E2.

Let's take the X-E1, for example. It has the same number of pixels as the X-E2, yet the file size of a raw image is much smaller than that of the X-E2. If the data were both written in 16-bit format, the files would be roughly the same size. The X-E1 files (~26MB) clearly are too small to contain 16-bit data, not even 14-bit data. Here, 5120*3288*12 bits = 24.1MB, which is already close to the file size.

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