Where Did The Bits Go ?

[Marc Hildebrant]

Group,

I have a Canon EOS 90D camera and I am trying to understand how many bits are used to represent each pixel.

The Canon web site states that the camera, in RAW mode, has a sensor that is 6960 X 4640 Pixels. This equals about 32 Millon pixels.
The IMAGE Format states that RAW is "14 Bit Canon Original". The Raw file is 35.6 Mbytes.

I do not understand the raw file size number.

A Byte is 8-bits. 6960 X 4640 Pixels is 32,294,400 actual pixels. If each pixel is represented by 14 bits, then that would be 452,121,600 total bits.
Digital words use 8-bit bytes, and 14 bits is usually stored with two bytes which allows for 2 bits to be always 0 (16-bit word length).

Maybe Canon uses a unique bit length, but I do not understand how a raw file can be 35.6 Mbytes when you need to store 452,121,600 toral bits.

452,121,600 divided by 8 equals 56,515,200 Mbytes not 35.6 Mbytes.

Maybe the Canon phrase "14 Bit Canon Original" has a special meaning?

I know that Canon offers a compressed raw file, but this is not what I am referring to.

Comments?

Marc

 

[Original katomi]

Yea.
Whooosh right over the top of my head…. Only understand one word.
Canon lol

 

[RVT1K]

I'm not sure there is a relationship to the total file size and the 14-bit dynamic range.

And while "14 Bit Canon Original" probably has more to do with marketing, a bit is a bit.

And it is very likely that the data buss is far wider than 14-bits and only a portion is used for the imaging information.

My last job was as a senior tech for a company that made tools used in the semiconductor industry -specifically electron lithography machines. We advertised 18-bit resolution but the data buss was far wider, more like 64 bits to carry lots more info like memory addresses, corrections and a whole host of data and address strobes.