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[filmscanners] Re: TIFF file sizes



On 4/26/02 5:08 AM, "Simon Lamb" <simon@sclamb.com> wrote:

> My mind has gone to mush and I cannot work out the following:
> 
> I scan a 6X6 frame at 4000ppi and select 48-bit output in Silverfast.  I
> assume the file size will be:
> 
> (((2.25x4000)x(2.25x4000))x3)/1024 = 237Mb
> 
> However, I am getting a file size of 406Mb.  Where is my calculation wrong?


Simon.

Nothing wrong with your math except it is for 8 bits per channel. 8 bits = 1
byte so the total pixels in and 8 bit/channel file (8 bits/pixel) x channels
is the size in bytes. However, 48 bit output is 16 bits per channel or 2
bytes (2 bytes/pixel for each channel). For 16 bit multiply by 2 (237 x 2 =
468 MB in your example). 406 is probably the file saved to disk with
compression - the disk storage size will not match the file size in RAM
except by coincidence. By the way thats MB not Mb, megabytes vs megabits.
 
Wayne

-- 
Wayne Simpkins
The Univ of Memphis
Dept of Art

hsimpkns@memphis.edu

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