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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?


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 Simpkins
The Univ of Memphis
Dept of Art


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