# Re: Calculating Scan Size

From: Jon Danforth ^lt;jdanforth@sc.rr.com>
Date: 02/20/04-01:11:43 PM Z
Message-id: <000701c3f7e5\$611edd50\$6401a8c0@Hualon>

Sandy,

Try using the scan calculator at scantips.com. I use this all the time.

For instance, scanning a 645 negative at 2400dpi yields these results:

Input
(2.205 inches x 2400 dpi) x (1.693 inches x 2400 dpi) = 5291 x 4063 pixels
Output
(10.419 inches x 508 dpi) x (8.000 inches x 508 dpi) = 5291 x 4063 pixels

This also gives you the equation for calculating it on your own later on.
To get the size in MB, you'll have to then multiply each value by the number
of bits per channel (8 or 16) by the number of channels. Then you divide
multiply the number of bits by 8 to get the number of bytes and then divide
that number by 1024 to get the number of megabytes.

So if you have a grayscale image, that's 5291 * 8 = 42328 + 4063 * 8 = 32504
= 74832 bytes / 1024 = 73.08 MB.

RGB color is just three times that (roughly). Keep in mind that these
calculations are based on scanning at 2400dpi.

There's probably a more simple way of doing it but I'm a bit rushed right
now. The light outside is AWESOME.

-Jon

----- Original Message -----
From: "Sandy King" <sanking@clemson.edu>
Sent: Friday, February 20, 2004 1:41 PM
Subject: Calculating Scan Size

> I know there must be a fairly simple way to figure out the total size
> of a file in mb based on scan resolution and size in inches but when
> I do the calcuation the way I think it should work it never agrees
> with the size of the actual scan.
>
> So how is the calculation made?
>
> Sandy King
>
Received on Fri Feb 20 13:12:03 2004

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