RE: Calculating Scan Size

Sandy, Perhaps it is time for a DVD burner and move up the scale. ; )
I had a couple of frustrations with files just a bit too bit for a cd.

Eric Neilsen Photography
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Dallas, TX 75226
http://e.neilsen.home.att.net
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> -----Original Message-----
> From: Sandy King [mailto:sanking@clemson.edu]
> Sent: Friday, February 20, 2004 2:41 PM
> To: alt-photo-process-l@sask.usask.ca
> Subject: Re: Calculating Scan Size
>
> My purpose in asking the question has nothing to do with arguing
> point. I am making some scans of large 5X7 negatives and want to keep
> total file size below 700mb so I can save the raw file to a CD.
> Unfortunately the scanning software that I am using does not tell me
> the final file size after I indicate resolution and target size, as
> some software does.
>
> Sandy
>
>
>
> >Good point. I always scan into an uncompressed 16 bit TIFF so I didn't
> even
> >think about getting into compression. Mike's right because there really
> is
> >no easy way to calculate size on disk.
> >
> >Those calculations are handy when you get in a digital vs. analog
> argument
> >and someone brings up megapixels as their only arguing point. My
> response?
> >Well if you're only counting megapixels then I've got way more on a 645
> >negative than you do.
> >
> >:p
> >
> >-Jon
> >----- Original Message -----
> >From: "Mike Finley" <ekng532@f2s.com>
> >To: <alt-photo-process-l@skyway.usask.ca>
> >Sent: Friday, February 20, 2004 2:26 PM
> >Subject: Re: Calculating Scan Size
> >
> >
> >> On Fri, 20 Feb 2004 14:11:43 -0500, Jon Danforth <jdanforth@sc.rr.com>
> >> wrote:
> >>
> >> >Sandy,
> >> >
> >> >Try using the scan calculator at scantips.com. I use this all the
> time.
> >> >
> >> >http://www.scantips.com/calc.html
> >> >
> >> >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
> >> >
> >>
> >> This gives the megabytes of image data in the file, but doesn't
> >> necessarily equate to the file size on the disk, if that was what
> >> Sandy was asking about.
> >> Some formats compress heavily, and throw away data in the process, eg
> >> JPEG
> >> Some formats compress less heavily and can restore exactly the same
> >> data when opening the file.
> >> Some formats do not compress at all.
> >> Tiff files can be any of the above, depending on options chosen
> >>
> >> In addition to the image data there will be a small amount of
> >> additional data needed to identify the contents to software that is
> >> using it.
> >>
> >> So if you are talking about file sizes on disk, then there is no
> >> direct correlation to resolution and image size.
> >>
> >> mike
> >>
> >>
> >> mike
> >> Mike Finley, http://www.efikim.co.uk
Received on Fri Feb 20 21:42:18 2004