RE: Calculating Scan Size

Eric,

I am just curious how you are able to work on files that are too
large to fit on a CD? It takes my Mac G4 forever to make changes in
Photoshop on anything larger than 700mb-800mb.

Sandy

>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
>4101 Commerce Street
>Suite 9
>Dallas, TX 75226
>http://e.neilsen.home.att.net
>http://ericneilsenphotography.com
>
>
>> -----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 Sat Feb 21 10:00:33 2004