Julie, I am a big fan of capturing every pixel that the hardware device can capture without interpolation. You should check the specs on your scanner. My Epson 1680 can scan at several resolutions, but 1600 ppi (pixels per inch) is the maximum resolution without interpolation. It has other settings from 72 up to 12800 ppi, but that is not a good strategy. If you capture the maximum real pixels that the hardware device can produce, you have the best file possible which you can then make smaller according to your specs, but never larger.
Robert Hickerson Photograher Spencer Museum of Art -----Original Message----- From: mcn-l-bounces at mcn.edu [mailto:[email protected]] On Behalf Of Richard Urban Sent: Tuesday, November 21, 2006 4:22 PM To: Museum Computer Network Listserv Subject: Re: [MCN-L] Question about Scanning Negatives Julie, I would avoid using "scaling" since this often means the scanner will be interpolating (aka making guesses) data from what it can't see on the original. This would also be the case in taking lower resolution images and increasing their DPI after scanning. It can be done, but it no longer accurately represents the original. Regarding resolutions, this is one of those cases where it may be better to look at the pixels on the longest dimension, rather than DPI. If your materials are all the same size you can calculate a target dpi for them. Taking CDL's best practice of 4,000 pixels on the longest dimension would give you ~1150 dpi for 3.5 photographic negatives. Some helpful tools are the Excel sheets from the Technical Advisory Service for Images, which let you estimate storage requirements based on resolution, bit depth and size. http://tasi.ac.uk/resources/ toolbox.html Setting your scanner to the "highest resolution possible" might not buy you anything, as film or prints have their own resolution. At some point you may be capturing more information than the original film holds, which may not be efficient use of storage space (and lets not forget that good digital preservation means you have multiple copies to prevent a single point of failure and should be included in your storage estimates). Richard Urban rjurban at uiuc.edu On Nov 21, 2006, at 3:32 PM, Julie Grob wrote: > Hello, > > We are about to begin scanning a large group of early 20th century > negatives. They are about 3.5" square. We will be creating master > TIFFs of > course, but we would like to be able to print larger than 3.5" > images. Is > it better to scale up and scan them at something like 200%, or to > increase > the resolution from 600 dpi to a higher dpi? > > Thanks in advance, > Julie Grob > > > Julie Grob > Digital Projects and Instruction Librarian > Special Collections > 114 University Libraries > University of Houston > Houston, TX 77204-2000 > (713) 743-9744 > jgrob at uh.edu > > _______________________________________________ > You are currently subscribed to mcn-l, the listserv of the Museum > Computer Network (http://www.mcn.edu) > > To post to this list, send messages to: mcn-l at mcn.edu > > To unsubscribe or change mcn-l delivery options visit: > http://toronto.mediatrope.com/mailman/listinfo/mcn-l _______________________________________________ You are currently subscribed to mcn-l, the listserv of the Museum Computer Network (http://www.mcn.edu) To post to this list, send messages to: mcn-l at mcn.edu To unsubscribe or change mcn-l delivery options visit: http://toronto.mediatrope.com/mailman/listinfo/mcn-l
