Following on a recent thread pointing to the "scan once, readjust master from there" I have a high end problem. I'm the imaging guy (among various hats, shoot AS 4x5 for fun) at a midsized museum and have been charged with scanning some plates from an old (1828) and even rarer book (book is not bound, so no issues there). I have an Epson 4990. Scan options are:
- scan at 2400 dpi to get 2.26 GB 48 bit RGB .tif file. Then resize image to fit on CD-ROM for archiving (700 MB 48 bit RGB .tif). DVDs still have too many cross-platform issues, so is not an option.
[LZW compression *increased* file size to 2.83 GB].
- Take 2400 dpi 48 bit scan and jpeg it at highest quality with associated 24 bit conversion, producing files of around 250-320 MB. Neither the Epson scan nor Silverfast will allow me to scan at higher resolution than 2400 dpi because of some file size limitation.
So the options for archiving on CDs are "small" 48 bit RGB .tif, or pixel-wise larger highest quality jpeg in 24 bit RGB. Needless to say, that the jpeg master would be converted to .tif before any work is done on it. The question is, what produces overall the better master file?
I think intuitively that the jpeg route is better as there is so much more pixel information available, which will outweigh the loss of tonality due to the 48 to 24 bit conversion; tonality is not that much of an issue as the images are some sort of lithography (I think), so more colorized line-art than continuous tone photographs. The tif would be area-wise over three times smaller, or in linear dimension around 1.7-1.8 times smaller. Am I overlooking something?