Re: scanning prints larger than ISO A4 size

Thanks for those who responded to my questions on ways to scan prints
larger than A4 size. This is a report about two ways I tried.

Kate, Dan and Eric commented on scanning piecewise and stitching them.
I scanned pieces using fixed exposure and without histogram correction
(but with other corrections that do not depend on the image
statistics), so that the pieces are scanned at 400dpi into TIFF files
at the same condition.

For the stitching part, I've tried Photoshop CS's Photomerge function
and Gimp's Pandora plugin. Photomerge was very easy and perfect
without tweaking a single thing. At least with fixed exposures and no
histogram correction, it was a pushbutton operation and the perfect
stitching was done in matter of seconds. For this I used a PC with
3GHz clock and 2GB memory (that's not my machine, ha ha). Pandora was
more of an aid for manual stitching than automated stitching tool, so
I had to adjust rotation angle and aligh pieces by hand. I did this on
a laptop with 368MB memory with Crusoe 933MHz processor, and it did
take a lot longer time as Eric said.

Jack and Alex commented on the digital SLR route. I used Olympus E-20
once with studio flash setup and once with barebulb flash. This
approach gave me mixed results. Color rendition of toned prints was
better, than my scanner, requiring much less effort on correction and
still closer to what I see. But the contrast of the scanned data was
not high enough, requiring some curve tweaking. Bigger problem is
reflection with somewhat curly prints.

I think if I adjust scan parameters the scan-stitch method will
require much less color correction and will be easier and higher
quality than digital SLR method.

So far I've used images from both methods to make a PDF portfolio. I
haven't decided what to do with the quality of 400dpi scans of large
prints but I might want to print some of them later.

--
Ryuji Suzuki
"Well, believing is all right, just don't let the wrong people know
what it's all about." (Bob Dylan, Need a Woman, 1982)