{"id":298,"date":"2020-12-23T22:38:40","date_gmt":"2020-12-24T05:38:40","guid":{"rendered":"http:\/\/wiki.lillerant.com\/?p=298"},"modified":"2020-12-23T22:38:40","modified_gmt":"2020-12-24T05:38:40","slug":"scanning-flat-positives","status":"publish","type":"post","link":"http:\/\/wiki.lillerant.com\/?p=298","title":{"rendered":"Scanning flat positives"},"content":{"rendered":"\n

In trying to archive some prints I have before they inevitably yellow, I invested in a scanner and Silverfast Ai. They’re printed materials, so require descreening<\/a>. It’s important to scan materials that need descreening at whole multiples of the native optical resolution. The best trade-off for mine ended up being 1280ppi.<\/p>\n\n\n\n

Some of these prints are far larger than the scanner bed, so I scan them in multiple passes, with about 20% overlap. Then I use photoshop to stitch them together.<\/p>\n\n\n\n

I discovered an unusual phenomenon in that the auto stitching mechanism sometimes had great difficulty getting a match, and when I attempted it manually it became apparent that the same sections, scanned multiple times, were different dimensions. So the overlap(s) were not perfect copies of one another.<\/p>\n\n\n\n

I found literally ONE <\/a>reference to this on the internet, so thought I’d place this information here in case that site ever goes down:<\/p>\n\n\n\n

After digging into the issue further a few days ago, it seems to be related to CCD scanners specifically, as opposed to CIS scanners, due to the particular use of a lens to transfer the image data to the CCD sensor.<\/p>

Related Links:
CCD or CIS<\/a>\u00a0(web – by the WideTEK scanner folks)
CIS vs. CCD<\/a>\u00a0(pdf brochure from Paradigm Imaging Group)<\/p>

So it appears that the best color capturing happens with CCD, but you also get lens distortion with that. I suppose if someone is mainly scanning documents, a CIS scanner may be the way to go (in actuality, probably just fine for photos, too).<\/p>Josh T. on forums.anandtech.com<\/cite><\/blockquote>\n\n\n\n

The lens distortion is not uniform, nor symmetrical. The best option I’ve found is to use Photoshop’s Photomerge “auto”, which allows scaling, rotation and distortion (meant for photographs). I was really hoping to be able to pull off something approaching archival quality (I calibrated and profiled the scanner), but having to distort dimensions to successfully stitch is really disappointing.<\/p>\n\n\n\n

I’m almost <\/em>crazy enough to switch to the method of using a DSLR and macro lens, undoing lens distortion before stitching.<\/p>\n\n\n\n

Almost… <\/p>\n","protected":false},"excerpt":{"rendered":"

In trying to archive some prints I have before they inevitably yellow, I invested in a scanner and Silverfast Ai. They’re printed materials, so require descreening. It’s important to scan materials that need descreening at whole multiples of the native optical resolution. The best trade-off for mine ended up being 1280ppi. Some of these prints … Continue reading Scanning flat positives<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"http:\/\/wiki.lillerant.com\/index.php?rest_route=\/wp\/v2\/posts\/298"}],"collection":[{"href":"http:\/\/wiki.lillerant.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wiki.lillerant.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wiki.lillerant.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/wiki.lillerant.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=298"}],"version-history":[{"count":1,"href":"http:\/\/wiki.lillerant.com\/index.php?rest_route=\/wp\/v2\/posts\/298\/revisions"}],"predecessor-version":[{"id":299,"href":"http:\/\/wiki.lillerant.com\/index.php?rest_route=\/wp\/v2\/posts\/298\/revisions\/299"}],"wp:attachment":[{"href":"http:\/\/wiki.lillerant.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=298"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wiki.lillerant.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=298"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wiki.lillerant.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=298"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}