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The Google Books computer optical scan of page 92 of With the yacht and camera in eastern waters, by the 9th Earl of Cavan, exhibits some distortion, probably due to page motion during scan. What is this kind of distortion called, or how is it referred to? page 92 of book

Edit 1: (Pursuant to Eduardo's comments) Scrolling down to page 98 one can see what appears to be part of the page-flipper device raising the left-hand page, causing it to crease along the line at edge of distortion.

bottom edge of page 98

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DSLs are off-scope? (Domain specific languages — each field of specialization may define its own terms, which may or may not have the same meaning in general English usage.) –  Kris Dec 30 '11 at 6:10
    
@Kris Although I'm concerned that the question may be closed as "too localized", I am not aware of it conflicting with anything stated in the FAQ. Actually, the FAQ seems to be silent on the whole "too localized" issue, which may be a good topic to take up in Meta –  jwpat7 Dec 30 '11 at 6:28
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2 Answers 2

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That image looks a lot like a curvature distortion (you can see how the distortion follows a line where the paper seems to be lifted in the bottom and wrinkled as you start going through it upwards).

There are algorithms that attempt to correct that type of distortion called curvature correction algorithms. Here is an example of the final effect of them:

curvature distortion algorithm in action

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You may have identified the problem - as I looked at other distorted pages in the book (after posting question), the "motion" notion seemed less & less likely. Maybe the enlarged part was closer to the imager due to the presented page not being flat. Note, Google's text recognition didn't cope with the distortion. –  jwpat7 Dec 30 '11 at 7:21
    
Maybe if you had access to the scan of the other side of the page (page 91 or 93), you would be able determine if the page was actually wrinkled. I wouldn't expect such a big distortion on the other side of the page, but maybe a slighter indication would suffice. –  Eduardo Dec 30 '11 at 7:59
    
All the pages are visible by scrolling at first link, but those near 92 are not conclusive. However, scrolling down to page 98, one can see what apparently is the curved edge of page, and apparently the page-flipper device (partly visible about 1" above the page number on page 99) is raising the left-hand page, causing it to crease along the line at edge of distortion. See question edit –  jwpat7 Dec 30 '11 at 8:19
    
Very interesting find! –  Eduardo Dec 30 '11 at 9:09
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Various wave-type distortion algorithms can be applied to images to modify as needed.

enter image description here

Could a glitch in the scanning system cause a similar distortion? The document itself need not have been physically distorted, moved, disturbed or otherwise changed in anyway.

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Prompted by your reply, I searched for how Google Books does scans; a cnet.com article has some pictures and a patent link, and from the description there the distortion obviously could not have happened. :) –  jwpat7 Dec 30 '11 at 7:49
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