Subject:
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Re: Scans uploaded, critique wanted
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Newsgroups:
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lugnet.db.scans
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Date:
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Wed, 27 Oct 1999 15:42:41 GMT
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Viewed:
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1950 times
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Kevin Loch wrote:
>
> That sounds like a good idea BUT,
>
> When you start with a JPEG, do something (even lossless rotation),
> and recompress as JPEG you exaggerate the JPEG artifacts. This is why
> it's important for the original scanner to rotate/crop/size the images
> BEFORE saving in a lossy format like JPEG.
>
> Of course I couuld rotate/resize/crop the JPEG's and save them in a
> lossless format like PNG...
There is a program called jpegtran which will rotate JPEGs by any
multiple of 90 degrees without decompressing the file, i.e. just by
moving bits around in the jpg file. This means that there is _no_ loss
in quality. But (there always is a but, isn't there?) it may create some
artefacts at the edge of the picture if the picture size is not a
multiple of the block size (8 or 16 pixels). This seems to mean to me
that you loose at most 16 pixels width and height. There even seems to
be an option to automatically clip off those offending pixels. Worth a
try, perhaps?
Regards,
Johannes.
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Message is in Reply To:
 | | Re: Scans uploaded, critique wanted
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| That sounds like a good idea BUT, When you start with a JPEG, do something (even lossless rotation), and recompress as JPEG you exaggerate the JPEG artifacts. This is why it's important for the original scanner to rotate/crop/size the images BEFORE (...) (25 years ago, 22-Oct-99, to lugnet.db.scans)
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