Settings for catalog and 'resample types' explain?

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obelisk
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Joined: Fri Jan 09, 2009 9:54 am

Settings for catalog and 'resample types' explain?

Post by obelisk » Thu Sep 29, 2016 8:52 am

Can someone explain the thumbs->catalog settings meaning?

Also the batch convert-> what's resample types?

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helmut
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Location: Frankfurt, Germany

Re: Settings for catalog and 'resample types' explain?

Post by helmut » Fri Sep 30, 2016 9:50 am

obelisk wrote:Can someone explain the thumbs->catalog settings meaning?
Basically the catalog is a database containing cached thumbnail images and meta information (categories and ratings) of images. The catalog allows for quick browsing by caching the thumbnail images and searching for images by category or rating, for example.
obelisk wrote:Also the batch convert-> what's resample types?
Resampling is used whenever changing the size of an image. There are various algorithms/approaches/methods (=resampling types) that lead to different results. See https://en.wikipedia.org/wiki/Image_scaling

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XnTriq
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Re: Settings for catalog and 'resample types' explain?

Post by XnTriq » Fri Sep 30, 2016 2:30 pm

XnTriq ([url=http://newsgroup.xnview.com/viewtopic.php?p=109743#p109743]bicubic resize ?[/url]) wrote:
Algorithms currently available in XnView v1.9 (Image » Resize):
  1. Nearest Neighbour
  2. Bilinear
  3. Hermite (Cubic Hermite spline?)
  4. Gaussian
  5. Bell
  6. Bspline
  7. Mitchell
  8. Lanczos (3-lobe)
  9. Hanning
foxyshadis ([url=http://newsgroup.xnview.com/viewtopic.php?t=3496]Info about Resampling algorithms[/url]) wrote:Mitchell is bicubic.

Agreed that some of the resizers aren't very useful. Could be worse, could be the full list of imagemagick resizers. :p Gauss, bell, and bspline are almost indistiguishable, and often only useful as specialized effects, not generic outputs; in general they're too close to bilinear to even matter. There are a wide range of bsplines but this one doesn't retain much sharpness. Hermite is practically indistiguishable from Mitchell - in fact it's one of the degenerate cases of the Mitchell/Netravali filter, iirc. Those who actually care about these others would probably also care enough to want their tunable parameters as well, or more advanced non-separable resize kernels.

So point, bilinear, bicubic, and lanczos would seem to be enough for anyone using batch resize. If you wanted to emulate photoshop, you could have a bicubic smoother (lower "c") like photoshop, to fill that halfway point in.

[...]

Point, box, and nearest neighbor are (usually) synonyms for the same thing, [...]
Nicky Page ([url=http://nickyguides.digital-digest.com/bilinear-vs-bicubic.htm]Bicubic Resizing vs Bilinear[/url]) wrote:Everyone uses Bicubic resizing religiously when they make DivX movies or any time they resize pictures in photo editing software. I have suggested that it is best to use Bilinear to shrink images and Bicubic to enlarge them. In fact I believe it is a rule that shouldn't be broken. But then again there is mixed opinion even among experts on this matter. Digital photo experts JASC (makers of Paint Shop Pro) comment: "Use the Bilinear Resampling method for shrinking these images and Bicubic for enlarging them". Whereas the help file of Adobe Photoshop just mentions that Bicubic is more exact method for resizing. In actual fact Bicubic is more precise, but only when it comes to enlarging. When it comes to shrinking its exactness can actually produces pixelation, because to shrink an image pixels must be discarded anyway.

The following shows examples demonstrating this effect. There are reasons you may prefer Bicubic shrinking methods though. Namely, if sharpness is absolutely vital and pixelation problems are less important.

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