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Resampling
filters
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Resampling
is a technique that resizes an image using special filters.
The resample filter (or resize
algorithm) determines how pixels in a picture are affected when it is
resized. Using the right resample filter will keep your enlargements
looking great. Some filters add a blurring effect while others maintain
the hard edges between different areas of a picture.
The filter that generally gives
the best results is "Lanczos3". However, depending on your
thumbnail, you may get better results (smaller file size or higher image
quality) by trying out one of the other filters.
You can apply several resample filters
to your image:
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Triangle |
This filter
produces sharp transition lines and is relatively fast. It
produces reasonably good results with a little smoothing for
both reduction and magnification. |
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Hermite |
The Hermite
method creates noticeable smoothing but maintains a good degree
of sharpness. It is relatively fast. |
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Bell |
This filter
is also relatively fast and produces smooth image, bordering on
soft. |
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B-spline |
This method
does not produce sharp transitions and may cause excessive
blurring. It has the advantage of dampening noise and JPEG
artifacts. B-spline is one of the slower filters. |
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Lanczos3 |
This is a
slow method but it usually produces the sharpest images. Under
certain conditions, it may introduce some ringing patterns and
emphasize JPEG artifacts. |
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Mitchell |
Resizing with
this algorithm produces no sharp transitions and tends to be a
good compromise between the "ringing" effect of
Lanczos and "blurring" of other methods. The Mitchell
algorithm produces good results when enlarging pictures. It is
also one of the slower filters. |
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Nearest |
This filter
is recommended for small icons or lines/outlines. It works best
with illustrations containing non-anti-aliased edges. |
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Linear/Fast
Linear |
This is a
reasonably fast method that does not emphasize jagged edges, but
it does tend to blur the image slightly. |
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None |
The image is
simply stretched to the new size. This is the fastest method but
produces the least smoothing. |
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