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Old Nov 20, 2005, 10:33 AM   #1
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From what can be gained from "on-line" comparisons; to my eyes, Qimage Pyramidal, Genuine Fractals, & PhotoZoom Pro's latest version of S-Spline appear to be near equal in quality, among the current best available,--- with S-Spline perhaps having an 'edge" in some respects.

http://www.americaswonderlands.com/d...erpolation.htm

Two, yet unreleased, methods, however,appear to bestthose currently available.

One called "Smart Edge 2" appears to be visibly superior;

http://audio.rightmark.org/lukin/gra...resampling.htm

And another called RS-M-Spline 55 appears to be best of all ;

http://www.resampling.narod.ru/

Perhaps optimal quality, artifact free interpolation is becoming a realization

Leigh
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Old Nov 21, 2005, 4:31 PM   #2
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There are two problems with some of the sharper methods available. The first problem is that of speed. Many of these high end interpolation algorithms take several orders of magnitude longer to compute, making them next to useless for things like real-time print processing. The second issue is that many of these algorithms make some edges too smooth and sharp and that can break the correlation between focus (depth of field) and overall sharpness making the image look a bit "weird" because there simply isn't enough data in the original to determine that the edge should be sharp/soft. There's only so much you can do with limited data, and some of these algorithms push the envelope a little too far in my opinion. Nevertheless, in some cases, they do work better than anything else but you have to pick and choose what type of images you use them on.

Mike
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Old Nov 23, 2005, 7:20 AM   #3
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Quote:
Many of these high end interpolation algorithms take several orders of magnitude longer to compute, making them next to useless for things like real-time print processing
Mike,

If you're thinking of developing your sharpening algorithms further, don't be put off by speed considerations for a new algorithm. After all, if I choose 'print to file' I only have to use QImage once to do the actual upsampling and sharpening, then I can just print the TIF file as many times as I like using (e.g.) Photoshop.

Some people don't mind waiting a bit longer for the best quality result. This consideration crops up in other contexts as well. For example, the Epson 2200/2100 is slower than its Canon rivals, but because I prefer the look of the Epson prints I don't care about that.

Just my two penn'orth,

Alan

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Old Nov 26, 2005, 10:04 AM   #4
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alanrew wrote:
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Some people don't mind waiting a bit longer for the best quality result. This consideration crops up in other contexts as well. For example, the Epson 2200/2100 is slower than its Canon rivals, but because I prefer the look of the Epson prints I don't care about that.

Just my two penn'orth,

Alan
Agreed... up to a point. I've tested some of the latest algorithms though, and they are not just slower, they are nearly unusable. We're talking 20 - 30 times slower with maybe a 5% improvement in quality. That means just processing an 8x10 will go from less than a minute to 20 minutes or more. Most people aren't going to wait 20 minutes to process a single 8x10 image just for a 5% improvement. It's impractical for the amount of improvement you get so the cost far outweighs the benefit.

As with a lot of things, algorithms can improve over time, so if I see any of these that get into range (like maybe only 2-4 times slower than Qimage's slowest pyramid interpolation) I'll certainly take another look.

Mike
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