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Re: Incredibly slow SRT operation when scaling to small size
Posted: 2013-09-27T20:02:37-07:00
by fmw42
snibgo wrote:We often suffer from brevity; I should have said it resembles the infinite horizon issue.
No problem. Perhaps I took your comment too literally and more importantly did not read his original post carefully enough. So, I became confused and totally missed the real issue and you had it pinned exactly.
Re: Incredibly slow SRT operation when scaling to small size
Posted: 2013-10-10T17:54:18-07:00
by anthony
When you get a slow distortion on an image involving extreme reducitons. my first suggestion would to turn off EWA filtering.
That is add -filter point
This means only ONE (unscaled) interpolative lookup is used for each output pixel (at most a 16 pixel lookup limit, depending on the current interpolation setting). It will not attempt to merge (according to the current filter) a large elliptical area of pixels for each output pixel.
If this works you can try using a super-sampling method. That should work especially well for SRT distortions whcih are uniformly scaled across the whole image.