| Issues with read_png and/or profiler [message #81000] |
Wed, 25 July 2012 08:51  |
hugh.ramp
Messages: 4
Registered: July 2012
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Junior Member |
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Hi all,
I'm running a fairly straight forward image correlation program, which should run fairly quickly (~O(n^4), I believe). However, the complexity seems to be rising much quicker than that, an 962x722 image with a 30x29 kernel takes ~16 hours (with profiler on), whereas a 640x480 image with the same kernel takes ~1.5 hours.
Using profiler to determine the source for the complexity, I found that the Time self(ms) for read_png() was ~60,000,000ms, i.e., 99% of the runtime was loading in the image. However, time+sub(ms) reports taking only ~100ms. I was under the impression that Time+sub should always include time self, no? In any case, I don't think read_png should be taking nearly 16 hours to read a 700,000 pixel image.
I was able to recreate the problem on a separate computer using the same code.
Profiler Snapshot here: http://i.imgur.com/xJelD.png
Cheers and thanks,
Hugh
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| Re: Issues with read_png and/or profiler [message #84687 is a reply to message #81000] |
Wed, 25 July 2012 10:01  |
hugh.ramp
Messages: 4
Registered: July 2012
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Junior Member |
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On Wednesday, 25 July 2012 09:51:54 UTC-6, Hugh wrote:
> Hi all,
>
> I'm running a fairly straight forward image correlation program, which should run fairly quickly (~O(n^4), I believe). However, the complexity seems to be rising much quicker than that, an 962x722 image with a 30x29 kernel takes ~16 hours (with profiler on), whereas a 640x480 image with the same kernel takes ~1.5 hours.
>
> Using profiler to determine the source for the complexity, I found that the Time self(ms) for read_png() was ~60,000,000ms, i.e., 99% of the runtime was loading in the image. However, time+sub(ms) reports taking only ~100ms. I was under the impression that Time+sub should always include time self, no? In any case, I don't think read_png should be taking nearly 16 hours to read a 700,000 pixel image.
>
> I was able to recreate the problem on a separate computer using the same code.
>
> Profiler Snapshot here: http://i.imgur.com/xJelD.png
>
>
> Cheers and thanks,
> Hugh
Profiler snapshot of 640x480 image: http://i.imgur.com/gfcq2.png
Profiler snapshot of 220x159 image: http://i.imgur.com/8L7yp.png
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