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Re: how to read images fast with Apple Java?


On Sep 19, 2008, at 12:35 AM, Bill Janssen wrote:

Greg Guerin <email@hidden> wrote:

I don't have a specific answer, just a strategy for finding answers. 

Sorry, not interested.  I'm interested in knowing if anyone out there
knows the specific answer, and is willing to share it.

If the PNG-reading time were reduced to exactly 0 ms (i.e. infinitely
fast), would the overall task then be fast enough for you to call it
successful?

That would be superb. How do I do it?


I'm reasonably certain that was part of Greg's strategy for finding answers. That is, suppose that the PNG-reading time was taken out of the equation, in that it was so fast that it was essentially instantaneous. At that point, would your app be fast enough? This is related to Amdahl's law (http://en.wikipedia.org/wiki/Amdahl%27s_law) and the concept of diminishing returns. Which I'm sure you already know.

Example for those who slept through that lecture:
Suppose for each image, it takes 200ms to read as PNG, 40ms to frobnicate, 120ms to bazzle it, 98ms to apply the quuux^2 transform, and 150ms to write out a transformed image. Your current time would be 608 ms/sec.

If you manage to increase your reading speed so it now takes only 100ms, your overall process per image is 508ms. Thus you've halved your reading time, but the overall process only sped up by 16%. Any further improvements to reading speed will make less difference to the overall process.


Bill 

Dave Watson




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References: 
 >Re: how to read images fast with Apple Java? (From: Greg Guerin <email@hidden>)
 >Re: how to read images fast with Apple Java? (From: Bill Janssen <email@hidden>)



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