On Mar 30, 7:08 pm, David Given <[EMAIL PROTECTED]> wrote:
> saurabh wrote:
>
> [...]
>
> > The getPixel
> > function seems to be taking approx 1/100 of a second. Similarly,
> > checking whether each pixel satisfies the condition and then copying
> > it to Bitmap B also takes approx 1/100 second. Therefore, performing
> > these 2 operations for 547*450 = 246150 pixels takes a lot of time. Is
> > there any way to do this faster?
>
> I'd be inclined to copy all the pixel data out of the Bitmap into a
> int[] array of pixels; process it in-place; and then copy it all back in
> again. That way the heavy lifting --- the image processing --- occurs
> using simple array accesses, which should be way faster than doing
> method calls on Bitmap.
>
Thanks. That makes sense. The getPixels() and setPixels() calls are
quite fast and I need to call them only once. However, iterating over
the int[] array and checking each value is taking a lot of time. I've
reduced the time of the app by half but that is just not good enough.
> However...
>
> > I hope to use this for processing
> > each frame of a video in real-time. So, processing each picture must
> > not take more than a 1/20 of a second.
>
> ...not a chance!
>
> Hopefully this will be improved considerably when the JIT goes in, but
> right now simply filling an array of the right size with zeroes takes
> over a second.
>
> (I recently had to do something similar; I eventually got around it by
> pushing all the image processing off into native code via JNI, which of
> course is not officially supported and probably not a good choice unless
> you really need it.)
>
> --
> ┌─── ｄｇ＠ｃｏｗｌａｒｋ．ｃｏｍ ─────http://www.cowlark.com─────
> │ "I have always wished for my computer to be as easy to use as my
> │ telephone; my wish has come true because I can no longer figure out
> │ how to use my telephone." --- Bjarne Stroustrup
>
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