Re: Shrinking bitmaps
At 04:25 AM 2/4/02 +1300, you wrote:
>
>Graeme,
>
>I do not want to get into another stupid argument across the Tasman, rugby
>and cricket fanatics generate enough of them already, but have done any
>tests to support your claims?
Umm... yes.
I used the test demo you posted a few days ago that uses the 640x480 windows
setup bitmap.
i put each resize routine in a 200 iter loop. first i got them to do 660x660,
then 1280x960. Both times my routine was twice as fast. Then i tried 6400x4800
Your routine caused an out of memory error. Mine worked fine
>
>I just did a quick speed test expanding a 64x64 bitmap to twice its size,
>and my *unoptimized* routine seems to be almost 4 times faster than yours.
Was it? I'll remember that next time I'm resizing a postage stamp.
>I have not attempted any measurements regarding memory usage, but casual
>inspection reveals that there should be no significant difference between
>the two offerings.
The thing that has escaped your casual inspection is the way the return
bitmap is built. Your routine uses a sequence the size of the target bitmap.
My routine expands the bitmap in the x-axis, then builds the return sequence
by making multiple pointers to the first level elements of the x-expanded
bitmap. This is why my routine is faster and uses less memory.
Pity bout the cricket though ...... :(
>
>jiri
>
graeme
|
Not Categorized, Please Help
|
|
