* Re[2]:[9fans] image resampling
@ 2002-04-15 15:53 steve.simon
2002-04-15 15:54 ` [9fans] " Boyd Roberts
0 siblings, 1 reply; 2+ messages in thread
From: steve.simon @ 2002-04-15 15:53 UTC (permalink / raw)
To: 9fans
Re OS-X, The simple answer is, no idea.
They maybe using hardware acceleration of the graphics device?
Maybe OS-X is not resampling a full 24 bit RGB image as the plan9 one is?
There is a trick you can do throwing memory at the problem, if your image is 8
bits
deep and you have 8 coefficients then you have 64K entry
lookup table instead of a multiplier. I haven't tried this for
years - it was a win in the days of slow multiply instructions, probably
irrelevant now.
The vertical pass can cause rather nasty RAM access patterns and may
upset the CPU's data cache, Rotating the array by 90 degrees and reapplying the
same horizontal filter code (though not the coefficients -
non-square aspect ratios) might help.
All a bit speculative though, Russ's code looks a very sane implementation to
me.
-Steve
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* Re: [9fans] image resampling
2002-04-15 15:53 Re[2]:[9fans] image resampling steve.simon
@ 2002-04-15 15:54 ` Boyd Roberts
0 siblings, 0 replies; 2+ messages in thread
From: Boyd Roberts @ 2002-04-15 15:54 UTC (permalink / raw)
To: 9fans
steve.simon@snellwilcox.com wrote:
>
> Re OS-X, The simple answer is, no idea.
Geoff Collyer may be able to answer that one.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2002-04-15 15:54 ` [9fans] " Boyd Roberts
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