[poppler] Image optimization

Albert Astals Cid tsdgeos at yahoo.es
Thu May 19 13:47:01 PDT 2005

Georgeous, can this be applied to the splash outputdev too?


A Dijous 19 Maig 2005 19:54, Kristian Høgsberg va escriure:
> Hi,
> I've been looking into optimizing the slow image handling in poppler.
> As Jeff identifier earlier on, the color space conversion (surprisingly)
> is taking a lot of time.  Here's a patch that adds a getRGBLine()
> function to the color space object so we avoid a virtual function call
> per pixel, plus it converts to bytes instead of doubles in the 0-1
> range.  With this, the color space conversion disappears from the
> profile while maintaining the full generality of the color space
> conversion code.
> I'm thinking about adding an output format type to getRGBLine() so it
> would support a number of output format, specifically one that can be
> used directly with cairo.  Other than that, I'm pretty happy with this
> approach, here's some numbers:
> 	slow.pdf		23.6s	6.5s
> 	p59_1.pdf		17.5s	3.9s
> 	01-tifa's theme.pdf	8.7s	3.1s
> 	camj43004ind.pdf	9.9s	2.3s
> It's still not really fast, but at this point we're hitting libpixman's
> pixman_compositeGeneral at 72% (in one of the test documents).  That
> function is pretty slow, so that we we're able to trump that in the
> profile says something about how slow the current color space conversion
> code is.
> I'll commit this in a day or two when I've filled out the missing parts
> (e.g. indexed color spaces).
> cheers,
> Kristian

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