On 02/03/2011 05:35 PM, Christoph Gohlke wrote: > > > On 2/3/2011 6:50 PM, Eric Firing wrote: >> On 02/03/2011 03:04 PM, Benjamin Root wrote: >> >>> Also, not to sound too annoying, but has anyone considered the idea of >>> using compressed arrays for holding those rgba values? >> >> I don't see how that really helps; as far as I know, a full rgba array >> has to be passed into agg. What *does* help is using uint8 from start >> to finish. It might also be possible to use some smart downsampling >> before generating the rgba array, but the uint8 route seems to me the >> first thing to attack. >> >> Eric >> >>> >>> Ben Root >> > > Please review the attached patch. It avoids generating and storing > float64 rgba arrays and uses uint8 rgba instead. That's a huge memory > saving and also faster. I can't see any side effects as > _image.fromarray() converts the float64 input to uint8 anyway.
Christoph, Thank you! I haven't found anything wrong with that delightfully simple patch, so I have committed it to the trunk. Back in 2007 I added the ability of colormapping to generate uint8 directly, precisely to enable this sort of optimization. Why it was not already being used in imshow, I don't know--maybe I was going to do it, got sidetracked, and never finished. I suspect it won't be as simple as for the plain image, but there may be opportunities for optimizing with uint8 in other image-like operations. > > So far other attempts to optimize memory usage were thwarted by > matplotlib's internal use of masked arrays. As mentioned before, users > can provide their own normalized rgba arrays to avoid all this processing. > Did you see other potential low-hanging fruit that might be harvested with some changes to the code associated with masked arrays? Eric > Christoph ------------------------------------------------------------------------------ The modern datacenter depends on network connectivity to access resources and provide services. The best practices for maximizing a physical server's connectivity to a physical network are well understood - see how these rules translate into the virtual world? http://p.sf.net/sfu/oracle-sfdevnlfb _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
