> Eric Firing wrote: > > Andrew Hawryluk wrote: >> The interpolation algorithm used in imshow() can produce spurious >> results, as has been noted before: >> >> _http://article.gmane.org/gmane.comp.python.matplotlib.general/12062_ >> >> This happens because the data is converted to RGB before the >> interpolation/resampling, rather than after. How hard would it be to >> reverse this so that the data array is first interpolated & resampled
>> and then converted by cmap to RGB? > > To me, it looks very hard. The color mapping is done first, in python, and not repeated with > every draw. The interpolation is done by agg at rendering time. Logically, I don't know any > reason why agg shouldn't do what you suggest: interpolate the scalar field and then convert > to rgb. > Maybe agg can do it this way. If so, it would still take quite a bit of work by someone > comfortable with agg (i.e., not me) to make the change. > > Eric Ah, that is certainly more difficult that what I would be prepared to attempt, which is unfortunate because it would greatly improve the output and reduce the interpolation's computation by a factor of three (RGB). Until someone feels up to the challenge, I will just add a manual interpolation step when necessary for my data. e.g.: import matplotlib.pyplot as p import numpy as n import scipy.ndimage a = n.random.normal(size=(10,10)) p.imshow(a,interpolation='nearest') # the actual data p.figure() p.imshow(a,interpolation='bicubic') # an AGG interpolation of the RGB values b = scipy.ndimage.zoom(a,25)[:-24,:-24] p.figure() p.imshow(b) # the data interpolated at 25x magnification with a cubic spline Thanks for the information, Andrew ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
