Michael:
I commented on the patch here:
https://github.com/matplotlib/matplotlib/issues/545
In short...it works!
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The demand for IT networking professionals continues to grow, and the
demand for specialized
Thanks for looking into this deeper.
Agg requires image buffers to be premultiplied, as described in the
third bullet point here. (It's not exactly clear, to say the least, but
that's what I take it to mean, and also from reading the code).
All sounds reasonable Mike; I do agree that patching the agg source
code is not that desirable; I was operating under the (incorrect)
assumption that most, if not all, backends used straight alpha.
I'll certainly test the patch tonight, but I can only test it under
wxAgg reasonably, which is one
On 10/21/2011 09:49 AM, Daniel Hyams wrote:
All sounds reasonable Mike; I do agree that patching the agg source
code is not that desirable; I was operating under the (incorrect)
assumption that most, if not all, backends used straight alpha.
I'll certainly test the patch tonight, but I can
On Friday, October 21, 2011, Michael Droettboom md...@stsci.edu wrote:
On 10/21/2011 09:49 AM, Daniel Hyams wrote:
All sounds reasonable Mike; I do agree that patching the agg source
code is not that desirable; I was operating under the (incorrect)
assumption that most, if not all, backends
I've looked all over the place through both the Python and C code, and
I don't see any premultiplication of alphas at any stage before the
pixels are passed off to agg, and neither can I find any place where
the alphas are unmultiplied on the way back from agg to the backend
for rendering.
It's
You are right that Agg is doing the resizing here. Agg expects
premultiplied alpha. See [1] for information about what that means.
[1] http://en.wikipedia.org/wiki/Alpha_compositing
After Agg interpolates the pixel values, to prevent oversaturation it
truncates all values to be less than
Ah, thanks so much Michael! That explanation helps a great deal; I
was always considering things in straight alpha format, not even
knowing that there was alternative.
I'll play with this tonight; I don't see any problem getting the thing
working, though, now that I know what agg expects to
