I should have left more comments about my change.
The issue is that the current slicing algorithm sometimes fails with
"_draw_unsampled_image" which support arbitrary affine transformation
of the image. The slicing gets wrong when the image is significantly
skewed or rotated. So, as a temporary measure, I simply wanted to
disable the slicing until we have a correct algorithm in place.
I guess a quick (still temporary) fix is to check if affine transform
is needed, and do the slicing if not.
Something like below. The condition is not exactly correct, but I
think it would work in most of cases.
I actually didn't test the patch. I'll be out of town until the end of
On a second thought, I think it should not be difficult to workaround
the slicing thing for arbitrary affine transform. I'll think about the
whole issue again when I get back. If you have a better idea, please
go ahead and implement.
diff --git a/lib/matplotlib/image.py b/lib/matplotlib/image.py
index 7c1128f..b65f446 100644
@@ -248,9 +248,14 @@ class _AxesImageBase(martist.Artist, cm.ScalarMappable):
+ if self._image_skew_coordinate:
+ no_slice = True
+ no_slice = False
im, xmin, ymin, dxintv, dyintv, sx, sy = \
- self.axes.viewLim, noslice=True)
+ self.axes.viewLim, noslice=no_slice)
if im is None: return # I'm not if this check is required. -JJL
On Tue, Jun 22, 2010 at 8:45 PM, Eric Firing <efiring@...229...> wrote:
In AxesImageBase._draw_unsampled_image, there is a call to
_get_unsampled_image(...noslice=True). When using imshow(Z,
interpolation='nearest'), this defeats the slicing that makes such a
difference when zooming and panning a small chunk of a large image. Changing
it to False makes imshow work better; I don't understand why one would ever
want noslice=True. Am I missing something? Can we just change it to False?
Or remove the noslice option and kwarg entirely?