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BUG: fix image handling of over, under, and indexed color mapping #6632

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efiring wants to merge 4 commits into from
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BUG: fix image handling of over, under, and indexed color mapping #6632

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c1ec9fa
FIX: carry through the over/under in resampling
tacaswell Jun 14, 2016
78a3ce7
Merge branch 'fix_over_under_images' of git://github.com/tacaswell/ma…
efiring Jun 21, 2016
dcaf13a
When using indexed colormapping in image, map before resizing.
efiring Jun 21, 2016
6df6ca1
pep8: long lines
efiring Jun 23, 2016
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37 changes: 24 additions & 13 deletions lib/matplotlib/image.py
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Original file line number Diff line number Diff line change
Expand Up @@ -356,21 +356,29 @@ def _make_image(self, A, in_bbox, out_bbox, clip_bbox, magnification=1.0,
if not unsampled:
created_rgba_mask = False

if A.ndim not in (2, 3):
raise ValueError("Invalid dimensions, got %s" % (A.shape,))

if A.ndim == 2:
A = self.norm(A)
# If the image is greyscale, convert to RGBA with the
# correct alpha channel for resizing
rgba = np.empty((A.shape[0], A.shape[1], 4), dtype=A.dtype)
rgba[..., 0:3] = np.expand_dims(A, 2)
if A.dtype.kind == 'f':
# If the image is greyscale, convert to RGBA with the
# correct alpha channel for resizing
rgba = np.empty((A.shape[0], A.shape[1], 4), dtype=A.dtype)
rgba[..., 0] = A # normalized data
rgba[..., 1] = A < 0 # under data
# TODO: get threshold from the norm or colormap
rgba[..., 2] = A > 1 # over data
rgba[..., 3] = ~A.mask
A = rgba
output = np.zeros((out_height, out_width, 4),
dtype=A.dtype)
alpha = 1.0
created_rgba_mask = True
else:
rgba[..., 3] = np.where(A.mask, 0, np.iinfo(A.dtype).max)
A = rgba
output = np.zeros((out_height, out_width, 4), dtype=A.dtype)
alpha = 1.0
created_rgba_mask = True
elif A.ndim == 3:
A = self.cmap(A, alpha=self.get_alpha(), bytes=True)

if not created_rgba_mask:
# Always convert to RGBA, even if only RGB input
if A.shape[2] == 3:
A = _rgb_to_rgba(A)
Expand All @@ -382,8 +390,6 @@ def _make_image(self, A, in_bbox, out_bbox, clip_bbox, magnification=1.0,
alpha = self.get_alpha()
if alpha is None:
alpha = 1.0
else:
raise ValueError("Invalid dimensions, got %s" % (A.shape,))

_image.resample(
A, output, t, _interpd_[self.get_interpolation()],
Expand All @@ -393,8 +399,13 @@ def _make_image(self, A, in_bbox, out_bbox, clip_bbox, magnification=1.0,
if created_rgba_mask:
# Convert back to a masked greyscale array so
# colormapping works correctly
hid_output = output
output = np.ma.masked_array(
output[..., 0], output[..., 3] < 0.5)
hid_output[..., 0], hid_output[..., 3] < 0.5)
# relabel under data
output[hid_output[..., 1] > .5] = -1
# relabel over data
output[hid_output[..., 2] > .5] = 2

output = self.to_rgba(output, bytes=True, norm=False)

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