Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Appearance settings

Commit 0c5adf9

Browse filesBrowse files
jklymakjklymak
committed
TST: add tests for up and down sampling for interpolation stage
1 parent 2360c59 commit 0c5adf9
Copy full SHA for 0c5adf9

File tree

3 files changed

+67
-9
lines changed
Filter options

3 files changed

+67
-9
lines changed

‎lib/matplotlib/axes/_axes.py

Copy file name to clipboardExpand all lines: lib/matplotlib/axes/_axes.py
+8-5Lines changed: 8 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -5791,11 +5791,14 @@ def imshow(self, X, cmap=None, norm=None, *, aspect=None,
57915791
which can be set by *filterrad*. Additionally, the antigrain image
57925792
resize filter is controlled by the parameter *filternorm*.
57935793
5794-
interpolation_stage : {'data', 'rgba'}, default: 'data'
5795-
If 'data', interpolation
5796-
is carried out on the data provided by the user. If 'rgba', the
5797-
interpolation is carried out after the colormapping has been
5798-
applied (visual interpolation).
5794+
interpolation_stage : {'antialiased', 'data', 'rgba'}, default: 'antialiased'
5795+
If 'data', interpolation is carried out on the data provided by the user.
5796+
If 'rgba', the interpolation is carried out in RGBA-space after the
5797+
color-mapping has been applied (visual interpolation). If 'antialiased',
5798+
then 'rgba' is used if downsampling, or upsampling at a rate less than 3.
5799+
If upsampling at a higher rate, then 'data' is used.
5800+
See :doc:`/gallery/images_contours_and_fields/image_antialiasing` for
5801+
a discussion of image antialiasing.
57995802
58005803
alpha : float or array-like, optional
58015804
The alpha blending value, between 0 (transparent) and 1 (opaque).

‎lib/matplotlib/image.py

Copy file name to clipboardExpand all lines: lib/matplotlib/image.py
+20-4Lines changed: 20 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -421,7 +421,21 @@ def _make_image(self, A, in_bbox, out_bbox, clip_bbox, magnification=1.0,
421421
if not unsampled:
422422
if not (A.ndim == 2 or A.ndim == 3 and A.shape[-1] in (3, 4)):
423423
raise ValueError(f"Invalid shape {A.shape} for image data")
424-
if A.ndim == 2 and self._interpolation_stage != 'rgba':
424+
425+
# if antialiased, this needs to change as window sizes
426+
# change:
427+
interpolation_stage = self._interpolation_stage
428+
if interpolation_stage == 'antialiased':
429+
pos = np.array([[0, 0], [A.shape[1], A.shape[0]]])
430+
disp = t.transform(pos)
431+
dispx = np.abs(np.diff(disp[:, 0])) / A.shape[1]
432+
dispy = np.abs(np.diff(disp[:, 1])) / A.shape[0]
433+
if (dispx < 3) or (dispy < 3):
434+
interpolation_stage = 'rgba'
435+
else:
436+
interpolation_stage = 'data'
437+
438+
if A.ndim == 2 and interpolation_stage == 'data':
425439
# if we are a 2D array, then we are running through the
426440
# norm + colormap transformation. However, in general the
427441
# input data is not going to match the size on the screen so we
@@ -552,7 +566,7 @@ def _make_image(self, A, in_bbox, out_bbox, clip_bbox, magnification=1.0,
552566
cbook._setattr_cm(self.norm, vmin=s_vmin, vmax=s_vmax):
553567
output = self.norm(resampled_masked)
554568
else:
555-
if A.ndim == 2: # _interpolation_stage == 'rgba'
569+
if A.ndim == 2: # interpolation_stage == 'rgba'
556570
self.norm.autoscale_None(A)
557571
A = self.to_rgba(A)
558572
alpha = self._get_scalar_alpha()
@@ -787,12 +801,14 @@ def set_interpolation_stage(self, s):
787801
788802
Parameters
789803
----------
790-
s : {'data', 'rgba'} or None
804+
s : {'data', 'rgba', 'antialiased'} or None
791805
Whether to apply up/downsampling interpolation in data or RGBA
792806
space. If None, use :rc:`image.interpolation_stage`.
807+
If 'antialiased' we will check upsampling rate and if less
808+
than 3 then use 'rgba', otherwise use 'data'.
793809
"""
794810
s = mpl._val_or_rc(s, 'image.interpolation_stage')
795-
_api.check_in_list(['data', 'rgba'], s=s)
811+
_api.check_in_list(['data', 'rgba', 'antialiased'], s=s)
796812
self._interpolation_stage = s
797813
self.stale = True
798814

‎lib/matplotlib/tests/test_image.py

Copy file name to clipboardExpand all lines: lib/matplotlib/tests/test_image.py
+39Lines changed: 39 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1462,6 +1462,45 @@ def test_rgba_antialias():
14621462
cmap=cmap, vmin=-1.2, vmax=1.2)
14631463

14641464

1465+
@check_figures_equal(extensions=('png', ))
1466+
def test_upsample_interpolation_stage(fig_test, fig_ref):
1467+
"""
1468+
Show that interpolation_stage='antialiased' gives the same as 'data'
1469+
for upsampling.
1470+
"""
1471+
# Fixing random state for reproducibility. This non-standard seed
1472+
# gives red splotches for 'rgba'.
1473+
np.random.seed(19680801+9)
1474+
1475+
grid = np.random.rand(4, 4)
1476+
ax = fig_ref.subplots()
1477+
ax.imshow(grid, interpolation='bilinear', cmap='viridis',
1478+
interpolation_stage='data')
1479+
1480+
ax = fig_test.subplots()
1481+
ax.imshow(grid, interpolation='bilinear', cmap='viridis',
1482+
interpolation_stage='antialiased')
1483+
1484+
1485+
@check_figures_equal(extensions=('png', ))
1486+
def test_downsample_interpolation_stage(fig_test, fig_ref):
1487+
"""
1488+
Show that interpolation_stage='antialiased' gives the same as 'rgba'
1489+
for downsampling.
1490+
"""
1491+
# Fixing random state for reproducibility
1492+
np.random.seed(19680801)
1493+
1494+
grid = np.random.rand(4000, 4000)
1495+
ax = fig_ref.subplots()
1496+
ax.imshow(grid, interpolation='antialiased', cmap='viridis',
1497+
interpolation_stage='rgba')
1498+
1499+
ax = fig_test.subplots()
1500+
ax.imshow(grid, interpolation='antialiased', cmap='viridis',
1501+
interpolation_stage='antialiased')
1502+
1503+
14651504
def test_rc_interpolation_stage():
14661505
for val in ["data", "rgba"]:
14671506
with mpl.rc_context({"image.interpolation_stage": val}):

0 commit comments

Comments
0 (0)
Morty Proxy This is a proxified and sanitized view of the page, visit original site.