Revision: 8300
http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8300&view=rev
Author: mdboom
Date: 2010-05-06 19:59:32 +0000 (Thu, 06 May 2010)
Log Message:
-----------
Save DPI metadata to the file produced by imsave(). Defaults to 100 dpi (for
lack of a better default)
Modified Paths:
--------------
trunk/matplotlib/lib/matplotlib/image.py
trunk/matplotlib/lib/matplotlib/tests/test_image.py
Modified: trunk/matplotlib/lib/matplotlib/image.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/image.py 2010-05-06 19:14:11 UTC (rev
8299)
+++ trunk/matplotlib/lib/matplotlib/image.py 2010-05-06 19:59:32 UTC (rev
8300)
@@ -1113,7 +1113,8 @@
return handler(fname)
-def imsave(fname, arr, vmin=None, vmax=None, cmap=None, format=None,
origin=None):
+def imsave(fname, arr, vmin=None, vmax=None, cmap=None, format=None,
+ origin=None, dpi=100):
"""
Saves a 2D :class:`numpy.array` as an image with one pixel per element.
The output formats available depend on the backend being used.
@@ -1140,14 +1141,18 @@
[ 'upper' | 'lower' ] Indicates where the [0,0] index of
the array is in the upper left or lower left corner of
the axes. Defaults to the rc image.origin value.
+ *dpi*
+ The DPI to store in the metadata of the file. This does not affect the
+ resolution of the output image.
"""
from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
from matplotlib.figure import Figure
- fig = Figure(figsize=arr.shape[::-1], dpi=1, frameon=False)
+ figsize = [x / float(dpi) for x in arr.shape]
+ fig = Figure(figsize=figsize, dpi=dpi, frameon=False)
canvas = FigureCanvas(fig)
- fig.figimage(arr, cmap=cmap, vmin=vmin, vmax=vmax, origin=origin)
- fig.savefig(fname, dpi=1, format=format)
+ im = fig.figimage(arr, cmap=cmap, vmin=vmin, vmax=vmax, origin=origin)
+ fig.savefig(fname, dpi=dpi, format=format)
def pil_to_array( pilImage ):
Modified: trunk/matplotlib/lib/matplotlib/tests/test_image.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/tests/test_image.py 2010-05-06 19:14:11 UTC
(rev 8299)
+++ trunk/matplotlib/lib/matplotlib/tests/test_image.py 2010-05-06 19:59:32 UTC
(rev 8300)
@@ -3,6 +3,7 @@
from matplotlib.testing.decorators import image_comparison, knownfailureif
import matplotlib.pyplot as plt
from nose.tools import assert_raises
+from numpy.testing import assert_array_equal
import cStringIO
import os
@@ -66,6 +67,35 @@
# plt.imread(fname)
# os.remove(fname)
+def test_imsave():
+ # The goal here is that the user can specify an output logical DPI
+ # for the image, but this will not actually add any extra pixels
+ # to the image, it will merely be used for metadata purposes.
+
+ # So we do the traditional case (dpi == 1), and the new case (dpi
+ # == 100) and read the resulting PNG files back in and make sure
+ # the data is 100% identical.
+ from numpy import random
+ random.seed(1)
+ data = random.rand(256, 256)
+
+ buff_dpi1 = cStringIO.StringIO()
+ plt.imsave(buff_dpi1, data, dpi=1)
+ plt.imsave("test_dpi1.png", data, dpi=1)
+
+ buff_dpi100 = cStringIO.StringIO()
+ plt.imsave(buff_dpi100, data, dpi=100)
+ plt.imsave("test_dpi100.png", data, dpi=1)
+
+ buff_dpi1.seek(0)
+ arr_dpi1 = plt.imread(buff_dpi1)
+
+ buff_dpi100.seek(0)
+ arr_dpi100 = plt.imread(buff_dpi100)
+
+ assert_array_equal(arr_dpi1, arr_dpi100)
+
+
if __name__=='__main__':
import nose
nose.runmodule(argv=['-s','--with-doctest'], exit=False)
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