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compare local and global equalise in example

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Olivier Debeir
2012-10-29 18:07:47 +01:00
parent d13517035f
commit dc838a690f
1 changed files with 7 additions and 6 deletions
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doc/examples/plot_local_equalize.py
+7 -6
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@@ -5,13 +5,14 @@ Local Histogram Equalization
This examples enhances an image with low contrast, using a method called
*local histogram equalization*, which "spreads out the most frequent intensity
values" in an image . The equalized image has a roughly linear cumulative
distribution function for each pixel neigborhood.
values" in an image . The equalized image [1]_ has a roughly linear cumulative
distribution function for each pixel neighborhood. The local version [2]_ of the histogram
equalization emphasized every local graylevel variations.
to be adjusted...
.. [1] http://en.wikipedia.org/wiki/Histogram_equalization
.. [2] http://homepages.inf.ed.ac.uk/rbf/HIPR2/stretch.htm
.. [2] http://en.wikipedia.org/wiki/Adaptive_histogram_equalization
"""
@@ -58,7 +59,7 @@ img = data.moon()
# Contrast stretching
p2 = np.percentile(img, 2)
p98 = np.percentile(img, 98)
img_rescale = exposure.rescale_intensity(img, in_range=(p2, p98))
img_rescale = exposure.equalize(img)
# Equalization
selem = disk(30)
@@ -73,10 +74,10 @@ ax_img.set_title('Low contrast image')
ax_hist.set_ylabel('Number of pixels')
ax_img, ax_hist, ax_cdf = plot_img_and_hist(img_rescale, axes[:, 1])
ax_img.set_title('Contrast stretching')
ax_img.set_title('Global equalise')
ax_img, ax_hist, ax_cdf = plot_img_and_hist(img_eq, axes[:, 2])
ax_img.set_title('Local Histogram equalization')
ax_img.set_title('Local equalize')
ax_cdf.set_ylabel('Fraction of total intensity')