DOC: Rename equalize example to match function name.

doc/examples/plot_equalize.py

@@ -0,0 +1,54 @@
+"""
+======================
+Histogram Equalization
+======================
+
+This examples takes an image with low contrast and enhances its contrast using
+histogram equalization. Histogram equalization enhances contrast by "spreading
+out the most frequent intensity values" in an image [1]_. The equalized image
+has a roughly linear cumulative distribution function, as shown in this example.
+
+.. [1] http://en.wikipedia.org/wiki/Histogram_equalization
+
+"""
+import matplotlib.pyplot as plt
+
+from skimage import data
+from skimage.util.dtype import dtype_range
+from skimage import exposure
+
+
+def plot_hist(img, bins=256):
+    """Plot histogram and cumulative histogram for image"""
+    img_cdf, bins = exposure.cumulative_distribution(img, bins)
+    plt.hist(img.ravel(), bins=bins)
+    ax_cdf = plt.twinx()
+    ax_cdf.plot(bins, img_cdf, 'r')
+    xmin, xmax = dtype_range[img.dtype.type]
+    plt.xlim(xmin, xmax)
+
+    plt.ylabel('# pixels')
+    plt.xlabel('pixel intensiy')
+    ax_cdf.set_ylabel('fraction of total intensity')
+
+
+img_orig = data.camera()
+# squeeze image intensities to lower image contrast
+img = img_orig / 5 + 100
+img_eq = exposure.equalize(img)
+
+plt.subplot(2, 2, 1)
+plt.imshow(img, cmap=plt.cm.gray, vmin=0, vmax=255)
+plt.axis('off')
+plt.subplot(2, 2, 2)
+plot_hist(img)
+
+plt.subplot(2, 2, 3)
+plt.imshow(img_eq, cmap=plt.cm.gray, vmin=0, vmax=1)
+plt.axis('off')
+plt.subplot(2, 2, 4)
+plot_hist(img_eq)
+
+plt.subplots_adjust(left=0.05, hspace=0.25, wspace=0.3, top=0.95, bottom=0.1)
+plt.show()
+