Work in progress, new examples

Author: jesolem

examples2/ch1_image_representation.py

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+from PIL import Image
+import numpy as np
+import matplotlib.pyplot as pl
+
+"""
+This example shows how images are represented using pixels, color channels and data types.
+"""
+
+
+# read image to array
+im = np.array(Image.open('../data/empire.jpg'))
+print("Shape is: {0} of type {1}".format(im.shape, im.dtype))
+
+# read grayscale version to float array
+im = np.array(Image.open('../data/empire.jpg').convert('L'),'f')
+print("Shape is: {0} of type {1}".format(im.shape, im.dtype))
+
+# visualize the pixel value of a small region
+col_1, col_2 = 190, 225
+row_1, row_2 = 230, 265
+
+# crop using array slicing
+crop = im[col_1:col_2,row_1:row_2]
+cols, rows = crop.shape
+
+print("Created crop of shape: {0}".format(crop.shape))
+
+# generate all the plots
+pl.figure()
+pl.imshow(im)
+pl.gray()
+pl.plot([row_1, row_2, row_2, row_1, row_1], [col_1, col_1, col_2, col_2, col_1], linewidth=2)
+pl.axis('off')
+
+pl.figure()
+pl.imshow(crop)
+pl.gray()
+pl.axis('off')
+
+pl.figure()
+pl.imshow(crop)
+pl.gray()
+pl.plot(20*np.ones(cols), linewidth=2)
+pl.axis('off')
+
+pl.figure()
+pl.plot(crop[20,:])
+pl.ylabel("Graylevel value")
+
+from mpl_toolkits.mplot3d import axes3d
+fig = pl.figure()
+ax = fig.gca(projection='3d')
+# surface plot with transparency 0.5
+X,Y = np.meshgrid(np.arange(cols),-np.arange(rows)) 
+ax.plot_surface(X, Y, crop, alpha=0.5, cstride=2, rstride=2)
+
+pl.show()

examples2/examples.md

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+## Exemples for the upcoming edition of PCV
+
+This folder contains work in progress and files intended for the second edition of "Programming Computer Vision with Python".
+
+More details on the book can be found at [programmingcomputervision.com](http://programmingcomputervision.com/)