November 2018
Intermediate to advanced
492 pages
12h 19m
English
Content preview from Hands-On Image Processing with Python
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Plotting the histograms of pixel values for the RGB channels of an image
The histogram() function can be used to compute the histogram (a table of pixel values versus frequencies) of pixels for each channel and return the concatenated output (for example, for an RGB image, the output contains 3 x 256 = 768 values):
pl = im.histogram()plt.bar(range(256), pl[:256], color='r', alpha=0.5)plt.bar(range(256), pl[256:2*256], color='g', alpha=0.4)plt.bar(range(256), pl[2*256:], color='b', alpha=0.3)plt.show()
The following figure shows the R, G, and B color histograms plotted by running the previous code:
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