November 2018
Intermediate to advanced
492 pages
12h 19m
English
Content preview from Hands-On Image Processing with Python
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Using a notch filter to remove periodic noise from images
In this example, we will first add some periodic (sinusoidal) noise to the parrot image to create a noisy parrot image (this can happen because of interference with some electrical signal) and then observe the effect of the noise in the frequency domain of the image using the following code block:
from scipy import fftpackpylab.figure(figsize=(15,10))im = np.mean(imread("../images/parrot.png"), axis=2) / 255print(im.shape)pylab.subplot(2,2,1), pylab.imshow(im, cmap='gray'), pylab.axis('off')pylab.title('Original Image')F1 = fftpack.fft2((im).astype(float))F2 = fftpack.fftshift( F1 )pylab.subplot(2,2,2), pylab.imshow( (20*np.log10( 0.1 + F2)).astype(int), cmap=pylab.cm.gray)pylab.xticks(np.arange(0, ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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