Doxygen tutorials: python final edits
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@@ -5,7 +5,7 @@ Goal
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----
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In this section, we will learn
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- To find the Fourier Transform of images using OpenCV
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- To find the Fourier Transform of images using OpenCV
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- To utilize the FFT functions available in Numpy
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- Some applications of Fourier Transform
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- We will see following functions : **cv2.dft()**, **cv2.idft()** etc
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@@ -134,11 +134,14 @@ plt.subplot(122),plt.imshow(magnitude_spectrum, cmap = 'gray')
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plt.title('Magnitude Spectrum'), plt.xticks([]), plt.yticks([])
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plt.show()
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@endcode
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@note You can also use **cv2.cartToPolar()** which returns both magnitude and phase in a single shot
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So, now we have to do inverse DFT. In previous session, we created a HPF, this time we will see how
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to remove high frequency contents in the image, ie we apply LPF to image. It actually blurs the
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image. For this, we create a mask first with high value (1) at low frequencies, ie we pass the LF
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content, and 0 at HF region.
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@code{.py}
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rows, cols = img.shape
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crow,ccol = rows/2 , cols/2
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@@ -165,7 +168,10 @@ See the result:
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@note As usual, OpenCV functions **cv2.dft()** and **cv2.idft()** are faster than Numpy
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counterparts. But Numpy functions are more user-friendly. For more details about performance issues,
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see below section. Performance Optimization of DFT ==================================
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see below section.
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Performance Optimization of DFT
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===============================
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Performance of DFT calculation is better for some array size. It is fastest when array size is power
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of two. The arrays whose size is a product of 2’s, 3’s, and 5’s are also processed quite
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