Abstract

Currently, digital images in the format Full HD (1920 * 1080 pixels) and 4K (4096 * 3072) are widespread. This article will consider the option of processing a similar image in the frequency domain. As an example, take a snapshot of the earth's surface. The discrete Fourier transform will be computed using a two-dimensional analogue of the Cooley-Tukey algorithm and in a standard way by rows and columns. Let us compare the required number of operations and the results of a numerical experiment. Consider the examples of image filtering.

Highlights

  • Digital images in the format Full HD (1920 * 1080 pixels) and 4K (4096 * 3072) are widespread

  • We consider the possibility of using an alternative method - the frequency filtering of such images by calculating the two-dimensional discrete Fourier transform of the function of the brightness of the pixels of the image, applying a filter, and computing the inverse Fourier transform [2]

  • One way to simplify the calculations is to use the classical algorithm for computing the two-dimensional fast Fourier transform (FFT): first, the one-dimensional FFT using the Cooley-Tukey algorithm for each row consisting of 4096 elements is calculated, and the discrete Fourier transform for each column of 3072 elements

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Summary

Introduction

Digital images in the format Full HD (1920 * 1080 pixels) and 4K (4096 * 3072) are widespread. One way to simplify the calculations is to use the classical algorithm for computing the two-dimensional fast Fourier transform (FFT): first, the one-dimensional FFT using the Cooley-Tukey algorithm for each row consisting of 4096 elements is calculated, and the discrete Fourier transform for each column of 3072 elements. In this case, 18*222 + 9*232 = 9234*222 ≈ 9*232 operations of multiplication and 72*222 + 9*232 = 9288*222 ≈ 9*232 addition of complex numbers are required.

Application of a two-dimensional analogue of the CooleyTukey algorithm
Image filtering
Conclusion
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