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"__type": "Text", "__tag": 4046, "value": "Here's a simple FFT-based lowpass filter applied to an image of white noise.\n\nThis code will generate an image of white noise, use `rfft2` to transform\nit to the frequency domain, apply a lowpass filter, and then transform back\nto the spatial domain with `irfft2`.\n\n" }, { "__type": "Code", "__tag": 4050, "value": "import numpy as np\nimport matplotlib.pyplot as plt\nfrom scipy.fft import rfft2, irfft2, fftfreq, rfftfreq\nrng = np.random.default_rng()\nm = 280 # Image size is m x m.\n", "execution_status": "success", "out": "" }, { "__type": "Text", "__tag": 4046, "value": "\nGenerate an image of white noise:\n\n" }, { "__type": "Code", "__tag": 4050, "value": "im = rng.normal(size=(m, m))\n", "execution_status": "success", "out": "" }, { "__type": "Text", "__tag": 4046, "value": "\nTransform to the frequency domain:\n\n" }, { "__type": "Code", "__tag": 4050, "value": "f = rfft2(im)\n", "execution_status": "success", "out": "" }, { 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