fft

来源： https://stackoverflow.com/questions/52730753/how-to-get-frequency-axis-from-an-fft-function

来源： https://stackoverflow.com/questions/16720682/pil-cannot-write-mode-f-to-jpeg

来源： https://stackoverflow.com/questions/56791652/1-3-octave-from-audio-file-with-python

问题 According to the convolution theorem, convolution changes to pointwise multiplication in the fourier domain, and the overheads of taking the fourier transform have been shown to be overshadowed by the gain due to conversion of convolution operation to pointwise multiplication operation in many previous works like the following - https://arxiv.org/abs/1312.5851. To replicate this, I was trying to replace the keras.layers.Conv2D() layer by a custom layer that accepts the rfft of input data (I

问题 I'm trying to make sense of the output produced by the python FFT library. I have a sqlite database where I have logged several series of ADC values. Each series consist of 1024 samples taken with a frequency of 1 ms. After importing a dataseries, I normalize it and run int through the fft method. I've included a few plots of the original signal compared to the FFT output. import sqlite3 import struct import numpy as np from matplotlib import pyplot as plt import time import math conn =

问题 I am trying to make a program in python which will take in sound frequencies with pyaudio and show ranges of frequencies as bars going up and down using turtle. I want it to look something like this: I followed this tutorial for getting and graphing the sound data in an fft format: https://www.youtube.com/watch?v=aQKX3mrDFoY My code is formatted to have 32 eq bands. To split the frequencies into 32 groups, I loop through the frequency list created by pyaudio and add all of the values of the

问题 I'm experimenting with KISSFFT in C++ after being discouraged to use FFTPACK to process 2D arrays. I wrote an element-wise multiplication function to multiply two 2D arrays after they've been transformed with kiss_fftnd() . The result of the multiplication is then transformed back with the inverse FFT function. Unfortunately, the results I get from kissfft in C are different from what I get with SciPy in python as you can see in the image below: To test the multiplication function, after the

问题 I'm having trouble getting the phase of a simple sine curve using the scipy fft module in python. I followed this tutorial closely and converted the matlab code to python. However, no matter what phase I use for the input, the graph always shows 3. What am I missing? import numpy as np import matplotlib.pyplot as plt import scipy.fftpack import cmath A=10 fc = 10 phase=60 fs=32#Sampling frequency with oversampling factor of 32 t = np.arange(0,2,1/fs) #Convert the phase shift to radians from

问题 I'm having trouble getting the phase of a simple sine curve using the scipy fft module in python. I followed this tutorial closely and converted the matlab code to python. However, no matter what phase I use for the input, the graph always shows 3. What am I missing? import numpy as np import matplotlib.pyplot as plt import scipy.fftpack import cmath A=10 fc = 10 phase=60 fs=32#Sampling frequency with oversampling factor of 32 t = np.arange(0,2,1/fs) #Convert the phase shift to radians from

问题 Image Loading To start I tried loading in .tif images using openCV but got the following error: Invalid bitsperpixel value read from TIFF header! Must be 1, 8, 16, 32 or 64. in function 'cv::TiffDecoder::readHeader' Checked using a hex editor to determine the bit depth of the image and it seems to be 16bit. After some trail and error I managed to find a solution using the code below. First loaded the image with the specialized tifffile library. Then saved it to a temporary file and finally