12 votes
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Why does the derivative of an audio file act like a high-pass filter?

Yes both the time derivative $d/dt$ and the discrete time difference $x[n]-x[n-1]$ are indeed "high pass filters": consider the extreme case of the lowest frequency, which is DC or a ...
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  • 37.7k
11 votes

Why does the derivative of an audio file act like a high-pass filter?

$\frac{d}{dt}\sin(\omega t) = \omega\cos(\omega t)$ as a consequence of the chain rule. $\sin$ and $\cos$ are the same apart from the phase shift, so the derivative is a filter with a response that's ...
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  • 219
10 votes
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How to produce a high-pass filter from a low-pass one?

The result will indeed be a high pass filter. From your difference equation, the transfer function of the low pass filter is $$H_l(z)=\frac{\beta}{1-(1-\beta)z^{-1}}\tag{1}$$ with $\beta=1/\alpha$. ...
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9 votes
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Is a high-passed signal the same as a signal minus a low-passed signal?

In general you can't simply subtract a low-pass filtered version of a signal from the original one to obtain a high-pass filtered signal. The reason is as follows. What you're actually doing is ...
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9 votes
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Is there an adjective describing a filter with kernel that has zero mean?

"Zero-Mean" is the word that's commonly used to describe signals and signals with a zero average. "This is a zero-mean filter." If you really mean a filter that is specifically ...
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7 votes

Should I Use a High Pass Filter (HPF) or Low Pass Filter (LPF) to Enhance the Features for Image Splicing Detection?

Since you're after a filter which emphasizes abrupt changes you should use High Pass Filter. The issue is you'd be also sensitive to noise. Hence one way to do it is to apply High Pass Filter on ...
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7 votes

Designing High Pass Filter to Remove DC Offset from a Signal

If the DFT is the Uniform sampling from $ 0 $ to $ 2 \pi $ then the first bin is given by: $$ x[k] = \sum_{n = 0}^{N - 1} x[n] $$ Namely it is the sum of all the samples. Hence in order to remove ...
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7 votes
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How is the lowpass to bandpass transformation derived?

In the $s$-domain, the LPF-to-BPF transformation doubles the order of the filter. that is because the LPF has one transition from passband to stopband, but the BPF has two such transitions. Remember ...
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7 votes
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How to Classify a Kernel as Low Pass Filter (LPF) or High Pass Filter (HPF)? How to Transform an LPF Kernel into HPF Kernel?

General We assume 2 modes of filters: LPF or HPF. Classifying Filter Type Usually, if it is a well planned LPF and well Planned HPF a simple test will do. Calculate the sum of all coefficients. The ...
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7 votes
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3 dB cut-off frequency of first-order IIR high-pass filter

A discrete-time first-order high pass filter with unity gain at Nyquist and a zero at DC is described by the following difference equation: $$y[n]=\frac{1+\alpha}{2}\big(x[n]-x[n-1]\big)+\alpha y[n-1],...
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6 votes
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Applying a high-pass filter on constant signal

The input to your filter is essentially a step function (since it has value 0 prior to t = 0, and a positive value for t > 0), so you see the step response of the filter, hence the initial ringing. ...
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6 votes

How to produce a high-pass filter from a low-pass one?

For an LTI system another method to generate a highpass filter impulse response $h_{hp}[n]$, from an existing lowpass filter impulse reponse $h_{lp}[n]$ is the following: $$h_{high}[n]=(-1)^n h_{low}[...
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6 votes

Why does the derivative of an audio file act like a high-pass filter?

@OverLordGoldDragon Your x(n)−x(n−1) expression is called a "first-difference discrete differentiator". Its frequency magnitude response is the blue dashed curve below:
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5 votes
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How to Classify Image Filter as Low Pass Filter (LPF) or High Pass Filter (HPF)?

Welcome to DSP Community. General We assume 2 types of filters: LPF or HPF. Classifying Filter Type Usually, if it is a well planned LPF and well Planned HPF a simple test will do. Calculate the ...
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5 votes

Is the Sobel filter a high pass filter, and if not, what is the difference between them?

They are both highpass type filters, but used with very different intentions. One should immediately observe the fundamental difference that the output of unsharp masking filter is an enhanced image ...
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5 votes

Calculating the 3dB frequency of an nth order low pass filter and nth order high pass filter

In general there is no straightforward analytical solution. As you know, you need to solve $$\left|H(e^{j\omega_c})\right|=\frac{1}{\sqrt{2}}\tag{1}$$ for $\omega_c$, where it is assumed that the ...
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5 votes
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Is the Laplacian Filter an High Pass Filter (HPF)?

There are many approximations for the Laplacian Filter (See The Hypermedia Image Processing Reference - Laplacian/Laplacian of Gaussian): Indeed this is an High Pass Filter (HPF). Namely it will ...
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4 votes
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Removal of noise from vibration recordings

If you want to detect the peak value of the time-domain signal, it is important not to change phase of each frequency signals. Otherwise, the peak value will be affected by it and will slightly change....
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  • 66
4 votes
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What is the name of the following 1st order high-pass IIR filter?

This is a first-order discrete-time Butterworth filter, which can be obtained via the bilinear transform from the following analog prototype filter (with normalized cut-off frequency): $$H(s)=\frac{s}...
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4 votes

High / Low Pass Filters from Zero

I will try to be intuitive more than rigorous. Low Pass Filter means a filter which limits the ability of the output data to change fast (Relative to a parameter called the Low Pass Cut Off Frequency)....
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4 votes
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High / Low Pass Filters from Zero

"Low pass" is a qualifier. I can recall maybe more then 5 low pass qualities but each bringing along a different phase response making it attractive to a particular application. Others may be able to ...
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4 votes
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Poles and zeros map

Note that the pole locations would be the same for all $4$ classic types of frequency-selective filters (low pass, high pass, band pass, band stop). It's the location of the zeros that determines ...
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4 votes
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How to detect and distinguish oscillations in a signal?

If your signal is a narrow band and real signal, the Hilbert Transform can be useful to determine the amplitude modulation and phase modulation components of the signal. This is done by adding the ...
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4 votes

Why does the derivative of an audio file act like a high-pass filter?

You're doing $x(n) - x(n - 1)$, the finite difference / "discrete derivative", not to be confused with $\frac{d}{dt}x(t)$. The frequency response is where $H(\omega) = 1 - e^{-j 1\omega}$ ...
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3 votes

High-pass filtering pre-processing before computing audio features

I agree that a large-order (12 taps+) high-pass Butterworth filter will be sufficient. Why? Well, Butterworth filters are commonly used in professional audio-editing applications to do filtering, ...
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3 votes

Is a high-passed signal the same as a signal minus a low-passed signal?

Regarding scaling: If you sum up the coefficients, you get the magnitude for DC. Hence, it makes sense that you get those numbers ($\approx 1$ for LP, $\approx 0$ for HP). In addition to Matt L.'s ...
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3 votes

How to convert a low-pass Gaussian filter to a high pass filter

The simplest option is to remove the low-pass signal from the data. Just subtract the outcome of your code from the original image. This amounts to computing: $$I_\textrm{high} = \delta \ast I - g\...
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3 votes

What is the name of these simple filter algorithms?

out[i] = out[i-1] + (alpha*(in[i] - out[i-1])); From Wikipedia's article on Low pass filters: That is, this discrete-time implementation of a simple RC low-...
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3 votes
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What is the name of these simple filter algorithms?

In addition to @MarcusMüller answer, you can find other names and historical details on this type of filter in Is there a technical term for this simple method of smoothing out a signal?. I will not ...
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