# Tag Info

Accepted

### 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 ...
• 37.7k

### 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 ...
• 219
Accepted

### 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 $\beta=1/\alpha$. ...
• 80.4k
Accepted

### 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 ...
• 80.4k
Accepted

### 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 ...
• 26.6k

### 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 ...
• 41.4k

### 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 ...
• 41.4k
Accepted

### 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 ...
Accepted

### 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 ...
• 41.4k
Accepted

• 26.8k

### 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:
• 4,898
Accepted

### 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 ...
• 41.4k

### 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 ...
• 26.8k

### 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 ...
• 80.4k
Accepted

### 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 ...
• 41.4k
Accepted

### 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....
• 66
Accepted

• 30.2k

### 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-...
• 26.6k