Questions tagged [distortion]
The distortion tag has no usage guidance.
61
questions
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12 views
How does image rotation affect the intrinsic camera parameters?
I am considering the problem of how to (manually) change camera model parameter to make it "valid" on a rotated image. This question tackles resizing, but does not consider lens distortion.
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2
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1answer
54 views
Exponential Swept Sine Distortion
I was able to get passable results on fundamental measurements using and exponential swept sine. Now I am trying to get distortion information from the same measurement but am puzzled by the results. ...
1
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1answer
24 views
Signal distortion under non-linear channel
The channel is given to have these characteristics, and its required to study the affect on Frequency Modulated signal and its demodulation.
Since there are no sharp corners (like during clipping) ...
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1answer
61 views
What function to apply a Metamorphopsia (grid warp) translation?
How would I go about finding or creating a function to warp images dependent on grid lines surrounding an origin (I don't wish for a grid on my actual images):
It should work in practically the same ...
0
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1answer
46 views
Understanding legacy code: Algorithm to remove radial lens distortion
The method below to remove lens distortion from a camera was written more than ten years ago and I am trying to understand how the approximation works.
...
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0answers
13 views
Overlaying A Distorted Text According to its Background
I have several dirty background images, sample image is below:
I want to overlay a text on it but I want the text to be as distorted as the background. Example, if the background is a bit wavy, I ...
0
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1answer
45 views
Total Harmonic Distortion THD for the rectifier
I have a circuit with rectifier and this cause the non-linearity and consequently harmonic. I show it on the oscilloscope and then collect the signal from the oscilloscope to the computer by using the ...
4
votes
1answer
146 views
Group Delay for Hilbert Transformer and Resulting Dispersion
An ideal Hilbert Transformer shifts the phase for all positive frequencies by $-\pi/2$ and all negative frequencies by $+\pi/2$ while maintaining constant magnitude everywhere. Group Delay is the ...
0
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1answer
45 views
How to quantify phase distortion of a filter specific to a signal?
For example, a EKG input signal is filtered with a known transfer function that does not have linear phase. How do you quantify the phase distortion of the output signal given you have the input? I ...
0
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1answer
230 views
How to prevent distortion after down-sampling?
I am new to audio signal processing, but in one of my machine learning projects that I am working on, I need to down-sample my audio somewhere in the middle of my neural network. Therefore, I need a ...
0
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0answers
560 views
How to measure SINAD of an audio signal?
I tried to measure the SINAD and SNR of a recorded audio signal using MATLAB. The following is the process I did to measure the 2 parameters:
Firstly, I generated an FM modulated signal(1 kHz audio ...
2
votes
1answer
109 views
Distort voice to hide talker identity as much as possible
I need to develop an app which makes speech recognition. Because I need to be able to constantly improve the recognition capability, I would like to train the engine with real recordings and match the ...
0
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1answer
93 views
Recommendations for SINAD equipment
I am interested in buying a device that measures the SINAD of the audio signal(FM signal) that I receive from PC.
Here is the setup:
Signal generator (generating 1kHz FM signal ) $\rightarrow$ ...
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0answers
21 views
Any recommendations for buying SINAD measuring equipment? [duplicate]
I am interested in buying a device that measures the SINAD of the audio signal(FM signal) that I receive from PC. Here is the setup :
Signal generator -> attenuator ->HackRF connected to PC with SDR#
...
0
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1answer
123 views
Linear vs Non linear distortion
I'm learning about distortion and I got stuck at
"What is the difference between linear and non-linear distortion?"
(Also in frequency spectrum i.e. Amplitude and phase spectrum)
4
votes
3answers
526 views
Precise 5th and 7th harmonics of a sampled sine wave
Does anyone know in decibels (to 1/100th of a dB) what the theoretical 3rd, 5th and 7th harmonic of a 0dB fs 24-bit (i.e. full-level; 0dB = -8,388,607 to 8,388,607) sampled sine wave without dither ...
0
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1answer
248 views
Can I use SINAD for THD+N measurements? Are they inverse of each other?
I'm looking for a clarification, which I haven't really been able to find. It's probably obvious but I'd like to be absolutely sure of what I'm calculating.
I noticed that the formula that calculates ...
0
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2answers
54 views
Audio sounds oddly distorted [closed]
https://clips.twitch.tv/TangentialObliqueLobsterSaltBae
https://clips.twitch.tv/CharmingBashfulAlfalfaRickroll
https://clips.twitch.tv/NaiveKindGorillaGivePLZ
(Disclaimer: These were not recorded on ...
0
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1answer
100 views
Finding the memory polynomial model coefficients
I want to build a memory polynomial model given that I know the corresponding output signals for known input signals.
What is the easiest way to find the coefficients of it?
And how do we take the ...
0
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1answer
276 views
Dithering adds harmonic distortion after filtering and upsampling
I have an issue which I wasn't able to solve for a few days. I have implemented a polyphase FIR interpolation filter within an FPGA which does interpolate by a factor of 8 or 16 times. I do accept an ...
0
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2answers
83 views
Why is distorted / quantized white noise still white noise?
White noise can be created by setting every sample in the time domain to a random number with a gaussian distribution. Every sample is random, so the frequency response is obviously random. Easy ...
1
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1answer
294 views
Identify the Type of Image Distortion (On Lena Image)
I want to understand the distortions in each of the lena images shown in the image below.
I see that the first one is a blur. How can undo the blur. The second one is colored salt and pepper noise. ...
0
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1answer
56 views
THD requirement for generated sine
I need to generate a sine signal using a DAC with a certain THD specification, say 0.1% @ 1KHz. As a first approach I’m considering it to be an ideal DAC along with an ideal LPF for aliasing removal ...
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1answer
239 views
Redistributing Color in a RGB Image According to a Gaussian Distribution
I haven't done this stuff in a while.
If I have an image $I$ I can equalize the histogram of the image using some opencv procedure, it's already defined. Equalizing an histogram means essentially to ...
3
votes
1answer
533 views
Can someone explain waveshaping to me?
Can someone explain waveshaping to me?
I only know it shapes waveshapes by passing through some functions, but I don't yet understand e.g. what the plots (such as the following in Melda Production ...
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0answers
92 views
Calculating Transfer Functions From Harmonic Distortion Percentage
Hi I am working on emulating a piece of analog audio equipment and would like to be able to create a transfer function based on the measured percentages of harmonic distortion.
I know that harmonic ...
2
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0answers
100 views
Wave Shaper Function From A Waveshaped Singal
Is there a way to work out an unknown waveshaper function, that was used to distort and map the values of an input signal to new output signal, form the output if we only have input signal and the ...
2
votes
1answer
368 views
Norm MPEG-1 Layer III (Mp3) Filter banks distortion
So, I'm working with the filter banks used in Mp3, in Matlab. I am obtaining quite a huge distortion in the output and I don't really know whether I'm making something wrong.
I've reviewed the ...
3
votes
2answers
469 views
Digital modelling of circuits with diode (i.e. guitar distortion)
For the last few days I was struggling to come up with an idea how to model a guitar overdrive effect which works in realtime. One of the simplest circuit diagrams that produce it looks as follows:
...
3
votes
1answer
162 views
Spectral baseline distortion simulation - Bruker smile
I work with Magnetic Resonance Spectroscopy data. Data (complex signals) obtained from Bruker scanners (one of the biggest manufacturers of MRS scanners) start with an important group delay - around ...
2
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0answers
449 views
Demodulation distortion in single-sideband and double-sideband
I am trying to compare the demodulation for single sideband (SSB) and dual sideband modulation formats (DSB) when the reconstructed carrier is not perfect (i.e. shifted in both frequency and phase). I ...
2
votes
1answer
250 views
Regarding the advantages of generalized linear phase filters
I know that for a linear-phase filter with frequency response given by
$$H(e^{j\omega}) = |H(e^{j\omega})|e^{j\phi(\omega)} $$
if the input of the system is
$$x[n] = s[n]\cos[\omega_0 n] $$
where $s[...
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1answer
73 views
Can IR emitter signal be distorted by curved glass housing around receiver?
I have built a garage door opening circuit that includes an IR sensor and an IR emitter (a remote control). When the IR sensor is in the open air it works fine.
If I put the sensor inside a glass ...
1
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1answer
192 views
Create distortion from basic linear (and non-linear if neccessary) DSP elements
I'm studying mechatronics and I'm intrested in DSP basics. My lecturer said that there are four basic linear DSP elements:
Adder (and other mathematical operations)
Amplification (shown on diagrams ...
0
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1answer
1k views
If a filter has a non-linear phase lag will the output signal be distorted?
EDIT: From here (https://www.mathworks.com/help/signal/ref/butter.html)
it appears that an Butterworth filter has a non-linear phase lag at the normalized frequency of 0.5 onwards.
Does that mean that ...
0
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1answer
138 views
Determine modulation function from spectrum?
I have a two periodic signals $x(t)$ and $y(t)$ which are related to each other by a periodic modulation function $\alpha(t)$:
$$y(t) = \alpha(t) x(t)$$
If $x(t)$ is a sinusoid, is it possible to ...
0
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1answer
250 views
How to analyze image quality?
I have a few sequences of images, taken at fixed camera position, that address a moving object, which means the object moves towards the camera. But all the sequences of images are the cropped images ...
0
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1answer
125 views
What is this kind of distortion called?
Today while watching a movie I noticed the following distortion:
Note. The red ring is me painting over to show the area of interest.
There are certain areas in which I can see non-smooth shades of ...
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0answers
1k views
How to estimate THD?
I have a signal source that I can digitise and read. It produces mainly a 50Hz sine wave, but there is distortion as well. I'd like to estimate the total harmonic distortion for this signal. I've ...
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0answers
319 views
how to get an input test signal for convolution/ distortion method
i am trying to do some experiments with Total Harmonic Distortion.
According to ...
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0answers
131 views
FFT Convolution: missing sample somewhere
For a piece of software I've been working on lately I need to implement FFT convolution for performance reasons.
Doing so has been mildly succesfull but there is still a error somewhere causing lots ...
11
votes
1answer
235 views
Quantitative Comparison of Scaled, Delayed and Warped Signals
The following question is detailed in 1D, with time as the ordinal variable. Similar questions could apply in other dimensions.
In several signal processing techniques, such as blind source ...
0
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1answer
306 views
Vinyl Crackling Effect
I want to know how can I achieve this effect:
https://www.youtube.com/watch?v=DQg9M_47c3A
Do I need to use a filter? And what can I use for the crackling, poping effect?
Thanks in advance!
2
votes
1answer
92 views
Distances In a Single Image With Some Real References
Consider following image:
We have some real references here: Stonehenge measurements (stone dimensions and distances), some strait lines at the back of carts, cart wheels that are almost of the same ...
3
votes
2answers
2k views
How to estimate radial distortion from lens characteristics?
Is there a way to estimate the radial distortion coefficients without calibration, given the lens characteristics, such as its diameter and its focal length?
Typically for camera calibration a ...
0
votes
1answer
223 views
Slight crackle with overlap-add frequency-domain convolution
I'm trying to make an FFT audio filter using overlap-add but there's some slight rhythmic distortion/crackle in the output. I have an irSize (impulse response size) of 512 samples and a blockSize of ...
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0answers
347 views
Can sample aliasing of strictly white noise lead to random walk (drift) in the sampled signal?
Aliasing of tones higher than the Nyquist frequency, and where the tone may have some degree of nonlinear distortion can appear as low frequency 'drift' or even near static bias in the sampled signal.
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2answers
232 views
What is done to minimize distortion due to the hold operation?
A hold operation can be modeled using a step function over one sampling period i.e.
$R(t) = 1/T * (h(t) - h(t-T))$, $h(t)$ the step function
In frequency domain this is equivalent to
$R(jw) = e^{-...
1
vote
1answer
409 views
Total Harmonic Distortion calculation and its origins
I ve been researching about harmonic distortion and THD. From what i ve seen on the internet, HD is caused by non-linear signal processing. I want to calculate it using an digital signal processor. ...
-1
votes
1answer
534 views
FFT window corrupts signal
this is a newbie question.
My goal is to create audio filter that cleans human speech from noise. I started with learning all about fft filters. At first I've created simple fft filter with ...
