Most Popular
1500 questions
6
votes
3 answers
Can deep learning be applied to video compression?
H.265 is based on incremental gains over time. The paradigms have largely remained the same. What are the odds of deep learning providing huge performance gains? Here is the main metric:
Perceptual quality remains the same at 2x improvement in…
jkschin
- 163
- 1
- 6
6
votes
1 answer
What is the tightest known bound on the reconstruction error in compressed sensing?
I am specifically thinking about the reconstruction error of L1-minimization from compressed measurements with noise.
I know a bound from (8) in The restricted isometry property and its implications for compressed sensing, but I was wondering if…
Thomas Arildsen
- 1,242
- 7
- 16
6
votes
4 answers
Difference between Contrast and Intensity of an Image
I wanted to generate Gray Scale wedge image of 10 Levels in MATLAB and then increase and decrease its Intensity. By high intensity, I mean mapping increasing the level of gray scale intensity in an image from lower value to higher values.
The…
Sufiyan Ghori
- 2,065
- 11
- 32
- 49
6
votes
2 answers
Deriving the Matrix Inversion Lemma for RLS Equations vs the Woodbury Derivation
Can any one help me in deriving the matrix inversion lemma rule for RLS algorithm?
I don't know how to start with. Many books have just stated but they haven't derived it.
Abhi
- 73
- 5
6
votes
4 answers
How to calculate a delay (correlation peak) between two signals with a precision smaller than the sampling period?
I would like to calculate a delay between two signals in MATLAB. Normally, I would do this with a cross-correlation (xcorr), and then calculate the position of the correlation peak, but in this case I know that the delay is smaller than one sampling…
BNJMNDDNN
- 215
- 2
- 6
6
votes
2 answers
How does zero-padding affect the magnitude of the DFT?
Let's simulate sinusoids of two frequencies using the following Matlab code:
fs = 1000;
t = 0 : 1/fs : 1 - 1/fs;
f1 = 3; f2 = 3.5;
x1 = cos(2*pi*f1*t);
x2 = cos(2*pi*f2*t);
L1 = length(x1); L2 = length(x2);
If I take the FFT of the first signal…
Vivek Subramanian
- 183
- 1
- 1
- 5
6
votes
1 answer
How to derive $r(t) = c(t) \circledast \frac{1}{2} h_b(t, \tau)$?
Consider a linear time-variant channel. The transmitted signal is $x(t)$, the channel impulse response is $h(t, \tau)$, and the received signal is $y(t)$. Then
$$ y(t) = \int_{-\infty}^\infty x(\tau) h(t, \tau) d\tau = x(t) \circledast h(t, \tau),…
Wei-Cheng Liu
- 163
- 5
6
votes
3 answers
RMS calculation in frequency domain after windowing
I can calculate RMS in frequency domain as derived from Parseval's Theorem.
But what if I have applied a windowing function before doing the FFT (in my case a Hann window)?. Now the RMS values are not correct any more. How do I calculate the correct…
venkibabu
- 75
- 2
- 4
6
votes
1 answer
Difference between Gaussian and moving average filters for peak detection and doppler shift detection?
Consider having a signal in the time domain, and you want to smooth the signal. Moving average and Gaussian filters that are used. How do you choose which is used for what?
What are the conditions under which Gaussian is better and conditions under…
Dinesh
- 171
- 1
- 5
6
votes
1 answer
2D Fourier Transform of Rotated Discrete Domain Signal
Assume we know that the Fourier transform of a signal $x(n_1,n_2)$ is $\mathcal{F}(x(n_1,n_2))=X(\omega_1,\omega_2)$. What is the Fourier transform of the signal after being transformed by a rotation matrix?
I have found a property of the DFT that…
Josh
- 167
- 1
- 7
6
votes
2 answers
Random Noise Removal In Images
I'm trying to remove random noise from an image. The noise is arbitrarily random so it must not necessarily follow a certain distribution (Not every pixel has the same chance of being affected by noise and not every pixel is affected by the same…
mroman
- 161
- 1
- 4
6
votes
2 answers
Least Squares with Non Zero Mean Noise
What happens if the noise has no zero mean? I mean, if the exercise is something like:
$$y(k) = A x + \eta(k)$$
When I have zero mean, I start from:
$$y = A x$$
$$\Rightarrow \hat{y} = A \hat{x}$$
Using algebra, I to get to this equation:
$$A^H y =…
Euler
- 173
- 1
- 6
6
votes
1 answer
Adding Salt n Pepper noise into an Image manually
When i looked in to the algorithm of Salt n Pepper noise in a Matlab i've found this,
case 'salt & pepper' % Salt & pepper noise
b = a;
x = rand(sizeA);
d = find(x < p3/2);
b(d) = 0; % Minimum value
d = find(x >= p3/2 & x < p3);
…
Sufiyan Ghori
- 2,065
- 11
- 32
- 49
6
votes
2 answers
breaking the input signal into segments while calculating DFT
Im reading a book about DSP and there is an example about investigating the sound that travel through the ocean. The sound was recorded as the time-domain signal and they tried to analyze it in frequency domain.
The input signal was broke up into…
Mai
- 189
- 1
- 4
- 9
6
votes
2 answers
What should be the correct scaling for PSD calculation using $\tt fft$
I would to calculate the PSD of a signal using FFT however the result do not match with periodogram command. What did was as follow…
justin
- 159
- 1
- 11