Signal Processing Weekly Newsletter

Signal Processing newsletter

Top new questions this week:

Bicubic Interpolation

I'm trying to do bicubic interpolation on an 8*8 matrix(image) shown below. A = 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 10 20 …

image-processing matlab interpolation  
asked by Celine 2 votes
answered by nivag 1 vote

How is a realtime BiQuad/IIR possible?

I was thinking, if a realtime system is one in which the processing time is shorter than the sampling period, how does a feedback filter such as a biquad perform the computation without waiting for, …

real-time biquad  
asked by Anthony Parks 2 votes
answered by SleuthEye 3 votes

Discrete version of pillbox function

This is an image processing question. In 2-D Euclidean space a pillbox function, $f(x)$ is given by: $$f(x,y) = 1\text{ if } x^2 + y^2 < R, 0 \text{ otherwise } $$ $R$ is come constant. If I …

asked by ncRubert 1 vote

Why does an ideal high pass filter on this image generate gray values

As seen from the image below, an ideal high pass filter was applied. Hence, stark changes in pixels from lighter to darker or vice versa show up on the filtered image. However, slower changes such …

asked by raaj 1 vote
answered by Aaron 1 vote

How is LMS/FXLMS noise cancelling different than simple polarity inversion?

Consider a noise-cancelling headphone: If I have a noise signal from the outside world, mic it, flip the polarity by multiplying by -1 (with an op-amp or digitally), delay by the appropriate amount, …

noise acoustics  
asked by Anthony Parks 1 vote
answered by Paul R 2 votes

PAPR in the SC-FDMA system

in wireless communication,compared to the OFDM system , why does the SC-FDMA (single carrier FDMA) system has a lower PAPR (peak to average power ratio)? regards, phani tej

asked by phani tej 1 vote
answered by zhimengfan 2 votes

Why does my overlap-add integrator in frequency domain result in distorted signals?

With help from the dsp guide and DSP-Related, I tried to implement a leaky integrator in octave/matlab. It seems to work in general, but there are a few problems. So that's what I do: Calculate the …

frequency-domain integration distortion  
asked by Markus 1 vote

Greatest hits from previous weeks:

What is meant by a system's "impulse response" and "frequency response?"

Can anyone state the difference between frequency response and impulse response in simple English?

frequency impulse-response linear-systems frequency-response  
asked by Ant's 30 votes
answered by Jason R 55 votes

Apply a Gabor filter to an input image

I tried to apply a Gabor filter with a specific scale (according to my values of lambda and sigma, so it is 7x7) and for 4 orientations (0, pi/4, pi/2 and 3pi/4) to a input gray scale image. In my …

image-processing matlab filters convolution object-recognition  
asked by Liszt 3 votes
answered by Ujjwal Aryan 0 votes

Can you answer these?

Image correlation confidence measure

I am trying to calculate the disparity between stereo image pairs. I'm using what appears to be the standard approach of correlating between a window of pixels from one image and a sliding window …

image-processing correlation stereo-vision  
asked by Simon B 1 vote

Recursive version of DFT as presented in Cooley-Tukey paper

The seminal paper of Cooley and Tukey provides an iterative method for computing the DFT for a sequence of length $N$. Specifically, they mention a method which utilizes the fact that $N$ can be …

fft dft  
asked by curryage 1 vote
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