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1500 questions
10
votes
4 answers
Books/resources for implementing various mathematical functions in fixed point arithmetic for DSP purposes
I'm looking for books or resources that cover the following in detail:
implementing mathematical functions (e.g., logarithm, exponential, sine, cosine, inverse) in fixed point arithmetic for DSP purposes.
techniques like using lookup tables, Taylor…
RuD
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10
votes
2 answers
Examples of linear/logistic regression applications
I was wondering about super simple applications of linear or logistic regression to signal processing (image processing specifically)?
I'm a math guy that's been asked to explain some mathematical methods to signal/image processing people, and I'd…
Cannoliopsida
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10
votes
3 answers
Filtering RANSAC Estimated Homographies
I am using RANSAC algorithm for homography estimation between pairs of images taken with cameras which do not have any translation between them (pure rotation and change of scale/zoom). It works well in half of the cases. The correct output looks…
Libor
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10
votes
2 answers
Filtering kinda "half-toned" image for OCR processing
I have a scanned PDF material to which I want to add hidden text layer, so I could index the document. I used ghostscript black and white tiff output device (tiffg4) to extract pages as tiff images, and here is example of what they look…
zetah
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10
votes
3 answers
Camera calibration/pin hole camera model and working out 3d position
I have a calibrated camera and have the intrinsic parameters. I also have the extrinsic parameters relative to a point (the world origin) on a planar surface in the real world. This point I have set as the origin in the real world coordinates…
Cheetah
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10
votes
1 answer
Solving a Convolution Problem of a 1D Signal
I'm finding in trouble trying to resolve this exercise. I have to calculate the convolution of this signal:
$$y(t)=e^{-kt}u(t)\frac{\sin\left(\dfrac{{\pi}t}{10}\right)}{({\pi}t)} $$
where $u(t)$ is Heavyside function
well I applied the formula that…
Mazzy
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10
votes
1 answer
What is the link between the homography computed over 2 images and the homography computed over the same images upside down?
With OpenCV, I compute the homography between, say, these two images:
and
Don't worry about the strange white form on the right side, it is due to the smartphone holder I use. The homography, given by findHomography() function (using points…
Stéphane Péchard
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10
votes
3 answers
Finding local peaks in-between samples
I have $n$ discrete samples of a seismic signal $y[n]$:
I want to find local maxima in the signal.
A naive test for if $y[n]$ is a maximum would be:
$$y[n]: maxima \textbf{ if } y[n] > y[n-1] \textbf{ and } y[n] > y[n+1]$$
However the maxima are…
Andy
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10
votes
1 answer
Understanding multirate filtering fundamentals
I am having trouble grasping some of the fundamental concepts of multirate filtering. I see from various sources that the basic building blocks of a multirate filter are the dyadic analysis and synthesis blocks.
Question 1:
The analysis block…
learnvst
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10
votes
2 answers
What is the normalization factor for the quincunx lattice wavelet transform, and how do you find it?
On pages 57-60 (preview was available last I checked, images here in case), there is a quincunx lattice transform described.
Lattice:
o • o • o • o •
• o • o • o • o
o • o • o • o •
• o • o • o • o
o • o • o • o •
• o • o • o • o
o • o • o • o •
• o…
bobobobo
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10
votes
2 answers
Finding the z-transform of $h[n] = a^n\cos(2\pi \frac{n}{F_s}f_0)$ for $n ≥ 0$ and zero for $n < 0$
So I'm trying to decide whether the cosine part is intended to be plugged in for $z$ or whether it is strictly part of $h[n]$. (the number a lies in the open unit disk)
I mean I was pretty sure it was all part of $h[n]$ but then upon performing the…
Zaubertrank
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10
votes
3 answers
Chroma-Subsampling: How to properly calculate the data-rate
I am having a hard time understanding how to calculate the data rate when leveraging chroma-subsampling in e.g. a Y'UV image:
I have the following examples for a calculation:
Image resolution: 352*288
Frequency: 25 fps
For (4:4:4) the example…
jottr
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10
votes
1 answer
How to remove stains from images?
I have this extremely distorted and stained image
Is it possible to remove this stain ? Could image inpainting help ?
Please help
EDIT : Another image
After applying anisotropic diffusion and representing image with imagesc(MATLAB)
I tried…
vini
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10
votes
1 answer
Could you describe the effects for varying different parameters of a canny edge detector?
Last couple of questions touched upon Canny edge detector
What are the limitations of a Canny edge detector? and
Best way of segmenting veins in leaves?
The basic outline of the algorithm is as follows:
a. Apply Gaussian Convolution. (Choice of…
Dipan Mehta
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10
votes
2 answers
How do I apply a function window to a signal?
How can I apply a window function like Hamming or Lanczos to a signal, using its coefficients?
I mean, which method can I use to do this? FFT? Convolution? Which method has the better performance?
walteram
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