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1500 questions
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Get histogram of edge lengths/orientations in an image using OpenCV

In the process of trying to estimate whether a ROI contains [Japanese] text, I need to get a rough count of edges, hopefully binned by length and/or orientation... I think this would give me strong-enough features to judge if the ROI is likely to…
Dave
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Combining two images

I am working with speckle noise reduction in ultrasound images. I have used wavelet transform for removing the noise by eliminating certain frequencies in order to eliminate any existing noise. Since in an image HH,LH,HL components contains most of…
preethi
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Sampling Theorem and Dirac Comb

I am reading "The Scientist and Engineer's Guide to Digital Signal Processing" and trying to understand Figure 3.5 below which is about the sampling theorem and aliasing. I do not understand the picture of the frequency domain. The signal can be…
user782220
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Angle Averaging

I am working on an 802.11a demod that works, for the most part, but has a bug that causes intermittent errors. I haven't finished characterizing it, but it appears that the problem is in my equalizer block. 802.11a is an OFDM signal, and each OFDM…
Jim Clay
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Which domain used for denoising additive and multiplicative noises

I want to know what is the difference between additive noise, multiplicative noise.. In what domain these noises are handled to remove? I am interested particularly in image dataset Does different domains are used in case of satellite imaging where…
loljesus
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3 answers

Zero-pad before or after windowing for FFT

What's the correct way. Should I zero-pad a signal before or after applying a windowing function?
mhawker
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How do you choose the optimal number of taps in a windowed image scaling filter?

I'm attempting to use a filter to scale an image and for the most part, I have something that appears to work. But now I want to be able to generate a filter with an optimal number of taps. I know in general that the more taps, the better. But…
Dennis Munsie
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Removing a sinusoidal artifact from a set of movie frames

I am doing some post-hoc analysis of a dataset consisting of a series of movie frames that are contaminated by a strongly periodic artifact. I would like to remove this artifact from my frames. For ease of plotting I've just reshaped my array M of…
ali_m
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Convolution Kernels for Image Filtering

As I understand it, in image processing, when it is desired to apply a filter of some sort to an 2D image, a kernel is applied to all the pixels of the 2D image in a process called convolution. Median, Gaussian, Bilateral, all are examples of…
ConfusedStack
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Image Processing - What Is a Gradient Domain?

What is the gradient domain? Does it relate to the Laplace Pyramids? I found only articles assuming you know what it is and not define it, can someone please define what is it and what it is used for? The reference used is Seamless Image Stitching…
0x90
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JPEG steganography

Aside from Jsteg of Derek Upham, Outguess of Neils Provos, and F5 (improvement of F3 and F4) of Pfitzmann and Westfeld, What other methods can you use in information hiding in JPEG images? The methods I mentioned above hide the message in the DCT…
Frank Smith
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Black box signal prediction

I have a stateful black box with four real-valued inputs and one real-valued output. My problem is to predict the output at each moment in time, given the sequence of inputs seen up to that point. During a learning phase, I can vary the inputs…
Adam Crume
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Detect and isolate veins in the palm?

I am trying to figure out a way to find out the vein pattern in the hand.. Please could someone suggest ways to do the same.? I know first i would need to find the ROI in the image and perform further processing .. Can gabor filter be used as one…
vini
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Using DTW on the MFCC's to match a spoken word to a template

I am trying to code a simple algorithm in MATLAB that would be used to detect a single word. The goal would be to have a user record the word one time to act as a template, then make the user repeat the same word to try and detect it. Searching on…
user5907
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What Are Less Computationally Demanding Alternatives to the Viterbi Decoder?

What are less computationally demanding alternatives to the Viterbi Decoder? Ideally what I would like is a list of the most commonly used approximate methods, along with brief pros and cons.
gyroidben
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