Computer vision includes methods of processing, analyzing, images and high-dimensional data to form high level understanding and recognition of the scene or images.

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Classifying images with standing\sitting people

I have images that contain two people. They can be divided into the next categories: Both people are standing. One person is standing, and one is sitting. Both are sitting. I want to classify each ...
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Histogram as a feature in Make3d

I am reading the one of the publications of the Make3d project. the NIPS one. which uses a machine learning approach and MRF to estimate the depth from a single image. In this paper in part 3.2 the ...
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17 views

Is opencv work fast with android like in desktop?

I am working on android applications and I am now using openCv for it , but when I apply the build in filter algorithms for my app it works slow and show result ...
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2answers
53 views

Eigen value and Eigen Vectors in Image Processing

I have been reading about eigen values and eigen vectors but i haven't be able to find any decent explanation relating their application in image processing/computer Vision for example say face ...
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9 views

base curve detection and skew estimation in Binary Document analysis

In document image analysis i came across two differnet sets of literatures. One is skew estimation of text lines and other is base curve detection of text lines. My questions are:- How the two ...
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13 views

How to use cross-ratio in position estimation?

I'm trying to track the horizontal motion of a pen's tip using a single camera. My current approach is to use the Cross-Ratio between 4 colinear points. My idea is to place 3 LEDs along the pen's ...
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22 views

What does normalizing gradient means?

Since my algorithm needs to detect long, coherent edges, the estimated local magnitude P for each pixel is normalized with respect to the magnitudes in it’s local neighborhood W (i.e., a 5x5 window). ...
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1answer
39 views

Best Guess Rectangle

I am using openCV to find a particular object, and am trying to find a way to make it locate the object consistently. The object's location will be determined by taking 30 frames and trying to find ...
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1answer
24 views

(Rough) camera calibration of manipulated images

Coming from a photogrammetry background, I am quite familiar with camera calibration, and the common assumptions that are used for crowd-sourced images (i.e. center point in the middle of the image, ...
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2answers
35 views

Computer Vision - Gaussian Pyramid, Scale Space and Pattern Matching

I am planning to implement a pattern matching algorithm using something like correlation as a matching metric. I know that the template I am going to use will, if present, have different sizes in the ...
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1answer
71 views

How to make filters?

I am trying to make filters like sepia filter in my app like other photo editing applications , till now I don't have any idea about it , Can any one help me out ...
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1answer
38 views

Incoherence: Compressed Sensing (CS) vs Matrix Completion (MC)

I am seeking a clarification of the concept of Incoherence within the MC framework. Specifically, 1) the literature mentions the application of a "strong incoherence" given a set of assumptions. ...
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1answer
44 views

Why are 2nd order edge detectors such as Laplacian more susceptible to noise?

I've been told that they are influenced by noise considerably more than that of a first order edge detector such as a Gaussian. But why?
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1answer
48 views

Calculate the entropy of Turkish alphabet and compare with the entropy of English alphabet with using Matlab?

Calculate the entropy of Turkish alphabet and compare with the entropy of English alphabet with using Matlab? How can ı do this question anybody help please?..
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1answer
91 views

What is intensity centroid?

So, I am reading a paper about ORB and it happens to calculate the direction of corner from it center . According to Rosin the author of the paper;moments of a patch is given by and the centroid ...
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2answers
65 views

What does natural scene image data-set mean?

I came across a paper that is trying to classify and detect object(s) present in what they call a natural scene data-set. They have images containing objects like cars, bikes and people. Can anyone ...
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37 views

Object detection approach

I am trying to detect the vehicles for that i used the SURF/SIFT and BOW with SVM approach but vehicles are of different type and i just studies that SURF/SIFT is for one specific object detection ...
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1answer
44 views

Queries on Kalman Filter

I am trying to apply kalman filter for video processing , i am studying about it from different sources but it take me towards question that if i don't know that where my object come in frame mean i ...
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1answer
70 views

What does an image of Fourier Transformation of an image tell us?

First time studying image processing... I just don't understand what does fourier transformed image of an image describe? For example consider given following pictures, The first one is the image, and ...
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1answer
50 views

Is there any good book regarding Image Processing Algorithms for Feature Extraction and Matching which gives examples in MATLAB?

I have been looking to implement feature extraction and matching in MATLAB. For this, I've read many algorithms, but i'm not able to understand how to implement these in MATLAB. Is there any Book ...
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1answer
58 views

Particle filter, resampling step implementation

I am not very good in statistic neither in probability theory, and I do not completely understand the mathematical background of Monte Carlo simulation or SIR sampling, but I'd like computer vision ...
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1answer
57 views

What steps come after finding the gradients of the SIFT key points?

I am using a SIFT algorithm to extract features from an image. I understand that the SIFT descriptor first finds the extrema and then finds the gradient and direction of each of these interest ...
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1answer
78 views

Is there any good book regarding 3D reconstruction from 2D images? I prefer to work in MATLAB

I am working on a project regarding 3D reconstruction of 2D images. I have understanding of finding and Mathcing the keypoints and its algorithms; but i am not able to replicate the theory in MATLAB ...
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1answer
40 views

Database into training and testing images

I am trying to compute the accuracy of the HMAX model. I am using the Face category (containing 435 images) from the Caltech101 database. I split it into x training and y testing. At each time, when x ...
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42 views

Sparsity limits of compressed sensing - is this right?

Compressed sensing (CS) guarantees exact object recovery (or with high probability) given a) sufficient measurements are taken in a sparse basis which is b) incoherent vis-a-vis a given object ...
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1answer
41 views

What is localizability in Computer Vision?

Please consider the following excerpt (from Rodrigo R, Zouqi M, Chen Z, Samarabandu J.: Robust and efficient feature tracking for indoor navigation): Robust feature tracking is a requirement for ...
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1answer
34 views

what are best features [closed]

I am doing OCR for Kannada and English. What are the best features in image? Please also tell me some tools to perform OCR before implementing it as code (like Rapiedminer for machine learning).
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1answer
106 views

Corner detection using Chris Harris & Mike Stephens [duplicate]

I am not able to understand the formula, What is $W$ (window) and intensity in the formula mean, I found this formula in opencv doc ...
4
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1answer
41 views

Base line detection of text lines

I came across various works in the literature of document analysis addressing the problem of detecting base lines of multioriented texts. But no amount of search could give me satisfactory answer to ...
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2answers
120 views

Refining lines in an image with openCV

So in my project I am extracting the lines of an image with openCV2 by firstly creating a skeleton: I convert it tp a binary image, invert it (to make it work with morphological operations) and then ...
2
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2answers
68 views

Constant used to determine the minimum samples in Compressed Sensing

A key result in compressive sensing states that, with high probability on the random draw of an $\ m × N$ Gaussian or Bernoulli matrix $\ A$, all $\ s$-sparse vectors $\ x$ can be reconstructed from ...
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1answer
66 views

Machine Learning in FAST corner detector

This paper by Edward Rosten and Tom Drummond 2008 describes choosing interest point via machine learning approach using ID3 algorithm. I understand the concept of the ID3 they are using. But my ...
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1answer
39 views

recovery of sparse vectors

When looking for a sparse solution to $\ Az = y $, under what condition(s) does the nullspace $\ N(A)$ of a matrix $\ A$ not contain any $\ 2s$-sparse vector other than the zero vector, i.e $\ N(A) ...
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2answers
80 views

Minimum size for positive samples for HOG (Histogram of Gradient) detector training

I'm going to train a HOG detector for detect objects (pedestrian head) with SVMLight library. But my question is not about implementation. I'm wondering how to collect samples. I have to use some ...
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3answers
105 views

Is it an excessive pre-processing step in image processing?

I wanted to consult with some experts whether or not this pre-processing step is excessive for what I'm trying to achieve. I am in a similar scenario as the author of the article, where I have many ...
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3answers
141 views

Different representations of images and their purpose

I'm doing a small overview of different image representations used in image processing and computer vision. For every representation, I would like to have (at least) the following information: the ...
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1answer
189 views

Ambiguous results of phase correlation in pattern recognition

We are using phase correlation to find pattern on image and what we get is 15% of results is spurious. Ours pattern has 32x32 pixels and image for research has 32x512 pixels. So we put Pattern to ...
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1answer
32 views

What is Earth Movers Distance and how is it used in pattern recognition?

I have obtained this from Wikipedia about the application of Earth Movers Distance to pattern recognition. Can anybody explain the concept of signature used in this ...
4
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2answers
208 views

Understanding SURF features calculation process

So, I was reading the paper on SURF (Bay, Ess, Tuytelaars, Van Gool: Speeded-Up Robust Features (SURF)) and I can not comprehend this paragraph below: Due to the use of box filters and integral ...
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3answers
79 views

Detect keypoints in images without corners

I am trying to achieve a pattern matching between an image and a scene in which the image is. I am having problems with some images that does not contain corners, since SURF is not able to find ...
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0answers
153 views

BRIEF descriptor and matlab code [closed]

i want to know more about brief descriptor algorithm and matlab code for this. the points copmare with another what choice them. e.g. 128 point at patch how are choose.? thanks
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1answer
70 views

How the select the representative frame when detecting vehicles

I am detecting vehicles from the video (taken with a camera), and the vehicle detection part works fine. My problem is that I should always extract only one representative frame per vehicle, and not ...
2
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1answer
133 views

Barcode localization in difficult environments

I'm creating a program for localizing types of barcodes. (I know plenty exist, that's not the question :) ) I'm focusing for the time being on 1D barcodes. The difficulty I have is that the barcodes ...
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1answer
17 views

Is “early vision” chronological or process

This might sound silly, but I have a language barrier type of question, and I was hoping someone could clear up this misunderstanding: I've seen the term "early vision" several times in papers I've ...
2
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1answer
119 views

Iterative Lucas-Kanade algorithm

How is iterative refinement is applied to the estimate obtained by Lucas-Kanade algorithm? I am familiar with the following steps: Estimate velocity at each pixel using one iteration of Lucas and ...
2
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1answer
77 views

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. ...
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4answers
85 views

What is a labeler?

My computer vision / image processing professor uses the term "Label", to represent part of an image, but cannot explain in a way that makes any sense to me what it is. She says this is a somewhat ...
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29 views

What is contextual Knowledge?

Contextual knowledge (CK) is used in some AI application, Can someone give me a concrete definition of this term. I am working on ontologies( a set of concepts and relationships among them) and ...
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0answers
49 views

Landmark Extraction via Kinect

I am working on a SLAM algorithm as part of my research and I am having issues reliably extracting landmarks from sensor (Kinect) data. (I've never dealt with machine vision before.) I am looking ...
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1answer
156 views

Object detection versus object recognition

I have a slight confusion differentiating between object recognition and object detection. Some people say object detection is a sub-topic of object recognition? Can someone clarify the the difference ...