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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How much does sub-pixel sampling affect depth resolution in stereo vision?

If I have 2 sets of camera-pairs, to setup 2 stereo vision systems. Setup 1: cameras have 2940x2940 pixel density Setup 2: cameras have 98x98 pixel density with 30x sub-pixel sampling to get same ...
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23 views

Camera calibration using multiple images

I am trying to get the hang of camera calibration. For this purpose, I have mainly watched this lecture on youtube: Lecture 12: Camera Model by UCF CRCV. I believe that I understood the main ideas: ...
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9 views

How does a system like Kinect determine the (x,y) location of point projections?

I'm designing a system that will project structured light onto an object in order to measure the distance between the object and a sensor -- much like xbox kinect! However, the most effective method ...
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18 views

difference between feature detector and descriptor?

I am new to feature detection and tracking. can anybody please explain in detail the difference between detector and descriptors. which among these are detectors and which are descriptors : Harris, ...
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Camera Calibration: Homography method giving wrong coordinates [closed]

I am using OpenCV with C++. I have the pose matrix and 3D coordinate estimation method mentioned in this post. My homography matrix looks like this: [0.06203848937168999, -0.9979381329101257, ...
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9 views

Error correction in a video feed

How does one write software to minimize errors? As in, say I'm trying to look for contours in a region of interest. After writing down the program for contour detection, when I test it the contours ...
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2answers
144 views

relation between luminance and eigen values of an image

There are some research papers in the literature which apply Singular Value Decomposition (SVD) on an image to decompose the image matrix into U, ...
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1answer
26 views

Machine Vision - Infinity Focus effect

I am working on a research project that involves machine vision. The camera we are using implements infinite focus - I have been informed that this can affect the accuracy of computer vision ...
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3answers
23 views

Segmenting and labeling chessboards through computer vision

With almost no experience/knowledge in computer vision, I am currently trying to segment and label the separate squares on a chessboard (i.e. a1 ... h8). My goal is to use the information to ...
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43 views

Bounding box around text given a single point inside text using opencv

I am trying to figure out a way to detect a "best-fit" bounding box around a text, given a single pixel(or a small set of pixels) inside this text area. Consider the following image: Given the ...
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45 views

Metal Defect Detection

I am developing a machine vision project to find defects on metal surfaces. I want to learn and implement algorithms which commercial systems are use for metal surface defect. My sample object as ...
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27 views

what is the difference between HSV and CIE-Lab color space? [closed]

when do we use HSV color space and when do we use CIE-Lab color space?
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What is the relationship between the Harris corner detector and shape operator?

From my understanding, the Harris corner detector looks at the gradients in the principal directions of a small region. Why are the eigenvectors of the matrix the principal directions? More ...
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63 views

Finding aberrations and/or unknown features in an image

Is it possible to find unknown featues in an image or in other words aberrations from a normal image of some type? For example: Imagine you have lots of pictures of different faces, so all are ...
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113 views

How to learn image processing / computer vision in a practical way?

I am new to the field of image processing / computer vision and I find it very hard to get my hands on the subject. I read a lot about the basics/theory but I feel in no way able to use this knowledge ...
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46 views

pre-processing to improve feature detector before tracking

I am trying to make tracking for soccer player, I need to detect features from this player and then estimate the distance difference of these pixels over number of frames. first I have to detect the ...
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6 views

what is in intuitive explanation of local derivative pattern (LDP)?

Zhang et al. proposed the LDPs for face recognition . They considered the LBP as the nondirectional first-order local pattern operator and extended it to higher orders ( th-order) called the LDP. is ...
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what is the drawback of DLBP(Dominant local binary pattern)?

Although the DLBP features encapsulate more textural information than the conventional LBP features, they lack the consideration of distant pixel interactions. The reason is that the binary patterns ...
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18 views

How to implement extended structure tensor

I am implementing an extended structure tensor that defined as where (*) is convolution operator; K_sigma is a Gaussian kernel with standard deviation sigma. The subscripts x and y denote the ...
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15 views

SIFT - Lots of Hessians are not-invertible

I'm trying to code the SIFT algorithm. In the step of using Taylor series to find accurate locations of key-points, the number of key-points plummets from hundreds of thousands to fewer than 1000. ...
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80 views

Lane detection and tracking using B-snake?

I am truly sorry if my question sounds little bit stupid, but I am getting stuck at this part for a long time. I am currently working for my final year project of lane detection for curved road using ...
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32 views

Why is MRI more expensive than CT?

I am not asking how MRI scans are different from CT scans, but rather why they are more expensive. I know that CT scans take longer for starters, and am wondering whether this is essentially the only ...
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77 views

Why different smartphones with same Megapixel camera have different quality of image?

I am image processing student. Nowdays there are different brands of smartphones available. But the common thing is two different big brand smartphones with same Megapixel camera have different ...
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14 views

Nash equilibrium for big data [closed]

How effective is Nash-equilibrium for big data cases in scenarios like crowd and traffic monitoring? Crowd and traffic scenarios are competitive environments which suit well to Nash-Equilibrium. Are ...
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37 views

How to plot ROC curve for weka multilayerperceptron?

I am working on an image classification project I use multilayerperceptron,how do I plot ROC curve.I use weka's perceptron.
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41 views

How to Linearise an Input Image before applying Color Correction?

I'm doing color correction on Raw images taken from Camera directly. I want to make my Camera reproduce same colors as my Target camera. Here are the steps I'm following: Take Target Color values ...
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19 views

Algorithm to find similarities on a huge database querying one image [duplicate]

After days trying to look to some algorithms, I haven't found any good for my approach. My problem is the following one: I have a large dataset, for example of 2.000 images and I'm trying to query ...
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3answers
128 views

Matching two very similar images

I have two images for the same object from the almost same perspective (no more than 1-2 degrees or 1-2 mm is acceptable). I want to change the perspective of one of them to match exactly the other so ...
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208 views

What is phase congruency?

I am beginner in Image processing.I am studying the importance of phase in signal.Can anybody explain what is phase congruency ?
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19 views

Why is the backprojection of the Middlesbury depth map “cone shaped”?

I wrote some come to backproject depth maps. Testing it with the Middlebury cone set, I get: First of all it has noise, which I shouldn't get from the ground truth, but more importantly it seems ...
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38 views

System Requirements in Computer Vision

I am interested in developing a research on object recognition using artificial neural networks. The problem is that I don't know what the system requirements of a computer vision project. A raspberry ...
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9 views

Face detection options

I'm interested in using some precanned face detection algorithms. What are the current state-of-the-art options that would detect faces without doing any training? OpenCV? ccv lib? Others? As far as ...
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1answer
63 views

Machine Vision Techniques for Sign Language Recognition and Interpretation(using Matlab)

I'm currently working on applying Machine Vision methods to sign language interpretation and I'm really overwhelmed with the body of knowledge out there. I've been reading up on object recognition ...
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29 views

How to use weka for multiclass classification with intersection kernel?

Can anyone please explain to me how to use weka for multiclass classification with histogram intersection kernel.I need to classify bike,car and flower images.
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25 views

Difference Between Least Square Error Recognition, Logistic Regression, and a Certain Nearest Neighbor Neural Network

Least Square Error Recognition from JavaOCR finds the least mean square error from a training image pixel by pixel. Logistic regression from this site, on the other hand, seeks to minimize the error ...
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What exactly affine covariant features are?

I was reading about different blob detection algorithms. And I found an statement that determinant of Hessian is a affine covariant. What does it mean?
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24 views

AR-like marker detection

Let's say I have a grayscale image in which I wish to detect (and later identify) a marker. It is also my task to construct an appropriate marker. As image is grayscale that means the marker should ...
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90 views

How do I implement LIBSVM for multiclass classification using java?

I am currently working on an image classification project ,where i need to use bag of features model with libsvm(HIK kernel) for classification.I have extracted sift feature and created a visual ...
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20 views

Plotting Basis of 3D Steerable Filter

I am plotting isosurface plots of Basis of 3D Steerable filters which should look like Spherical Harmonics of first Zero, first and second order plots. Correct me ...
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61 views

I have some questions about background subtraction with Gaussian Mixture Model (GMM)

I'm learning about Gaussian Mixture Model (GMM) for background subtraction.. And have some questions about it.. In Chris Stauffer paper "Adaptive background mixture models for real-time tracking" ...
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42 views

How to straighten the edges?

Are there standard efficient ways/algorithms to make edges in an image more straight or axis-parallel (horizontal or vertical) ? I have images that look like this: This is part of a segmentation ...
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2answers
219 views

Vehicle detection in matlab [closed]

I am new to matlab and computer vision. I used the code given in the link to detect cars. But the problem is the shadow is also being detected and tracked. Can anyone tell me how to modify the code so ...
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91 views

Efficient Hessian-Laplace blob detector implementation

As it is mentioned in a paper for SURF, it is possible to approximate hessian determinant using integral images. If I want to implement Hessian-Laplace detector, is it feasible to also approximate ...
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52 views

contour matching

Im am trying to extract contours from an image and match them with a list of contours I already have. The contours in the image are surrounded by a large black/dark rectangle. Here are the steps I ...
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110 views

Contrast stretching Equation problem

How to determine $a$ and $b$ in this equation. I know how to determine $c$ and $d$ by looking at the intensity histogram. But what about $a$ and $b$? $$P_{out}=(P_m -c)\left( \dfrac{b-a}{d-c} ...
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29 views

What does one call this method of grid fitting?

The input space has artefacts that are already in a grid-like layout: I'd like to be able to fit/draw a grid over the artefacts so as to separate them, preferably with lines on average mid-way ...
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434 views

Circle detection opencv

I Would like an explanation of the parameters for opencv's HoughCircles function. I'm new to image processing in general and I have recently started using opencv. ...
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26 views

How to programatically perform image segmentation in real-time

I am currently trying to segment ultrasound images of blood vessels (video frames), such as the one directly below. Using a simple binary filter on the saturation channel (code below), I can get a ...
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2answers
76 views

Best Car Recognition Algorithm

Could anyone suggest the best algorithm for a real-time Car recognition (say in a parking space)? I am planning to implement the same on FPGA as well. Kindly suggest. Thank you.
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Need to order a set of colors to build a feature vector

I am working on Computer Vision task of object classification with python and OpenCV. Currently I am extracting some characteristic colors of an image using K-means clustering on all the pixel to ...