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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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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36 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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53 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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32 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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4 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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6 views

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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16 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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1answer
49 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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31 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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1answer
67 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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1answer
28 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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33 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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18 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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2answers
183 views

Whether phase congruency and phase coherence terms are same or different?

I am beginner in Image processing.I am studying the importance of phase in signal.Can anybody explain what is phase congruency ? Also,I am confused between terms i.e. phase congruency and phase ...
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1answer
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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1answer
30 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
56 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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22 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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21 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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20 views

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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20 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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1answer
66 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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16 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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1answer
54 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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40 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
156 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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86 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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37 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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2answers
93 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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1answer
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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1answer
353 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
73 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 ...
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43 views

Non-maxima suppression of gradient image

I'm new to image processing, However I was trying to learn how to detect edges using Sobel filter I had obtained the image gradient in both X and Y directions successfully using Emgu built in ...
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1answer
33 views

How to apply the provided wave transforms on an image

I want to implement one of the following mappings in MATLAB and verify its performance on an image, but I couldn't. Please help me with the implementation
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2answers
249 views

Segmentation of overlapping noisy parallelograms in a binary image

Edited. Previously this question was named "Segmentation of overlapping pulses in a binary spectrogram" and it was stated in slightly different way. I'm apologise to those users, who were affected by ...
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2answers
44 views

Pinhole calibration

This is a conceptual question I am having difficulty to understand due to my limited knowledge of computer vision: If a pinhole calibration or any calibration is a mapping from world coordinates to ...
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100 views

How can I make the background color white for this Grab-cut algorithm written in Python?

I am new to Image Processing and am using Grab cut algorithm to extract the foreground objects from images as a part of my project. Below is the code written in python to do the same. The problem is ...
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54 views

Distinguish between 2D and 3D objects according to depth

I'm trying to distinguish by code between a real 3D object and its picture - a 2D object, based on depth information. However the picture (= the 2D image) might be captured from noisy background, so I ...
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1answer
36 views

Video: Detecting a digital timer and when it ticks

Input: A video with a digital timer, possibly several hours long, such as this video. The timer might use any font or color, and might be located anywhere on the video, but it probably won't fill the ...
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2answers
301 views

What is the rate of expansion of an image as it aproaches the human eye?

My intuition about the scaling (x,y) of the 2d representation of the 3d object generated by our native visual processing system tells me it accelerates as it ...
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68 views

How to implement HOG with trilinear interpolation by Matlab?

I am studying HOG. I have find the code code1 and code2 about HOG. However, both of them don't implement trilinear interpolation. I have also read some websites, including web1 and web2. I still don't ...
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3answers
95 views

Training own classifiers using trainCascadeObjectDetector for face detection

I want to train a cascade classifier to face detect. I read this page. But I wont use trainingImageLabeler app, because I already have face and nonface database sized 24x24. How I use ...
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1answer
85 views

How to remove text region in a document image? or extract image from a document image

Given a document image (i.e. newspaper), how to extract photos in it or remove text region? I think traditional OCR methods may not be suitable here, as I don't need to recognize the text, and OCR is ...
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35 views

How do I deal with occlusion, warping, or perspective distortion for object detection

I am using SIFT features for detecting logos in clothes. SIFT is quite powerful, as it is scale invariant, but how do I deal with the problem of occlusion and warping? More specifically, the logos in ...
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What are the main roles of leverage scores and low rank approximation in computer vision applications?

I'm just starting to learn about the field of computer vision. I would like to hear from experienced SE users regarding the following questions 1) I know that computer vision is driven by numerical ...