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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Template matching for object recognition and pose estimation

I am currently reading a series of articles from Hinterstoisser about template-based real-time detection of texture-less objects and estimation of their pose. It is the series of articles that ...
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Translation invariance in max-pooling and cascading with convolutional layer

I am reading through this page about convolutional neural networks and I am confused about the part about max-pooling (downsampling a signal/image with the maximum value in a block). Apparently, one ...
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Convex optimization in signal processing

In signal processing, convex optimization plays a useful role in problems such as sparse signal recovery and filter design. What other places does convex optimization appear? For example, in ...
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Is the same to calculate the Moments of an image using only its vertex?

The below image is a convex filled polygon, to calculate its moments we can resort to the Hu Moments and if the image is very big, this could be an expensive process. But if we use only the vertex can ...
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15 views

Image Filter Class Hierarchy [closed]

I need to create a hierarchy of Image Filter classes in C++. Do you have any ideas how to make the hierarchy and where to find source code?
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3answers
67 views

why the ultasound image is noisy by speckle noise?

My first question : I want to know why an image is noisy ?. why the ultrasound, SAR and Laser... images are noisy by a multiplicative noise not an additive noise? Another question : The dominant ...
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camera calibration: why chessboards?

Chessboards are very frequently used for camera calibration, this website also talks a bit about why: wiki. One of the reasons is, that chessboards define many natural interest points. Now my (very ...
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1answer
35 views

How to estimate radial distortion from lens characteristics?

Is there a way to estimate the radial distortion coefficients without calibration, given the lens characteristics, such as its diameter and its focal length? Typically for camera calibration a ...
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2answers
33 views

How to find the actual size of an existing object from the pixels of an image?

I am quite new to vision and OpenCV, so forgive me if this is a stupid question but I have got really confused. My aim is to detect an object in an image and estimate its actual size. Assume for now ...
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26 views

Difference between video mosaicing and video stitching

What is the difference between video mosaicing and video stitching ,is this both are similar or is there any methodology difference?
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13 views

Use the line function commend matlab of PDE toolbox in image processing

I want to use the line new command of PDE toolbox as Matlab R2015a to restore a noisy image with gaussian noise. The PDE is : \begin{eqnarray} \nabla.(\frac{ \nabla u}{\sqrt{1+|\nabla u|^2}}) ...
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11 views

Understand about registration between spatial prior and original image

I am working in level set/active contour method using spatial prior information . The main papers that I am focusing:"Automatic segmentation of neonatal images using convex optimization and coupled ...
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39 views

Using SURF algorithm to match objects on MATLAB

I am trying to find the difference between two images, using Matlab. The classic built in function that Matlab provides for this is because the two images don't have the same dimensions (The objects ...
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42 views

Question about Difference of Gaussian (DoG) algorithm

I am recently learning about Computer Vision and I am having a trouble understanding Difference of Gaussian (DoG) algorithm. I get how the algorithm works in high level idea, but I am trying to ...
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6 views

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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1answer
34 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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11 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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1answer
35 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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12 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
157 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
38 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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59 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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1answer
51 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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31 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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1answer
67 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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128 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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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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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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20 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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16 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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95 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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78 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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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
41 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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1answer
50 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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2answers
139 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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2answers
217 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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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
50 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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10 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
66 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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33 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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23 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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28 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 ...