Questions about computer vision -- please include example images to illustrate your problem.

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1answer
16 views

Selective Background Updating in Running Gaussian Average Method for Background Subtraction

I am studying the Running Gaussian Average Method for background subtraction. One alternative, as described in Wikipedia, also known as Selective Background Updating, is to only update the ...
3
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1answer
34 views

Multi object image segmentation methods

I want to survey the state-of-the-art in image segmentation. Is there a paper on how to segment multiple objects in an image? The segmentation papers I read, normally identify one of the many objects ...
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0answers
11 views

Intrinsic Matrices in Stereo Camera Calibration

Suppose I have two cameras, c1 and c2, observing the same scene. I can now Calibrate each camera independently (e.g., with MATLAB's Camera Calibration App) Calibrate both cameras simultaneously ...
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1answer
18 views

Is the Projection Matrix estimated using least-squares pose specific?

I am calibrating a camera and estimating the projection matrix using the least-squares technique described here. So far, I thought that the projection matrix that I got with this method was ...
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0answers
22 views

Any applications that need fast insert or delete for quadtrees?

I know that quadtree could be used in collision detection. But most articles I found are related with quadtree construction and retrieval. I wonder if there are some circumstances which involve both a ...
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0answers
36 views

Featurizing images of different dimensions

I'm building a non linear svm for images to solve a classification problem with domain {0, 1} and I'm currently doing featurization. What I want to do is create 3 features for each pixel representing ...
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1answer
20 views

Getting the essential from the fundamental matrix

Is it possible to get E from F? I suppose that can't work, because then I could calculate the the extrinsic (and maybe also intrinsic?) parameters of the cameras without a calibration object of known ...
2
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1answer
15 views

Fundamental and essential matrices, value of intrinsic parameters

I observe a scene with two cameras, c1 and c2, that produce two images i1 and i2, respectively. What I ultimately want to do is to use information of image i1 and image2 simultaneously, e.g., for ...
1
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1answer
34 views

Calibration and overlay of RGBD with a thermal camera

I have a thermal camera that I would like to overlay automatically to the output of a RGBD camera (e.g., Kinect). I can retrieve the intrinsic parameters of the thermal camera by using a special ...
0
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1answer
35 views

Bringing images into alignment

I observe a scene with two cameras, c1 and c2, that produce two images i1 and i2, respectively. What I now want is to bring i1 and i2 into alignment, that is I want to know where pixel (x,y) in i1 is ...
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1answer
23 views

What is the reason of using Gaussian model for Background Modeling?

I am a new learner to Background Subtraction (Background Modeling) and I am reading a few previous works on how it is performed. Starting with Wikipedia (by searching "Background Subtraction"), I ...
2
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2answers
48 views

find the actual size of an object from pixel coordinates

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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0answers
19 views

Feature detector that doesn't use corners

I'm trying to use computer vision to identify objects an image. I am currently using the SURF algorithm, but Harris and SURF both find virtually no points on our objects (a paper ball and a deodorant ...
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1answer
26 views

How to test image segmentation algorithms? [closed]

What would be an ideal environment/manner to judge the effectiveness of multiple segmentation algorithms? The goal is to determine which algorithms provide the best results for pre-clinical imaging. ...
4
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1answer
59 views

How to compare SURF points in two images

I know how to find SURF feature points and have code to find them, but I have no idea how to find the same point in 2 different images, I have laplacian, scale, orientation, descriptor, response and ...
0
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1answer
42 views

How do I detect and rotate a square?

I have recently written code for detecting path colors in a 2D grid and printing the corresponding path costs and it works fine for me. Here's my code; I am currently new to OpenCV and know only C++ ...
1
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1answer
25 views

What is the triangulation angle?

I start to work in the field of computer vision and read a paper in which the author states "When suitable correspondences between salient image structures have been established, the 3D uncerntainty ...
3
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1answer
64 views

What is the name of this problem in Computer Vision?

My google skills have failed me during research for a college project. Our task is write a program that describes an image in spacial terms, e.g. "Cat on the left of a chair", or for a simple image ...
1
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1answer
114 views

The Fundamental and Essential Matrix

Could someone, in plain english, explain the distinction between the fundamental matrix and the essential matrix in multi-view computer vision? How are they different, and how can each be used in ...
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0answers
41 views

Computer vision training procedures: SVM/AdaBoost vs Neural Networks

With SVM, adaboost or similar alogrithms, image training sets must be cropped with specific constraints (keep image cropping ratio the same, have object tightly cropped, same resolution) In general, ...
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0answers
23 views

Any good algorithms for 3d volume alignment by feature extraction, especially ones involve machine learning?

I am trying to align 3d mri brain images of different rat individuals. I have dozens of examples that have been aligned manually, which are good resources for machine learning. I am considering ...
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1answer
52 views

Can you determine rotation/camera calibration from series of images separated by pure rotation

I have a series of about 50 images, each separated by a small rotation and taken from the same camera. The images are feature-dense, and I can calculate a homography from image-to-image easily. My ...
2
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1answer
51 views

How to balance doing a literature review and just solving the problem yourself [closed]

I work for a company that has several projects involving computer vision. The literature rarely has papers on the exact problems we are solving. Furthermore, the state of the art in much of ...
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0answers
29 views

Histogram equalization - to increase “punch” and to limit local gain

The exercise 3.6 (Histogram Equalization) in Szeliski's Computer Vision - Algorithms and Applications asks: Convert the color image to luminance (Section 3.1.2). Compute the histogram, the ...
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26 views

Learning Hierachial representation of objects in a unsupervised manner

I am trying to understand how the how a hierarchal representation of an object can be learned in a unsupervised manner, using the method described in this paper. ...
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0answers
72 views

How to identify the z-ordering of objects in a computer vision or image processing scene?

Given that there is an image with objects in it, is there any method in computer vision to determine the z-ordering of objects. For an ideal image of three circles overlapping, I can determine that it ...
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1answer
112 views

Blob detection as Constraint satisfaction problem?

In image processing I have a black and white image which is represented by matrix {0,1}, I have to find blob (a region of connected pixels) in it. I'm confused, can this problem be reduced to ...
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0answers
60 views

Camera Matching Algorithm

I am trying to understand how camera matching (or match moving) works. I need to build a program that can move the camera in a way to match a 3D object to its projection on an image. For eg. if I had ...
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0answers
38 views

Patent-free algorithm for labeling a MRF/CRF

At the moment I'm implementing a video segmentation algorithm for moved foreground / background. In the literature often a graph-cut algorithm is used, which is patented by US6973212. Are there any ...
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1answer
70 views

What is the significance of the following equation in computer vision?

Say I have a set of sample measurements of a one dimensional curve in the image plane $f(x)$. What is the purpose of minimizing the following functional $$E(S) = \int \left[\lambda(S''(x))^2 + (f(x) - ...
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0answers
80 views

Technique behind the way google earth overlaps polygons on top of pictures

What´s the technique behind the way google earth overlaps polygons on top of pictures(like the ones users assign to streets and houses) ? It seems to be aware of perspective, and I don´t remember ...
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1answer
38 views

Recovering a 3D point from a perspective projection

Say I have a point $(P,Q,R)$ and that point lines in a plane with gradient $(A,B,C,)^T$. If I know the perspective projection of that point onto an image plane has the coordinates (x,y) and the focal ...
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0answers
41 views

Ways of object recognition in computer vision

In the field of computer vision, we talk a lot about this process of feature detection-description-matching as a way of recognizing objects. But on the other hand, there's also talks about object ...
0
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1answer
210 views

How to reconstruct the image from a neural network output?

I am trying to use the genetic algorithm to optimise a multi-layered neural network for image classification (i am using a subset of the MNIST handwritten digit data set as my initial dataset, but ...
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1answer
61 views

from when do we have the field of computer vision? [closed]

when was the field of computer vision created and what are the disciplines that gave birth to it? I would appreciate it if you could give some web references that have the answer.
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0answers
39 views

General object recognition versus specific object recognition

I have a question about the difference between general object detectors and specific object detectors. By specific object detectors, I'm referring to classifiers/object recognizers that are built to ...
3
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1answer
183 views

Training and testing image sizes for classification in computer vision

When training a classifier for object detection using features extracted from images (eg HoG features), how important is it that the images used for training fed into the classifier in their natural ...
4
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1answer
173 views

Advantages of adaboost over gentleboost in applications, or vice versa?

I've been researching on AdaBoost and GentleBoost classifiers, but can't seem to find a clear answer to the question: What is Adaboost better at classifying in computer vision? What is GentleBoost ...
2
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1answer
161 views

Similarity between two geometric shapes

I have two shapes in a 2D space, not necessarily convex, and I'd like to compare how similar they are. How can I define a robust distance metric to measure their similarity, and how can I compute it? ...
3
votes
1answer
394 views

Does there exist a data compression algorithm that uses a large dataset distributed with the encoder/decoder?

If my goal were to compress say 10,000 images and I could include a dictionary or some sort of common database that the compressed data for each image would reference, could I use a large dictionary ...
1
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1answer
61 views

How to compute Gabor feature vector?

I'm working on semi automatic texture segmentation using level set and gabor feature vector described by Manjunath und Ma [1]. I consider their feature representation is better than others since I ...
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4answers
124 views

Environment detection - How to detect “city” versus “landscape” background environment in computer vision?

I'm searching for computer vision or machine learning algorithms/methods that are used to classify or differentiate two outdoor environments. Given an image with vehicles, I need to be able to detect ...
3
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1answer
52 views

Environment requirement in training image dataset for classifier

I have a question about preparing the dataset of positive samples for a cascaded classifier that will be used for object detection. As positive samples, I have been given 3 sets of images: a set of ...
1
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1answer
72 views

Job sites for applied/interdisciplinary mathematics related to computer science? [closed]

I'm looking for job sites in applied/interdisciplinary mathematics, more specially, say postdocs or higher positions in mathematics and medical imaging, mathematics and computer vision. I'm aware of ...
2
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2answers
443 views

Object recognition - given an image, does it contain a particular 3D object of interest?

I have in mind a particular 3D object. Given an image taken by a camera, I want to check whether that image contains an instance of my object. For instance, let's say that the object is a bathroom ...
5
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1answer
699 views

Deriving the Sobel equations from derivatives

Many sites give the Sobel operators as the convolution mask for smoothing an image. However, I haven't found a single site that describes how you can derive the operators from partial first ...
5
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1answer
242 views

Automated lip-reading: inferring what someone is saying, based upon video of them speaking

Some humans can lip-read fairly well: by watching someone who is speaking, they can tell what the speaker is saying (even without hearing the speech). Has there been any work on building computer ...
1
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1answer
103 views

How does facial recognition work?

I'm interested in learning about how facial recognition works. I'm especially interested in the algorithms or approach that is used. What are the leading methods for facial recognition? Is there a ...
0
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1answer
127 views

Is developing an OCR considered a research project? [closed]

Is developing an optical character recognition system for an alphabet which has no previous ocr considered a reputable conference or journal worthy research project, given the fact that there are so ...
2
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1answer
251 views

Contrast Enhancement For An Image Using A Gaussian Function

I am working on a program that involves detecting faces in photos, i am reading a paper that someone has wrote and they said that they had more success detecting faces once he they applied some ...