Questions tagged [computer-vision]

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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3d CT segmentation

It's my first attempt at 3D analysis. I am trying to segment a 3D CT data. My case study is very simple: trying to segment circular objects in my data. Do you have any suggestions on how to achieve ...
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How much is the chance for a pure mathematician (geometer) to get a postdoc in imaging if he switches fields after Ph.D. and apply for one? [closed]

Before I start my question, I should probably mention that this question might not be the right question to ask here, but I tried academiabeta, and stackoverflow, but without getting any to-the-point ...
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resources for learning more about pedestrian tracking

I would like to build a computer vision application capable of doing robust pedestrian tracking in potentially crowded environments from a single video source. To this end I would like to find ...
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1answer
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Questions about log polar transform

I read various papers about the log polar transform and its application on template matching with images and have some questions: In "Image Registration Using Log Polar Transform and Phase ...
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1answer
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Jacobian of affine warp in Lucas-Kanade image alignment

I hate this kind of questions, but I'm really stuck. I'm trying to implement Lucas-Kanade algorithm as described in this paper (see pages 4 and 5). Unlike most explanations I've seen they don't assume ...
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1answer
885 views

Are SURF descriptors normalized with respect to orientation?

I know that both SIFT and SURF descriptor vectors are normalized with (unit vectors) to deal with illumination changes, but as far as I can see, the SIFT descriptors are also normalized with the major ...
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3answers
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segmenting region of interest (ROI) from background

I am dealing with images from biological slides and want to segment out the ROI (cells) from the background. I have tried k-means clustering, otsu thresholding, adaptive thresholding, edge detection ...
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Comparison of size of an entity in different images with different resolutions? [closed]

Can we compare the size of two objects appearing in different images with different resolutions?
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2answers
446 views

Detection periodic elements in image

I am working on a university project in which I need to find a periodic net element in an image. The net is a set of diagonal lines in a specific angle ( which I don't know in advance ) on a noisy ...
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1answer
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Hand detection in matlab

I am beginner and I want a help to know how to detect hand in Matlab. First, I need code which detects skin and then draw a rectangle around a region so it show to me face and hand. When I try to ...
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How can I create polygon estimates of each body part/limb that is present in an image which always contains one person?

Background I am working to identify and isolate each human limb of a known person, in pose, in an image which is relatively noisy. It should also be noted that the image is a snapshot extracted from ...
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trainCascadeObjectDetector seems to be missing from MATLAB R2012b

I wish to use trainCascadeObjectDetector to train on new objects (other than faces); I have the Computer Vision Toolkit installed; but this function trainCascadeObjectDetector seems to be missing from ...
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Errata Corridge in Gabor Filter Documentation and Frequency Response

I have a really simple question regarding this tutorial I found on Gabor filters. Check the very beginning section, equations (1), (2), (3) and (4). Is there any chance that equation (4) is missing ...
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177 views

Affine detector + SIFT descriptor

I am approaching to the Oxford Buildings dataset which contains already computed SIFT descriptors from affine detected keypoint locations. Usually SIFT detector provides to its detected keypoints ...
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2answers
921 views

Estimating Plane Pose Without Knowledge of Intrinsic Camera Parameters

Assume a camera has no skew, and has square pixels, that is, its camera-calibration matrix, $K$, looks like: $$ K = \left[\begin{matrix} \alpha&0&u_x\\0&\alpha&u_y\\0&0&1 \end{...
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1answer
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Image processing: using PCA for 3d object recognition

I read this lecture on using PCA/eigenfaces: http://www.cse.psu.edu/~rcollins/CSE486/lecture32.pdf And I want to use this general procedure to recognize a 3D clay model that I took pictures of from ...
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1answer
139 views

Fourier Transform Computer Vision Textbook

I am required extremely fast to fill the gap and learn Fourier Transform with application in Computer Vision. It was easy to find mathematical aspects of Fourier Transform, but I am more interested ...
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Help in Retraining a HOG Descriptor using SVMLight

I am currently trying to count cars using OpenCV 2.4.4 with a HOG descriptor. Because a model for car detection is not available in OpenCV, I am creating my own model using SVMLight and a dataset of ...
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Geometric models to discard image features

I am working on the implementation of a location recognition pipeline as detailed in the section 5.4 of the paper Leveraging 3D City Models for Rotation Invariant Place-of-Interest Recognition: ...
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1answer
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Counting vechicles in an image

I have been trying to implement an algorithm for successfully counting cars in an image. I have tried implementing A Method for Vehicle Count in the Presence of Multiple-Vehicle Occlusions in Traffic ...
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1answer
46 views

Intensity change after filtering this image?

I need to filter the image raster below with the following mask: 0 1 -1 0 and the Image Raster: ...
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Points of interest in a spectrogram

We have several audio tracks, all of which are different versions of the same track under one type of distortion: the speed of the track is increased by a constant factor K (hence frequences are ...
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0answers
71 views

Searching for image samples in order to create custom classifier

I am training a classifier of my own, specifically for detecting body arms. According to the training process I have to provide positive samples and negative samples, wich will be used in the ...
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1answer
269 views

MATLAB: Why my Pixel Indices are so different from that in Spatial Coordinates [closed]

The question is revised to make it more specific and constructive. I am doing imtransform, yet the xdata and ydata are very much different from that of size(output). [ output, xdata, ydata ] = ...
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2answers
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Training custom classifiers using trainCascadeObjectDetector

Is there any good documentation about training your own classifiers(with examples included) different from this one provided by MathWorks. Thanks in Advance
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What is the state-of-the-art method for dealing with illumination issues in background subtraction?

I have been struggling to find a well-cited approach to this. Essentially, I am experimenting with different background subtraction algorithms, but none seem to perform well when there are ...
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1answer
903 views

Properties of projected 3d points (to 2d), Principal component analysis (PCA)

This question is a little theoretical. Say I have 3 points that are bound within a certain 3D volume of some shape (i.e. box, cylinder, cone, etc). By using PCA, I find the most two dominant ...
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4answers
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Detect lanes from a filtered image

I am working on lane detection system and I would like some suggestions from you as to how to detect lanes from a filtered image which I got after performing certain operations. Firstly, I should ...
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1answer
555 views

Alternative to support vector machine?

I have to make comparison between 155 image feature vectors. Every feature vector has got 5 features. My image are divided in 10 classes. Unfortunately for using support vector machine i need at ...
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1answer
381 views

Object Classification using pyramid match kernel

I have been reading up on the pyramid match kernel as an alternative to using the bag-of-words model for object classification using a SVM. The bag-of-words model provides a model for transforming a ...
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1answer
11k views

Image processing and the Fourier Transform

I am trying to understand how and why the fourier transform is used in image processing / computer vision. Below is what I have gathered so far. Would my understanding of it be correct? If not, could ...
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1answer
2k views

How to relocate face points in opencv / face distortion?

I have to simulate facial expressions on a face image ( say open mouth ). For this I first extracted the facial feature points and found the corners of the lips. Now I need to deform the image by ...
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250 views

Evaluation of Keypoint Detector and Feature Descriptor Combos for Vehicle Detection

I am currently doing a research project into the effectiveness of different keypoint detector and feature descriptor combinations for the task of vehicle detection. At the moment I am using a SVM for ...
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1answer
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What is a good distance measure for matching SIFT descriptors depending on the distribution of their noise?

I have read some papers about distance measures like Euclidean, Manhattan or Chi-Square for matching gradient based image descriptors like those computed from the SIFT Algorithm (128-D vectors). Most ...
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1answer
1k views

How to calculate Noise and distortion of an image?

I need to make an application in iphone which needs to calculate noise, geometric deformation other distortions in an image. How to do this? I have done some image processing stuff with opencv + ...
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1answer
180 views

Recognizing hand-written archaeological signs

I have 75 images of handwritten signs from which I extracted 7 Hu moments and solidity features. How can I find similarities among them to train a classifier and predict the value? I thought SVM was a ...
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106 views

Phong Reflection Model Parameters

Question: Can anyone refer me the Phong reflection model parameters for a face image taken for web-cam? Details: I am doing 3D reconstruction of 2D images using 3D Morphable Model as in this paper ...
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2answers
281 views

Steps for recognizing hand written signs

What are the steps to built a system which recognizes hand written signs in an image and returns the most similar sign in Python? I know that depends on the image and many variables, but isn't there a ...
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2answers
294 views

Filter for Reducing Background Noise in Image

I have images where there is a lot of "black" background (few shades of black). (In many images at least half the pixels are background). I need to get interest points from the image, but because the ...
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1answer
322 views

best robust feature detectors for detecting similarities among archeological signs

I would like to implement edge detectors for creating a feature vector for archeological signs. Which are best features, algorithms to retrieve? That could be loaded in a Support vector machine for ...
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1answer
408 views

Is the Canny algorithm enough for creating a feature descriptor image for input to an SVM?

I retrieve contours from images by using the Canny algorithm. Is this enough preprocessing to have a descriptor image for input into an SVM to find similarities? Do I need other features like ...
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3answers
397 views

Gesture recognition using only simple techniques

I'm following a computer vision course and I have this exercise: write a program that, given an hand image, it can recognize if the hand is open, closed, in a punch, or holding an "ok" posture, using ...
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4answers
321 views

Any references for the trade-off between software and mechanics/optics in industrial machine vision systems?

I explain my question with a simplified example. I can design an industrial vision system for the automatic inspection of an item with these main requirements: the image of a good piece must be a ...
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2answers
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Digital image moments in plain English

I'm studying OpenCV and, in computer vision and image processing, people speak of blobs, contours, connected regions, and I sometimes hear the phrase "image moments". I know of an article on ...
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Looking for algorithm to extract line network from binary images [duplicate]

Possible Duplicate: Looking for algorithm to extract line network from binary images within LabView I would like to create a LabView VI that receives an input image and the RGB-color codes of the ...
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1answer
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Looking for algorithm to extract line network from binary images within LabView

I would like to create a LabView VI that receives an input image and the RGB-color codes of the powerlines depicted in the image. The output should (eventually) consist of id'd polygonial connections ...
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754 views

Using GavabDB for 3D face reconstruction from frontal image

Project: 3D face reconstruction Input: 2D frontal face Image Output: 3D face Reconstruction and expression simulation Platform: Matlab or Opencv cpp. I found out after study that 3D Morphable Models ...
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1answer
565 views

Safe Point Thinning Algorithm - How to?

I am relatively new to image processing and am working on a project that requires the thinning of binary images. In the literature, I've seen references to the Safe Point Thinning Algorithm(SPTA) ...
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2answers
943 views

Qualitative Evaluation of Interest-Point-Detectors and Descriptors in Computer Vision

I'm writing on a qualitative evaluation study of interest-point-detectors and descriptors. I've read all Mikolajczyk papers as well as most of the surves from Datta et al. etc. Now I'm implementing an ...
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450 views

STASM or AAM which is more efficient

I am working in face detection and recognition project. I am using STASM for face detction and locating face landmarks. On googling I found AAM (Active Appearance Model) and found that it is also used ...