Questions tagged [feature-detection]

Feature detection is a process in computer vision that aims to find visual features within the image with particular desirable properties. Detected features can be points, image regions or continuous curves in the image. Interesting properties can include invariance to noise, perspective transformations, or properties interesting for specific usages (e.g. tracking).

Feature detection is a process in computer vision that aims to find visual features within the image with particular desirable properties.

Detected features are some subsection of the image, and can be:

  • points (e.g. Harris corners)
  • connected image regions (e.g. DoG or MSER regions)
  • continuous curves in the image

Interesting properties can include invariance to noise, perspective transformations and viewpoint changes (camera translation and rotation), scaling (for use in visual feature matching), or properties interesting for specific usages (e.g. visual tracking).

Important information about visual features can include:

  • coordinates in the image
  • radius of the visual feature
  • scale (octave) of the image on which the feature has been extracted

After detecting the feature with some feature detection algorithm, it is usually described by a descriptor vector (several known descriptors are used today) for the purposes of visual feature matching, while the feature's position in the image can be used directly for application in tracking.

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OpenCV 2.4, Python - Retrieving the laplacian from a SURF keypoint

I'm using OpenCV 2.4 to extract SURF features and need the laplacian value of each keypoint for the matching process. I didn't have a problem with this when I was using OpenCV 2.3. In OpenCV 2.4 cv2.SURF() doesn't work so I have to resort to doing…
Kkov
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Passing "List objectKeypoints" jobject to Vectorin native Code

I'm currently working on an android application. On java side I pass a List objectKeypoints to native Code. But how can I convert this jobject on native side to Vector objectKeypoints for further processing. Exaample: Java Side…
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How to implement a method to extract multiple features from a binary image

I am implementing a simple computer vision system in java. It extracts shapes from an image. Which are generally circular or oval in shape. I have it working to the point where it can create a binary image consisting of only the features I want to…
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Which Feature Selection Techniques for NLP is this represent

I have a dataset that came from NLP for technical documents my dataset has 60,000 records There are 30,000 features in the dataset and the value is the number of repetitions that word/feature appeared here is a sample of the dataset RowID …
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How to select the best features from all features when data sets don't have target variable where feature importance can change over time?

My data sets have 200 features and 500 rows. from that I must select the best 30 features that can be used in the model instead of all 200 features for the sales prediction model, but the feature importance can change over time. Interesting thing is…
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How can I improve the quality of the recognition of playing cards?

I am trying to build a classification of playing cards. The goal is that I use an image of a playing card as input and the script then outputs whether it is a playing card and if so, which one. For this I have written the following comparison…
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How can an @supports rule support name of animations in this statement?

I found this CSS on a page in the W3C and I don't know how it makes any sense, specifically the animation name part: @supports ((transition-property: color) or (animation-name: foo)) and (transform: rotate(10deg)) { //…
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What is compared when a CNN learns a set of features during backpropagation?

I am relatively new the subject and have been doing loads of reading. What I am particularly confused about is how a CNN learns its filters for a particular labeled feature in a training data set. Is the cost calculated by which outputs should or…
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Feature.exe: 0xC0000005: Access violation reading location 0x0000000000000000

I am trying to detect and extract image feature using DynamicAdaptedFeatureDetector, but i am receiving Access violation error. The complete error is: Unhandled exception at 0x000007FEE08AB89A (opencv_features2d2411d.dll) in Feature.exe: 0xC0000005:…
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Extracting Features from the image manually

I am working on image classification problem. How to find out specific features from the image manually that will help to build a DNN? Consider an image of a man talking on phone while driving for classification as distracted.
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In video processing, is the z-coordinate the frame number?

I'm trying to perform some basic action recognition using the KTH dataset. I'm using the 3DSIFT feature extractor from UCF link. Which extracts a SIFT descriptor from a given x, y and z coordinate. For feature detection I am using selective-STIPS…
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How to achieve the robustness while detecting features from a continuous video stream

I have been working with object detection from a video but the problem is, I cannot detect the same features in two consecutive frames. I am using SURF with Brute Force Matcher and knnMatch. Ratio has been set to 0.5 for good matching
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Extracting Feature from an Image - suggestions for best approach?

I am currently learning computer vision and I would like to extract the onion from the image. What would be the best approach to do this? I attempted a thresholding approach to detect white colour by breaking down the image into its R,G,B channels,…
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iOS: how to detect if an image has a certain RGB colour

Is it possible to detect if an image captured with the camera roll has a certain RGB colour in it?
mm24
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Modernizr to check for css3d transforms and flexbox include ie10

I'm trying to figure out what build of modernizr I need to use in order to detect support for css3d transforms and flexbox in a way to also allow ie10 to pass. Having looked at http://caniuse.com/#search=flexbox and http://caniuse.com/#search=3d…
Ilja
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