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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Feature Matching Match Rate Between Two Images

I'm making an app which will match the input image with the images from the database. I'm using this code anyway: String path = Environment.getExternalStorageDirectory().getAbsolutePath(); Bitmap objectbmp =…
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How to find Relevent Features for Comparing Diagrams(Images)?

Currently we are doing a project on diagram comparison using SVM. Diagrams mainly include flow charts and block diagram.we are stuck on determining relevant features for training the SVM. The problem is that diagram and its components to be compared…
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SVM for character and digit recognition

just for scientific research and to compare with some other methods I am doing character and digit recognition on a single image. this is original image. after some processing my final image become like this. I've manually cropped all characters…
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OpenCV Bag of Words: Assertion failed (!_descriptors.empty())

I'm trying to create Bag-Of-Words so I can train the SVM later. I'm new with OpenCV so I used a code that I found on the Internet. The problem is that I have the following error: OpenCV Error: Assertion failed (!_descriptors.empty()) in add, file…
dephinera
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Extracting features using MB-LBP for multi-view face detection

I am working for multi-view face detection. I have two steps in developing face-detection, (1)decision tree makes decision of which classifier to run and (2) running a selected classifier for detecting the specific orientation of face. I have 9…
batuman
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Finding a rectangle and its corners in an image

I am building a machine for placing SMD elements. I'm almost finished, but I've got one problem. The elements that I'm placing must be placed in a specific orientation. I want to show the picked element to a camera from its bottom, so that my…
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DrawKeypoints in android using openCV

I wanna draw key points in OnCameraFrame, but i get a erro, can someone help me ? I put my code below: Code: MatOfKeyPoint points = new MatOfKeyPoint(); Mat mat = (Mat) inputFrame; FeatureDetector fast =…
NatsuDragonEye
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Cyclostationary Feature Detector: Performance doesn't vary with Change in SNR

I have Implemented Cyclostationary detector for spectrum sensing in AWGN channel in Matlab but I am getting vague result. As it performance doesn't vary with change in SNR. Its very strange result for me. I don't know what mistake I am doing in it.…
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Object matching using Feature Matching in Open CV

I am new in OpenCV. I have used template matching to match a template image in a big image. But using feature matching sometimes it is not matching. Size of my template is 40 X 40. Please help me in this. One thing which I want to know that if…
Anurag
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Display Keypoints on Image in Android - OpenCV

I'm trying display a image with keypoints detected. In my code, i get a list of key points, my i can't display the image on screen. I think that my problem is on converting the image to bitmap from MAT. What i'm doing wrong ? Here is my code: …
NatsuDragonEye
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OpenCV calculate time detection features

I'm trying to calculate the time that my program takes to detect the keypoints from an image. If in my c++ program I do it two times (with the same image) there is a huge difference between both. The first time it uses around 600-800 ms and the…
DavidGSola
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CBIR project suggestions

I'm trying to build an CBIR (content based image retrieval) project and for the first step I'm looking at a good feature. This should be invariant on several cues: scale rotation illumination and device, and I've not any database or previous…
user2614596
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FAST detector with circular array run so slow. Matlab (edit : remove circshift)

hello im working on FAST method using Matlab and it's run so slow in my notebook. this is the theory of my code FAST Detector. I know my code is ineffective and not good enough especially in the array part and loop. this is my code : EDIT : I remove…
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Comparing regions for similarity

I'd like to check one feature (The lower part of the RAI) if it does appear at the top of the given images. Occasionally, there may be some noises at the left or right of the images affecting the detection such as some vertical lines or the…
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Automatically Reorient and Crop Similar Images

I've been looking around for a while but have been unable to find someone describing exactly what I'm looking to accomplish. Currently, I have about 25,000 images of old typewritten documents that I am looking to build a database from. Originally, I…