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Questions tagged [edge-detection]

Edge detection is a tool in computer vision used to find discontinuities (edges) in images or graphs. Use this tag when asking about finding and manipulating edges or edge interaction.

Edge detection is a part of computer vision where the goal is to find edges in images. This often involves computing derivatives of the image with respect to the coordinates, because intuitively if the difference between two neighboring pixels is high, it is likely that there is an edge in the image. A popular edge detection algorithm is the Canny edge detector. Other edge detection algorithm includes Laplace & Sobel.

Discontinuities in image are likely to correspond to

  • discontinuities in depth
  • discontinuities in surface orientation
  • changes in material properties and
  • variations in scene illumination
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Extract single line contours from Canny edges

I'd like to extract the contours of an image, expressed as a sequence of point coordinates. With Canny I'm able to produce a binary image that contains only the edges of the image. Then, I'm trying to use findContours to extract the contours. The…
Muffo
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Applying the Sobel filter using scipy

I'm trying to apply the Sobel filter on an image to detect edges using scipy. I'm using Python 3.2 (64 bit) and scipy 0.9.0 on Windows 7 Ultimate (64 bit). Currently my code is as follows: import scipy from scipy import ndimage im =…
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Edge Detection method better than Canny Edge detection

Is there an Edge Detection Method that performs significantly better than the Canny Edge Detector ??
obelix
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Detect an object in a camera image in C#

I have an image, taken from a live webcam, and I want to be able to detect a specific object in the image and extract that portion of it to do some further processing. Specifically, the image would be of a game board, let's say for the purposes of…
Jon Grant
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Find the best Region of Interest after edge detection in OpenCV

I would like to apply OCR to some pictures of 7 segment displays on a wall. My strategy is the following: Covert Img to Grayscale Blur img to reduce false edges Threshold the img to a binary img Apply Canny Edge detection Set Region of Interest…
locorecto
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How can I use the latest version of Imagemagick on Heroku?

Heroku Cedar-14 stack currently runs a version of ImageMagick (6.7.7-10) that is nearly a year old: Running `identify -version` attached to terminal... up, run.8227 Version: ImageMagick 6.7.7-10 2014-03-06 Q16 http://www.imagemagick.org Copyright:…
Rob d'Apice
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Rectangle detection in image

I'd like to program a detection of a rectangular sheet of paper which doesn't absolutely need to be perfectly straight on each side as I may take a picture of it "in the air" which means the single sides of the paper might get distorted a bit. The…
tim
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OpenCV Canny + Watershed

I'm using a canny edge detection and a finding contours function (both OpenCV) to create markers for the watershed transform. Everything works fine but I'm not 100% satisfied with the results. The reason is that some edges are missing and therefore…
user667804
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OpenCV: Prevent HoughCircles method from using Canny Detection

I am using HoughCircles to detect a ball in real-time, but running Canny on my gray-scale image stream isn't creating all of the edges as it should. To remedy that, I am splitting the rgb image into it's separate channels, performing Canny on each…
Asher Johnson
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Canny Edge Image - Noise removal

I have a Canny edge detected image of a ball (see link below) which contains a lot of noisy edges. What are the best image processing techniques that I can use to remove these noisy edges without removing the edges belonging to the ball? Original…
Adam
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How to detect the Sun from the space sky in OpenCv?

I need to detect the Sun from the space sky. These are examples of the input images: I've got such results after Morphologic filtering ( open operation for twice ) Here's the algorithm code of this processing: // Color to Gray cvCvtColor(image,…
Larry Foobar
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How to segment blood vessels python opencv

I am trying to segment the blood vessels in retinal images using Python and OpenCV. Here is the original image: Ideally I want all the blood vessels to be very visible like this (different image): Here is what I have tried so far. I took the green…
Shalin Shah
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Having difficulties detecting small objects in noisy background. Any ways to fix this?

I am trying to make a computer vision program in which it would detect litter and random trash in a noisy background such as the beach (noisy due to sand). Original Image: Canny Edge detection without any image processing: I realize that a…
user3377126
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Line detection in image

I am new to image processing and I was trying to detect vertical lines using this code- image=imread('benzene.jpg'); BW = im2bw(image); w1=[-1 2 -1 ; -1 2 -1 ; -1 2 -1]; g=(imfilter(double(BW),w1)); g=abs(g); T=max(g(:)); g=g>=T; imshow(g); This…
Noober
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Sobel Edge Detection in Android

As part of an application that I'm developing for Android I'd like to show the user an edge-detected version of an image they have taken (something similar to the example below). To achieve this I've been looking at the Sobel operator and how to…
greenie
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