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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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Determining Similarity of Edge-Detection-Processed Images

I was hoping that I could achieve some guidance from the stackoverflow community regarding a dilemma I have run into for my senior project. First off, I want to state that I am a novice programmer, and I'm sure some of you will quickly tell me this…
Mike D.
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Display only 45 degrees line in an image

I want to detect lines in an image which is at 45 degrees only with respect to the origin. I have to do it with 3x3 convolution only. I have solved it such that all lines at 45 degrees are removed and everything else stays(inverse of what I want).…
Asim
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What is the difference between a Line and an Edge in image detection?

We have been learning about methods like Sobel and Roberts' convolution matrices to detect edges within images, extending to the Canny method to clear them up. But now, we are learning about 'Line' detection, as opposed to 'Edge' detection - with…
j panton
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Edge detection on C#

I have a black and white image like this (color overlays are mine, and can be removed): I need to figure out the edge of the hand shown, how can I do that? My current algorithm: List edgePoints = new List(); for (int x…
Malfist
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Canny edge detector for Android -- StackOverflow on recursive function

I'm working on an augmented reality app for Android. I'm implementing Tom Gibara's canny edge detector class and have replaced BufferedImage, which is not supported by Android, with Bitmap. The method "follow" (posted below) is causing a…
Allison
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Opencv hysteresis Thresholding Implementation

I have binary image of edges computed from Phase and magnitude (monogenic signal) , and I want to apply hysteresis thresholding in OpenCv. Unfortunately i couldnt use it as its implemented within Canny edge detection in opencv library. I want to…
aditya sai
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detecting multi color document with OpenCV4Android

I am new to OpenCv with Android.I am trying to make an application which auto detects documents using OpenCv - 2.4.13 . In my app, there is a functionality of detection documents (like a Scanbot app) and then prospect it to document. So, far I am…
ImLearning
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OpenCV - canny edge detection not working properly

I am new to OpenCV with Android. I am currently working on document detection demo app. What I did so far is as below: Original image -> Gray scale image -> GaussianBlur -> Canny edge detection -> finding contours -> draw Contours I am able to…
ImLearning
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Detecting individual boxes in W2 with opencv - python

I've done extensive research and cannot find a combination of techniques that will achieve what I need. I have a situation where I need to perform OCR on hundreds of W2s to extract the data for a reconciliation. The W2s are very poor quality, as…
keyoung1
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Detect quadrilateral from grayscale image

I'm looking for a method to detect quadrilateral based on grayscale images like this. The actual solution I've made is based on HoughLines and has two problems: As it is a parametric method, small changes on the input image gives me two different…
Ghilas BELHADJ
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What is the fastest way of edge detection?

I am thinking of implement a image processing based solution for industrial problem. The image is consists of a Red rectangle. Inside that I will see a matrix of circles. The requirement is to count the number of circles under following constraints.…
Chathuranga Chandrasekara
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Matlab image segmentation by using line edges

I want to segment the image to 3 parts like figure 2 shows. The first work I have done is using canny edge detection to extract edges like figure 3 shows using code below. rgb = imread('Camera_205.png'); I = rgb2gray(rgb); imshow(I) figure BW =…
SimaGuanxing
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Edge detection on pool table

I am currently working on an algorithm to detect the playing area of a pool table. For this purpose, I captured an image, transformed it to grayscale, and used a Sobel operator on it. Now I want to detect the playing area as a box with 4 corners…
PKlumpp
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Very Simple Edge Detection

I have a simple, high-contrast, black & white video image on which I need to find the X value of a vertical edge and the Y value of a horizontal edge. I also need to know the direction of the edges (white->black or black->white). There will…
Tergiver
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Find edges (border of rectangle) inside an image

I have an image of a sticky note on a background (say a wall, or a laptop) and I want to detect the edges of the sticky note (rough detection also works fine) so that i can run a crop on it. I plan on using ImageMagick for the actual cropping, but…
navinpai
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