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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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OpenCV Python, filter edges to only include those connected to a specific pixel

I've got a script that uses the Canny method and probabilistic Hough transform to identify line segments in an image. I need to be able to filter out all line segments that are NOT connected to a specific pixel. How would one tackle this problem?
tpubbsGIS
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Python irregular x,y data to contour plot on original domain

I have file containing points under the columns "x-cord", "y-cord", "value". These are irregularly spaced. I am trying to make a contour plot of "value" and overlay this over the original domain. I gave up trying to do this in both pgfplots and…
1QuickQuestion
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How to improve detection of Probalistic Hough-Lines-Transform?

I'm trying to detect a clock hand in a video of an analogue display and extract the value it points to. I'm using Python with OpenCV for this. What I essentially do is: I'm using a Gaussian Blur to lower the noise in the current image. I use Canny…
Yggdrasill
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Find thick and odd shapes on an image

I am coding a specific edge detection algorithm. The image is black and red as given below. I am trying to extract red points that make a horizontal or vertical line and trying to get rid of anything that doesn't make a line shape. Some odd shapes…
A Doe
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Extracting foreground objects from an image to run through convolution neural net

I am new to computer vision and image recognition. For my first CV project I am developing a tool that detects apples (the fruit) in images. What I have so far: I developed a convolution neural net in Python using tensorflow that determines…
user2836816
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Recognize Text in images using Canny Edge detection in Opencv

I'm trying to extract text from colored background images. One approach that I'm trying is edge detection. Using that I convert the original image to a image that I can work with. This will eliminate all the color in the image leaving only the…
Tharindu Senanayake
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Looking for edges, algorithms optimization

I have straight-forward functions for identifying edges in THREE.Geometry(). var edges = []; for(var i = 0, l = geometry.faces.length; i < l; i++) { findAdjacentFaces(i, edges, geometry); } function findAdjacentFaces(face_, edges_,…
VVK
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Given a coordinate and color, how to programatically determined a contiguous region of that color?

I'm using Ruby and RMagick to process an image, but the question is language agnostic... I'm basically processing an image of tabular data and figured one of the easiest ways to determine a cell is to detect a contiguous area of white (or whatever…
Zando
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Convert imshow object to image directly for edge detection?

Is there a way to convert the imshow object to an image directly in python 2.7 code? I'm trying to obtain the spectrogram of a wav file and use the image to detect edges in it. I have the code to get the spectrogram, I have the code to detect…
Dinesh
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c# detect points of polygon in black/white image

I have to detect all the points of a white polygon on a black background in c#. Here is an image of several examples. I wouldn't think it is too difficult, but I am unable to detect this properly with all the variations. My code is too much to…
dan
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Which method do you suggest for my segmentation task post-processing step?

I am developing a neural framework for instance segmentation. At the moment I have quite reasonable outcome (probability map) as follows: Input image: Corresponding probability map: As you may noticed, the outcome has blurred boundaries while I…
Ali Sharifi B.
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Edge Detection in OpenCV

We have written a code for edge detection in OpenCV java where the background for the image would be plain white to increase accuracy. We have added the following functions for the edge detection part: Imgproc.GaussianBlur(im, im2, new Size(0,0),…
Ajinkya Upasani
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Draw contours correctly on the image (OpenCV/Python)

I am trying to draw contours around my test image. I am using canny edge detection in the background. The findContours method works fine for my image but when I try to do drawContours method on that image. It does not show anything. Here is what I…
Tasdik Rahman
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matlab - line equation to 2D matrix with values of 1 and 0

As the title says, I want to covert a line(or any equation) to 2D matrix. For example: If I have a line equation y = x, then I want it to be like: 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 and the length of rows and…
Yonggoo Noh
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finding rectangles in a pcb using python

Is there any way to find rectangles in a pcb board using python? My goal is to find the pcb components. I tried to smooth the picture and then apply cunny edge and contour detection but the only correct contour that i managed to find is the contour…
Eugene Moush
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