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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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Detect U Shaped Edges in an Image

I'm trying to detect the location of a fingertip from an image. I've been able to crop out a region in the image where it must have a fingertip, and extract the edges using Canny Edge Detector. However I'm stuck. Since my project description says I…
Feverbeaver
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Adjusting the threshold in Canny edge algorithm

I wanted to try my hand at text recognition, so i've used opencv to trace out the edges and c++ to find slopes, curves etc, the edge algorithm works well on big and uncluttered sets of characters but when it comes against small printed text or text…
Gambit King
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Crop image after selecting area using edge detection in android

I want to automatically select area of the page to crop later. I thought edge detection might be useful and used canny edge detection to find edges of the image. Now I have this image! but I've no clear idea to select area of the page as a…
chAmi
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Opencv Edge extraction

I have an image and I want to create an edge histogram. I divide the image into 1100 image-blocks and try to find edge and its direction (horisontal, vertical, 45° diagonal, 135° diagonal or nondirectional) in each block. How can I extract that…
user101375
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Differences between 'imfilter' and 'conv2' [MATLAB]

I use this both function to find edges on a scale. You have a input image, you apply a mask (for ex. prewitt) to the input image, and get the resultant pic. mypic = imread('examplepic.jpg') hy = fspecial('prewitt') yimfilter = imfilter(mypic,hy) %…
user981227
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Remove image background so that only the logo (usually some text) remains as png

I would like to extract logos from golf balls for further image processing. I have already tried different methods. I wanted to use the grayscale value of the images to locate their location and then cut it out. Due to many different logos and a…
SchmidtiT
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Top head detection from overhead camera

I have a camera set up on a ceiling , capturing people standing in line. I need to count the amount of people. Currently I do that with background subtraction and Hough transform. The detector works well for contrast heads, but if hair color is…
user923744
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How to connect disjointed lines or edges in images?

I am currently working on lines extraction from a binary image. I initially performed a few image processing steps including threshold segmentation and obtained the following binary image. As can be seen in the binary image the lines are splitted…
Thomas
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Detect circles and ellipses from binary image when the shapes are not closed

I try to detect grape berries in a grape bunch (which usually have a shape of circles and ellipses) in RGB images. few examples of my dataset: I don't care about detecting all the berries, but I do want the ones that will be detected to be as…
Edo Wexler
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Execution failed for task ':simple_edge_detection:externalNativeBuildDebug'

i am using simple_edge_detection library from here : https://www.flutterclutter.dev/flutter/tutorials/implementing-edge-detection-in-flutter/2020/1509/ CMakeLists.txt cmake_minimum_required(VERSION…
Mansi Bhatt
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How to convert binary grid images to 2D arrays?

I've got some images of binary (black and white) grids that look like this: Now, I want to convert such images to regular 2D NumPy arrays, where each cell must correspond to 0, if the source cell is white (or uncolored) and 1 if the cell is black.…
s0mbre
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How can I get the edges of low contrast image in opencv python

I'm trying to get the edges of this object from a TEM(microscope) image and the problem is that the contact is low especially in the upper edge, I tried several things thresholding, contrast equalization... but I wasn't able to get the upper…
Khalil.h
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EmguCV Cut Face+Neck Skin Only And Save New Image

In my app, I will input a human image and I want to get the face and neck only of that person as output in separate image. Example: Below image as input:(Source:http://www.fremantlepress.com.au) And I want to get the up image as output: I want…
Foyzul Karim
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Does cv2.Canny() perform a Gaussian blur?

I know it's important to apply Gaussian blur to an image before using Canny to detect edges. My question is: does cv2.Canny() do Gaussian blur on its own or it is necessary to apply cv2.GaussianBlur() before cv2.Canny()? The documentation isn't…
DLopezG
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Opencv Sobel edge detection for diagonal (up-right 45deg, upleft 135deg)

I am having issue with opencv's Sobel edge detector. From its documentation it seems to work only for horizontal and vertical direction edges (by specifying 0,1 or 1,0). Has anyone got idea how to get the diagonal edges 45deg and 135deg with cvSobel…
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