Questions tagged [edge-detection]
Edge detection is the process of identifying points in an image, where image brightness changes sharply.
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Seeing edges where there are no edges
The human eye is able to detect a square inside the square in the following two images, even though there are no obvious edges and no obvious local changes in the density of dots.
GPT4o believes to ...
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Detecting a large horizontal band in the center of an image
I have a small (228x228) grayscale image that I have created by segmenting the original image and converting it to grayscale after applying colors to the segment. I want to know possible approaches I ...
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Detect Longest Vertical Lines (Edges) in an Image
I have a task in image processing, which need to detect vertical lines from matrix. For example, there is a pair of white and black vertical lines segmenting the picture below. I need to find it. So I ...
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Chebyshev filter analog in computer vision?
Looking at the basic characteristics of a Chebyshev Filter, I was wondering if there were any analogous type filters in Computer Vision? The way that it can minimize the error between the idealized ...
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OpenCV 2 Connect Incomplete Contours edges
I have to connect the unfinished edges of the contours in the red color bounding box.
I used distance transform, watershed, and morphology, but still, edges are not connecting.
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Separating dominoes pieces from one another and counting them
I Have a picture of Dominoes on a table, which is noisy.
I am trying to do the following:
removing the background.
counting how many dominoes pieces are there.
identifying what each piece represent.
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A mathematical justification of discontinuity detection using STFT
I'm trying to detect rapid changes in a one-dimensional signal say $[0,1]\ni t \mapsto f(t) \in [-1,1]$. By rapid changes, I mean corner points, edges, or sharp transitions at a point for example the ...
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Segment Image of Small Elements on Neutral Background
I have a 8 bit gray level image where if the value = 122 it means no information, value = 0 means highly negative, and value = 255 means highly positive.
I want to connect as many positive information ...
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Removing tessellating interference patterns from images
The microscopy image below is corrupted by an irregular checkerboard-like grid. I attempted running 2D-FFT on the image, but was unable to isolate the frequencies which cause the pattern.
How would I ...
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Segmenting dark spots from a light background?
I need to perform automatic segmentation of dark blue spots on light yellow paper. Here's a very simple example:
In this case, a simple threshold based on hue or brightness works well. But here are ...
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How many directions are there in the Non Maximum Suppression part of the Canny Edge Detector
In the Non-maximum suppression algorithm, each pixel has a total of 4 directions since there are 8 neighboring pixels. But why there is not 8 directions instead, please? I see below there are 8 ...
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Why is Envelope noisy even after filtering and achievement of SNR gain (-6dB SNR to 14dB snr)?
A noisy signal with 500 MHz bandwidth, with negative SNR, when filtered to 6 MHz bandwidth, should attain a theoretical SNR gain of 20 dB. So if the original signal has -6 dB SNR, after filtering we ...
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Interpreting results of Sobel Edge Detection
I am implementing A No-Reference Perceptual Blur Metric paper.
Somewhere in the prep steps they mention the use of vertical Sobel filter for finding vertical edges.
The algorithm is summarized in Fig....
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Removing dark borders in Image Stitching for Panorama
I am working on a Matlab code for panoramic image stitching for multiple image frames and getting satisfactory results however there are always dark regions surrounding the stitched images as ...
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Implementation of Deriche filter
The Canny edge detector is expressed by the derivative of the Gaussian. Its practical implementation involves the Gaussian filter, then the Sobel filter to calculate the gradient in both directions. ...
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