All Questions
Tagged with edge-detection algorithm
48 questions
0
votes
0
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85
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How to recovering sharp edges on a triangular mesh
I need some suggestions to be able to recover or recreate the edges in my mesh.
The mesh comes from a 3D scanner and the edges are therefore not well defined.
I implemented an edge detection algorithm ...
0
votes
1
answer
707
views
what are the common used fast Edge Detection Algorithm using GPU shader(glsl, hlsl, not CUDA)?
what's the fastest Edge Detection Algorithm using GPU shader(glsl, hlsl, not CUDA)?
just fragment-shader, just image-processing, no matter the image is colorful or gray
color buffer with normal ...
- 133
0
votes
0
answers
284
views
Is there any differentiable computation that maps the edge map into 2d coordinates of edge points and use it as a part of deep learning model?
I am doing a task where I use the Canny edge detector to compute an edge image which has white pixels representing the edge, and then I will need the coordinates of the these edge pixels in the image ...
- 1
0
votes
1
answer
114
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Refine an algorithm to locate the extrema of an object represented by a 2-d matrix of zeros and ones
Note: Not looking for code here, just an algorithm as I am stumped not on implementing a solution to this problem but on finding out what the solution is.
I have a large 2-d array that I created from ...
- 140
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0
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3k
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how to detect the rising edge of the signal (the rising edge consists of several points)?
I have a signal in
and I want to detect the rising edge of the signal and obtain a curve which has the peak point in the position of (x=147), I have tried to make difference of the signal, but the ...
3
votes
0
answers
371
views
Finder pattern for detecting image alignment markers
I am looking for an algorithm that can detect image alignment markers similar to the way QR codes use square markers on 3 corners to align and orient. I intend to use this solution to perform image ...
- 61
0
votes
1
answer
522
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Remove outer hull of 2D scatterpoints in Python
For my project i use 2D images from a telescope. The outer border of each image is known to be oversatured with points due to telescope malfunction. Therefor i want to extract the points that make up ...
- 55
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0
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73
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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 ...
- 301
0
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3
answers
338
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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); }
...
- 445
2
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0
answers
1k
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Is there a way to determine the length of edges in images under edge detection algorithms using OpenCV?
I am relatively new to OpenCV, but I have a question. I am interested in trying to figure out a way to take my image that have already been implemented by a color quantization algorithm and determine ...
- 255
2
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0
answers
2k
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Need a geometric edge/crease detection method
I am experimenting with a primitive rendering style (solid colors with highlighted edges/creases) for an open-source game I contribute to. The world geometry is fairly simplistic, and is mostly ...
- 33
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votes
1
answer
761
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Edge Detection Algorithm with Processing (Java)
i want to code an algorithm, that can do an edge detection for an image.
I already have a part of the code, which detects all edges in horizontal way.
Example picture:
But i need an edge detection in ...
- 87
4
votes
0
answers
250
views
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 ...
- 14k
0
votes
1
answer
777
views
MATLAB, algorithm for free surface detection in bubbly flow
I am trying to figure out an algorithm for detecting the free surface from a PIV image (see attached). The major problem is that in the flow under consideration gas bubbles are injected into the fluid,...
- 1
1
vote
0
answers
93
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Similar (not duplicate) image detection
I've been working on how to sort images by how similar they are (not looking for duplicates), I've tried pHash and other hash algorithms, but I feel like what I need is a way to detect similar edges (...
8
votes
4
answers
1k
views
Binary Image "Lines-of-Sight" Edge Detection
Consider this binary image:
A normal edge detection algorithm (Like Canny) takes the binary image as input and results into the contour shown in red. I need another algorithm that takes a point "P" ...
- 2,512
17
votes
6
answers
18k
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Edge detection for image stored in matrix
I represent images in the form of 2-D arrays. I have this picture:
How can I get the pixels that are directly on the boundaries of the gray region and colorize them?
I want to get the coordinates ...
user4632747
-2
votes
1
answer
542
views
need algorithm to find edge and boundary of matrix members
I have a 16X16 matrix , which contain members from 0,1,2,3, i want to know which algorithm should i use to find the boundary's between members to show the grouping, in the other word, with which ...
-1
votes
2
answers
1k
views
Find vertex from a object by using vertex detection
I would like to find all vertex (e.g. return x, y positions) for the black object.
I will use Java and JavaCV to implements. Is there any API or algorithm can help?
Sorry for not enough reputation ...
- 43
0
votes
1
answer
110
views
Graph search algorithm without starting point
I have an edge map of a scene and would like to extract the edge which best separates the sky and terrain. This seems to be well framed as a graph traversal problem. However, popular search algorithms ...
- 1,434
0
votes
1
answer
199
views
Matching photographed image with screenshot (or generated image based on data model)
first of all, I have to say I'm new to the field of computervision and I'm currently facing a problem, I tried to solve with opencv (Java Wrapper) without success.
Basicly I have a picture of a part ...
- 193
0
votes
1
answer
1k
views
MATLAB - Find local maximum and minimum of an edge map (row-wise)
I'll start off by saying I'm new to MATLAB, and this is the first time I'm trying an application related to image processing.
I'm building a MATLAB library (which is to be used in a Windows Phone ...
2
votes
1
answer
701
views
Supposed easy edge detection in MATLAB
I have the following image: and I'd like to detect a contour of the note which is intuitionally seen easy, but when I try to do it, it actually isn't that easy.
For quick prototyping I started using ...
- 10.2k
1
vote
1
answer
279
views
Image comparison of HD and SD images using Java
I have a database containing both the SD and HD version of same set of images. Problem is that their names are different from each other.
For example an image of a flower in SD has a name greatflower....
- 411
1
vote
1
answer
568
views
What is the purpose of the hypotenuse in the sobel edge detection algorithm?
I understand that you filter each pixel by a horizontal and vertical matrix that gives a horizontal and vertical gradient. The gradients represent the difference in color along their respective axis. ...
- 3,650
1
vote
1
answer
2k
views
Canny edge detection algorithm - implementation problems
I am trying to implement Canny Edge detection algorithm and I've encountered some problems along the way. I think I understand every step of Canny edge detection, but when compared to results given by ...
- 13
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1
answer
2k
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Practical way of setting Canny edge detection algorithm parameters automatically
Canny edge detector is often used in many image processing tasks. However, in order to obtain a descent edge detection map carefully setting its parameters is very important. Based on my experience ...
- 11.7k
3
votes
1
answer
721
views
simple straight lines detection algorithm
I'm looking for a simple algorithm for finding straight lines on the image. Not necessarily fast, just a working concept. I've done my homework and already found several approaches to the problem (e.g....
- 745
7
votes
1
answer
5k
views
Time complexity of Canny edge detector
I am currently writing a research paper about a new steganography algorithm. I have used canny edge detector at some point in my algorithm. In the paper I need to write the time complexity of the ...
- 5,647
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1
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5k
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Scaling Laplacian of Gaussian Edge Detection
I am using Laplacian of Gaussian for edge detection using a combination of what is described in http://homepages.inf.ed.ac.uk/rbf/HIPR2/log.htm and http://wwwmath.tau.ac.il/~turkel/notes/Maini.pdf
...
- 2,021
6
votes
1
answer
1k
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Can't get clean output in my MATLAB implementation of Canny-Deriche
My code so far is:
function imgg = derichefilter1(x, k, a, b, c)
osize = size(x);
x = double(x);
a = double(a);
b = double(b);
c = double(c);
k = double(k);
y1 = zeros(osize(1),osize(2));
y2 = zeros(...
- 1,314
1
vote
1
answer
1k
views
Scanline Algorithm
I am stuck in the midway(or at the start you can say) while implementing scanline algo.
I follow parity test i.e.,
for each scanline
edgeCnt = 0;
for each pixel on scanline (l to r)
if (oldpixel-...
- 21
3
votes
3
answers
544
views
Find inner geometry from edges
First I am not sure which keywords to use for this and I think I am probably using the wrong ones to google about it, so if someone could give me any hint it would be much appreciated.
My problem is ...
- 3,517
4
votes
2
answers
2k
views
detect edge with certain curvature
I am trying to find edges in an image that have a certain curvature: the lighter side of the edge should be the convex side.
The edges itself are no problem with sobel or canny, but I do not know how ...
- 13.8k
5
votes
1
answer
12k
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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 ...
- 483
8
votes
3
answers
6k
views
Find the maximum number of edges in the graph
There are 'n' vertices and 0 edges of an undirected graph. What can be the maximum number of edges that we can draw such that the graph remains disconnected.
I have made the solution that we can ...
- 5,451
0
votes
1
answer
112
views
Region Sets From Boundaries
I have an elevation map represented by a 2D array of floats.
There are regions of this map whose edges I have contained in a single vector which contains a list of the edge cells (identified by their ...
- 60.7k
1
vote
2
answers
325
views
Where to find materials about edge detection and which is good for virtual wardrobe application?
I am trying to build an application called virtual wardrobe where I am planning to capture the image of a human and then allow him to select different clothing and instantly see his virtual image ...
- 392
1
vote
1
answer
163
views
Algorithm for finding the edges of an unknown # of shapes
I'm looking for an efficient algorithm that can give me all the edges of a random shape. I can write one, but if anyone knows of an existing solution that may be optimized, it would be appreciated as ...
user578895
0
votes
2
answers
3k
views
Find all non-overlapping polygons in a list of edges/vertices
I have a list of edges and a list of vertices. Each edge references two vertices, each vertex maintains a list of edges.
I want to find all non-overlapping polygons produced from this graph.
An ...
- 4,363
15
votes
2
answers
2k
views
Algorithm for labeling edges of a triangular mesh
Introduction
As part of a larger program (related to rendering of volumetric graphics), I have a small but tricky subproblem where an arbitrary (but finite) triangular 2D mesh needs to be labeled in a ...
- 8,001
4
votes
6
answers
9k
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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 ...
16
votes
1
answer
21k
views
How to use Chamfer Matching algorithm for finding 'Similar Images'
I would like to ask for more information on how Chamfer Matching algorithm (an edge matching algorithm) can be used to find 'similar' images. I would like to know if it is possible to place a 'score' ...
- 503
1
vote
3
answers
353
views
Managed code (C#) vs Matlabs and C++ for speed
I am about to start developing an edge detection system (once I've read through a couple of books, which I'm doing so at good speed), but one thing I am wondering is the speed of an app like Matlabs (...
- 67.1k
8
votes
3
answers
7k
views
Algorithm to implement a lasso selection tool?
I am developing a Mac OS X application which, as part of it's UI, will display many visual elements in it's main view which can be selected. These elements can be positioned really anywhere within the ...
- 1,034
1
vote
2
answers
2k
views
Resources about Shen Castan algorithm
I have started some simple project about Text Detection in images. And one of steps in solving this problem is implementation of Edge detector. I wanted to implement Shen Castan, because it gives ...
- 3,288
4
votes
3
answers
5k
views
Canny Edge Detector in C
I am looking for a bit of clarification on how the algorithms implemented in Canny edge detection - Wikipedia entry - work. It seems pretty straightforward to perform noise reduction using a 2D ...
- 6,469
17
votes
4
answers
5k
views
Best articles to start learning about edge detection/image recognition
I am involved in a personal project which will require pretty extensive knowledge of edge detection and image segmentation/object recognition.
I know the importance of planning/understanding before ...
- 67.1k