The tag has no usage guidance.

learn more… | top users | synonyms

1
vote
1answer
20 views

How to set threshold value for Hough Transform

I am new to Computer Vision, I am writing my own code for Hough Transform I have found the following algorithm: Algorithm: ...
3
votes
1answer
70 views

How to calculate particles sizes for spheric particles with overlapping and superposition? (Example image included)

I'm trying to automatically calculate particles sizes histogram for images like this one: Common threshold and segmentation doesn't seem to work. What filters and algorithms do you suggest to be ...
1
vote
1answer
55 views

how to detect two parallel lines in a binary image with MATLAB

I am working on license plate detection using hough transform. I am trying to detect the horizontal and vertical edges and then to find the parallel lines. My ...
0
votes
0answers
29 views

How to detect malformed-ellipse-alike objects?

I need to process a stack of ultrasonic images, where there is mostly a lot of noise to see, but I need to extract specific objects that look for example like this: Here is an example from ...
0
votes
0answers
77 views

HoughCircles finds anything but circles

I use emgucv (an opencv wrapper) to find circles in image. To test it, I drew a circle on image in photoshop. I used HoughCircles algorithm with a very small distance between circles' centers and ...
0
votes
0answers
25 views

Generalizing Matlab Hough Function

I am trying to modify the MATLAB hough() function so that it handles grayscale images. for that I started with openening the file ...
0
votes
2answers
79 views

Difference between MATLAB hough and my implementation

I am trying to recreate MATLAB's hough function with mine. My code follows ...
0
votes
0answers
66 views

Completing an image edge using MATLAB

I'm trying to complete the right edge of the rectangle in the following image: The approach I've tried involves running a Sobel filter for edge detection on the image rotated by 45 degrees, ...
0
votes
2answers
189 views

How to extend hough lines over the image space

I need to extend lines over the image space. I used Hough transform to finde vanishing lines, but i need to get lines longer and see where is vanishing points. How can i do it? Please help. This is ...
0
votes
0answers
190 views

How to get accurate line detection using Hough Transform?

I am currently working on my final year project for lane detection.My biggest problem now is that the Hough Transform method does not accurately detect the line.It just randomly detect line somewhere ...
0
votes
1answer
412 views

In opecv function Hough circles how does parameter 1 and 2 affect circle detection and how can i adjust them to increase accuracy??

http://docs.opencv.org/doc/tutorials/imgproc/imgtrans/hough_circle/hough_circle.html I'm using houghcircle function to detect circle.Problem is if i set minimum radius to null it detects wrong center ...
0
votes
1answer
959 views

Circle detection opencv

I Would like an explanation of the parameters for opencv's HoughCircles function. I'm new to image processing in general and I have recently started using opencv. ...
0
votes
1answer
358 views

Hough Transform in Matlab without the built-in function

I want to implement Hough transform on image without using inbuilt function. Some papers say that the image is first flipped before applying Hough transform. I do not understand how Matlab is doing ...
0
votes
1answer
364 views

Shape recognition, hough transform

I'm trying to match a picture saying "this is ducks, this is towers" by giving votes from the hough transform of a picture. I've found this article ...
1
vote
1answer
1k views

Detecting text lines in image by means of Hough Transform

In my Android App,I have to detect text lines in images.I want to use Hough Transform to detect lines.You can see an image below: I got edges in image by ...
5
votes
2answers
898 views

Why is the Canny edge detection used instead of Sobel/ Prewitt edge detection before Hough transformation?

I know that for the Hough Transform to work on an image, it needs to be a binary image. To convert from a grayscale image, an edge detection algorithm should be employed. I notice that people always ...
2
votes
0answers
68 views

How to quickly calculate all the line segments when their coordinate in the Hough transform is given

Hough transform is a very powerful tool to find dominant straight lines in a black-and-white image. A very common practice of analyzing Hough transform result is to find some local maximum points in ...
1
vote
3answers
804 views

Hough lines and Convex Hull methods give jagged lines

I need to do a perspective transformation on an image section from newspaper, here the girl's image. The section's coordinates are given as rough estimates. I need to find the boundary of the section ...
0
votes
1answer
256 views

Edge following using Hough transform

Im trying to improve an edge following algorithm developed by some students who did a projekt at my work. The algorithm is supposed to make an robot follow a line with use of an camera. Their approch ...
1
vote
2answers
7k views

Detecting lines with houghlines in matlab

I have This image which is basically made of sloped lines (almost horizontal and parallel) I tried exactly the code in matlab documentation to detect those lines (except the rotation part) but I ...
1
vote
1answer
67 views

Confusion about hough transformation for ellipse

I saw the following sentence from Feature Extraction & Image Processing, 2nd Edition $$ x = a_0 + a_x\cos(\theta)+b_x\sin(\theta) $$ $$ y = b_0 + a_y\cos(\theta)+b_y\sin(\theta) $$ This ...
2
votes
1answer
4k views

Influence of image size to edge detection in OpenCV

I need to scan an image in OpenCV and obtain the lines. For this I use the canny edge detector and then the propabilistic Hough transform, with which I actually get the lines. The problem now is that ...
3
votes
1answer
417 views

Improving the performance of the Hough transform

I have just started doing image processing, and I am currently working on line detection. I am using Hough transform on the image below. I'm wondering how I can improve the efficiency of the Hough ...
1
vote
2answers
439 views

hough voting, turning transformation into a vote

I need help understanding how/what does it mean to "turn" a transformation parameters into a vote. I know how to recover the transformation parameters (in my case: 6 DOF), but how this turns into a ...
12
votes
2answers
3k views

Alternatives to Hough transform for detecting a grid-like structure

I have an image which is composed of multiple 'angles' which form a grid shape: After some searching, Hough seemed like a good fit, because it isn't troubled by breaks in lines. However, the ...
4
votes
2answers
3k views

find the gradient direction at a point in a shape

I am trying to implement the generalized Hough transform in matlab. The algorithm requires the gradient direction at each point in the shape. How can I measure $ \phi $ as shown in the figure below? ...
17
votes
3answers
9k views

help understanding hough transform

I'm trying to get a Hough transform to work in MATLAB, but I'm having problems. I have a really bad way of detecting peaks that needs to be fixed, but before that I need to be able to reverse the ...
8
votes
4answers
1k views

How to do De-Houghing of a Hough transform'ed Image?

I'm working with code found at Rosetta Code for creating a Hough transform. I now want to find all the lines in an image. To do so I need the ρ and θ values of each of the peaks in the Hough space. A ...
13
votes
1answer
2k views

Detection of circles (ellipses) in 2D point cloud

Given a set of points (2D) i.e., point cloud (PC), the question is about a robust, accurate and ...