All Questions
16 questions
35
votes
5
answers
6k
views
What factors should I consider in choosing an edge detection algorithm?
I've learned about a number of edge detection algorithms, including algorithms like Sobel, Laplacian, and Canny methods. It seems to me the most popular edge detector is a Canny edge detector, but is ...
- 1,610
19
votes
4
answers
14k
views
What Are the Limitations of a Canny Edge Detector?
Broadly a majority of the literature on edge detection algorithms and applications that uses edge detection, references Canny's edge detector. So much so that it looks like almost "the solution" to ...
- 5,597
5
votes
2
answers
10k
views
Edge Detection on a Color Image
I understand the process of using a Sobel kernel for edge detection in greyscale images. The input is a greyscale image, and the output is a greyscale image. I'm having trouble, however, figuring out ...
- 153
5
votes
1
answer
1k
views
What's Logic Behind the Construction of Sobel's Filter in Image Processing?
I am basically very new to this image processing field. I am presently working on edge detection on colour images. While learning the basics of edges and edge detection in images, I encountered image ...
- 213
4
votes
1
answer
326
views
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 ...
- 43
11
votes
2
answers
443
views
Explanation on Haarlets
Would someone be able to give me some info or a link etc ... regarding haarlets aka Haar wavelet-like features. I'm reading several papers for my master dissertation and several of these papers ...
- 392
9
votes
1
answer
12k
views
How can I detect elements of GUI using opencv?
Given a screenshot of an application, is there any way of finding GUI elements of that application using only opencv? (something like in the image)
I tried to play with blending the image and other ...
- 185
5
votes
2
answers
2k
views
What's the best technique to determine if the contents of two images are the same?
I need to run comparisons on the output of hundreds of frames of simple 3D-rendered characters. Perceptually, many of the frames are exact duplicates. Based on this, I assumed something like a ...
user15190
5
votes
3
answers
646
views
Are 2nd Order Edge Detectors More Susceptible to Noise?
I am reading about edge detection and I read that 2nd order detectors are more susceptible to noise. Is there a mathematical proof to this ?
- 219
5
votes
1
answer
630
views
Image Edge Preserving Smoothing
I'm searching for a method that can smooth a 3D volume whilst preserving the edges in my volume.
I researched anisotropic diffusion filtering and bilateral filtering, but I'm having trouble to ...
- 121
4
votes
1
answer
6k
views
Sobel Vs Gaussian Derivative
What would be the most significant difference when using either a sobel filter or a gaussian-derivative filter, apart from the obvious difference of the size of the 2 filters?
- 41
4
votes
1
answer
178
views
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....
- 41
3
votes
1
answer
303
views
What is a segmentation mask in the paper "Fast Edge Detection Using Structured Forests"
I've read the paper about edge detection, in this paper they treat edge detection as a learning problem which takes an image patch as input and output a label, a binary edge map or a segmentation mask,...
- 31
2
votes
1
answer
599
views
Designing an efficient curve-matching algorithm
I'm currently designing a curve-matching algorithm and as I already explored many ideas I'm requesting your help. So, if you got some advices about how to handle this problem, feel free to answer!
...
- 378
1
vote
1
answer
5k
views
How to detach overlapping contours but not to remove small ones. Alternative to erosion-dilation cycle
Background:
I'm trying to detect trees on a sequence of aerial images by calculating a stereo disparity for consequent pairs of images. This is how disparity looks like. White spots are trees:
Next, ...
- 133
1
vote
2
answers
3k
views
Why are edges in spatial images represented as edges in their Fourier transform image?
Here is a well-known image and its Fourier Transform (magnitude).
If I understand correctly the theory behind the FFT, each pixel in the FFT image represents a certain 2D sine wave with frequency ...
- 163