Questions tagged [scale-space]
The scale-space tag has no usage guidance.
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What is the difference between single scale and multi scale?
My question is about the difference between single scale and multi scale in scale space theory. But I think I have to write what I understand about scale space theory and what I guess is the ...
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How are the edges of an image obtained with anisotropic diffusion?
I already know how to implement the method and obtain a correctly diffused image, but in the papers related to the topic there is usually an edge map that's calculated after the diffusion is performed ...
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SURF normalisation and Haar wavelet
I am reading the SURF paper (Speeded-Up Robust Features (SURF)) but can't understand two things. In 3.2 it says:
Furthermore, the filter responses are normalised with respect to their size. This ...
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Losslessness of Laplacian Pyramid
I was just reading up on the Gaussian pyramid and the Laplacian pyramid, used in compression applications of image. The source is here - Carnegie Mellon 16-385 Computer Vision - Spring 2019, Lecture 3 ...
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The Concept of scales in Gabor filter
I've been reading about Gabor filters, and there is a concept of scale. While I understand that Gabor features help in analyzing both the frequency and orientations of an image, what is the idea of ...
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Creating realization of 2D Gaussian field in Fourier space
I want to generate a 2D Gaussian field with dimensions $L\times L$ with $N^2$ cells each of size $l = L/N$. I'm doing this by producing a realization of this field in Fourier space by producing ...
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Basic difference between Multi-scale and Multi-resolution images
While working on Convolutional Neural Network (CNN) I saw many research articles working on the Multi-scale images. In the literature of image processing I saw there is also Multi-resolution analysis ...
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What are the rough steps in obtaining and processing an image from an infrared camera?
I have asked the same question in stackoverflow, but since I am not getting any responses , I am going to ask it again here.
My project is to design an interface between an IR camera (Xenics XTM-640) ...
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How to calculate x and y of any object inside an image when stretched?
Suppose a image has
Height = 200px;
Width = 100px;
A point in that image which has
Y axis = 40px
X axis = 30px
Now if I ...
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Gaussian Pyramid - How is Subsampling Rate Related to Sigma?
I found a gaussian pyramid implementation in a MOPS paper (feature detection). They use sampling rate $s=2$ and $\sigma=1$ - i.e. to generate a new level of the pyramid, the current level is smoothed ...
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Analytical expression for salient Blob detection in scale space
I am working on exact mathematical expression which can be obtained in image processing tasks.(I do not know much about image processing but my work is more mathmatical) In Gaussian scale space, we ...
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Changing Units of Axis
I'm writing a Code for STFT in matlab and I am in the initial stage. Right now I have managed to do the FFT of a small chunk of a time signal. I used zero padding.
The problem I am facing is that ...
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Looking for pratical quantitative comparison metrics for scaled, delayed and warped Signals
[Nota: I have validated the only answer so far, yet more explicit versions are still welcome]
The following question is detailed in 1D, with time as the ordinal variable. Similar questions could apply ...
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Downsampling and Gaussian Filtering in the Context of Scale Space Pyramids
In the context of scale space image pyramids using Gaussian filters I noticed that it's common to downsample the image after blurring with $\sigma = 2*\sigma_{init}$ . My question is: What is the ...
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Use Scale Space Representation to Filter Single Image
Currently I hope to use scale space representation to filter one image. Features in one image can be filtered using an Gaussian smooth filter with one optimal sigma. It means different features in one ...
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LoG filter creating additional maxima in scale space
To create a scale space, I applied a Laplacian of Gaussian filter on the following image:
After the scale space was created, I plotted circles around local maxima in scale space. However, instead of $...
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Equal contribution criteria during image pyramid construction
In their paper on Image Pyramids, Burt and Adelson state the following about pyramid generation.
An additional constraint is called equal contribution. This stipulates that all nodes at a ...
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Is there two Types of Scale Space in SURF algorithm?
I couldn't figure out below paragraph on SURF paper and hope that someone can help me to understand it.
Bay H., Ess A., Tuytelaars T. Van Gool L. - Speed-Up Robust Features
(SURF), page 4, ...
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Correct image rotation/scale/moving change
I'm pretty new to Image Processing and am using MatLab.
I have an problem were I take an image of light passing trough an set of optical fibers (bundled together) and one were I pass laser energy ...
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Computer Vision - Gaussian Pyramid, Scale Space and Pattern Matching
I am planning to implement a pattern matching algorithm using something like correlation as a matching metric.
I know that the template I am going to use will, if present, have different sizes in the ...
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what exactly does scale mean in scale-space theory?
In image processing, scale-space is a technique to represent an image at different scales. But this really confuses me, since I always think that the word scale just means the size of an object, so ...
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Which sigma to use for edge detection
I know that in many edge detection algorithm the first step is choosing a scale to work on.
We actually operate on the chosen scale by applying a gaussian blur on the original image.
I wanted to ...
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2
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SIFT - why s+3 scales per octave?
I have a problem with SIFT that I do not understand. Lowe [1] proposed in his work the s=3 levels of scale are enough for one octave. Afterwards, he mentioned that ...
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Why is it necessary to implement octaves in sift
I've been studying sift very hard for two weeks.
I found much materials about scale space.
It is very hard to understand scale space depthly.
What I've found and confusing things are that
'scale' in ...
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taylor expansion of scale space function
I see the following expression from http://en.wikipedia.org/wiki/Scale-invariant_feature_transform
The quadratic Taylor expansion of the Difference-of-Gaussian scale-space function, with the ...
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466
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Keypoint position and scale in SIFT
If I understood it right, a keypoint is a tuple $$(x,y,\sigma, r),$$ where $x,y$ define the position of the keypoint and $r$ an orientation (given by the most domiant gradiant vector around the ...
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Scalogram (and related nomenclatures) for DWT?
My understanding of the scalogram is that, for a particular row, the scores of the projection of the input signal with the wavelet at a particular displacement is shown. Across rows, the same thing ...
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Sample keypoint found in multi-scale to one scale (scale space with O octaves)
For a multi-scale keypoints detector, local extremas are found between the scales at EACH octave.
The scale-space is implemented as follows:
Each octave is downsampled by half from the first image in ...
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Approximating pixel location in scale space
I'm implementing a scale-space with o octaves and s scale levels in each octave.
Each octave is half the size the previous.
I have keypoints found in each octave, I need to approximate the real ...
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Function for response over image scales
I want to write code in matlab to find a characteristic scale of an image patch.
I have an image patch X, I need to maximize function F(X,sigma) so that sigma is ...
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The Scale Space Theory Understanding
In the scale-space theory the scale-space representation of the signal $f(x), x = (x_1, ..., x_d)$, (in case of image $d = 2$) is given as:
$L(x, y; t) = g(x, y; t) * f(x, y)$ where $g(x, y; t)$ is a ...
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Why is the difference of gaussians scale space scale invariant?
I'll use the Scale-invariant feature transform algorithm as an example here. SIFT creates a scale space based on scaled gaussian filtering of an image, and then computes the difference of gaussians ...
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