# Tagged Questions

This tag is for the mathematics involved in the field of image processing. Many such questions are also appropriate for Signal Processing Stack Exchange.

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### Alignment of one 3D Coordinate system to another 3D Coordinate system

I'm working on a project depicted by this picture(taken from internet) where there are different coordinate system involved which corresponds to camera coordinate system and local 3D coordinate system ...
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### Estimate original matrix from matrix multiplication result

Let $A$ be $m \times n$ real matrix. Let $B$ be $n \times k$ real matrix. Let $C= A \times B$ ($m \times k$ matrix). Now, the question is: given $C$ and $A$, give an estimate for $B$. Possible ...
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### recursive least squares for nearly singular matrices

I have an image reconstruction problem which I want to solve as a linear system $Ax=y$. A matrix is big, but for the beginning I can shrink the imaging region to $nPix$ = 2000 pixels. number of ...
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### Thinning vs. medial axis transform

Both thinning and medial axis transform of a binary image produce a simplified version of the image, reducing the connected components to single-pixel wide subsets, also called skeletons. The one ...
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### Minimizing $E(q)=\lambda(q-p)^T(q-p)+q^TLq$

Let $E(q)=\lambda(q-p)^T(q-p)+q^TLq$, where $\lambda$ is a scalar, q and p are n by 1 column vectors, L is an n by n positive definite matrix (Actually Laplacian matrix, in image processing field)....
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### When is a mapping the proximity operator of some convex function?

Sorry for cross-posting from MO. It's been a few days and the question hasn't received any attention there. So, is there a characterization of mappings $p : \mathbb R^n \rightarrow \mathbb R^n$ which ...
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### What are kernel space, functions and data?

I'm reading Kernelized Locality-Sensitive Hashing, which is obviously based on the concept of kernel applied to space, functions and data. It seems particular relevant in image processing domain, but ...
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### Produce a 4:2:2 sub sampled Y matrix, Cr matrix, Cb matrix for an image

I have write the matlab code below for to extract Y, Cb, Cr information from the picture: ...
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### Contour and perimeter recognition in binary image

I need to detect contour (object) and find the perimeter of a detected object. For example, I have the following image: http://i.stack.imgur.com/40TTX.png All images are binary, so they consist of ...
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### Relation between focus and camera intrinsic parameters

Does a focus tuning affect the camera intrinsic parameters? More precisely, if the focus of a camera is changed, does the camera intrinsic parameters matrix remain unchanged? Apparently, since this ...
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### Does the ring in this Fast Fourier Transform image of a hexagonally close packed structure have significance?

I have a picture of a hexagonally close-packed lattice and I took the FFT of the image using ImageJ. Below are the results. I expected the FFT to also be a lattice with reciprocal lattice spacing, I ...
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### I downloaded the SPARCO package (MATLAB)and when setting it up a problem has occured

I downloaded SPARCO1.2 (MATLAB) from http://www.cs.ubc.ca/labs/scl/sparco/ and when I use the command 'sparcoSetup' it says everything is successful. But then when I use the command 'checkProblems' ...
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### Number of operations in convolution of an image with a sequence of kernel

In the vein as this question, I'm trying to see how many operations convolution takes (in the context of image processing), as illustrated by the following GIF: I'm interested in the naive ...
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### Distance between a map and a point using bicubic interpolation

I have an image (i.e., a two dimensional regular grid) with pixel values that represent elevations. To interpolate points of the surface described by the grid, I use bicubic interpolation. The image, ...
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### Transformation between camera velocity and projection of a tube's cut

I have a vision sensor / flying camera inside a circular tube as shown below: The camera is using the pinhole model and I am using edge detection to detect the "black" hole that is forming due to ...
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### Calculate if image dimensions are too horizontal or vertical

I'm working on a PHP script that adds images to articles automatically. A common problem I've encountered is that the image dimensions can be too wide or too tall. In terms of aspect ratio of wide ...
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### Maximum absolute deviation

Let $I$, $J$ be two gray scale images. How will I be able to interpret the maximum absolute deviation between the histograms of these images?
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### Pyramidal Histogram Of Oriented Gradients - Trilinear interpolation

Hello im struggling with an implementation of this article: https://goo.gl/8mpIuq I performed bilinear interpolation over the histogram bins and the results are better with this interpolation, ...
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### Method for finding basis of an image

I know the traditional method for finding an image of a matrix is finding the pivot columns of the rref of the matrix and then the corresponding columns are the basis of the image, but I'm wondering ...