# 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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### analyze convolution in spatial domain against multiplication in frequency domain

Lets say I have a image of $NxN$ and a separable filter that I want to apply on it. there are 2 ways to do that: 1. By convolution in spatial domain. 2. By multiplication in frequency domain. I need ...
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### Why is the square of an image not equvalent to taking the autoconvolution of an image in fourier space?

Al right I know that in order to multiply in the normal domain I have to take the convolution in Fourier domain but when I do so in matlab and invert the result then I come up with nothing but a lot ...
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### How comes plotting affine curve as shadows of gray modulo integer resembles its real locus?

Let $f(x,y)$ be polynomial with integer coefficients. Pick integer $n>2$. Let $M$ be $n \times n$ matrix. Set $M_{i,j}=f(i,j) \mod n$. Plot $M$ as bitmap in shadows of gray where larger value is ...
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### How can mathematical models be applied to image analysis

I'm quite interested in how mathematical models can be used in analysing images. For example, I'm aware that mixed effect models can be using in image analysis but I was just wondering if there are ...
I am trying to perform Haar wavelet transformation on the following vector which is defined over $GF(2)$. $[1, 0, 1, 0, 1, 0, 1, 0]$ I am doing it as follows. $[1, 0, 1, 0, 1, 0, 1, 0]$ $\implies ... 0answers 37 views ### deconvolution of exp($x^2$) I would like to know whether we can get the function of type exp($x^2$) by convoluting any functions. That is which function convolution gives exp($x^2$). Thanks in advance 0answers 337 views ### 2D Discrete Fourier Transform on an Image - Example with numbers (rgb) I am trying to write my own function that takes an image, an pixel by pixel it calculates that pixel value that will produce a 2D Fourier Transform image. I have no idea about signal processing, my ... 0answers 84 views ### Algorithm for high contrast Using this algorithm I can increase contrast but applications like Paint.Net can increase contrast significantly. For example it can convert to (by setting contrast to 100 and brightness to 100, ... 0answers 56 views ### Given x,y,w,h can you generate a rainbow box/cuboid with rounded edges? Given$x$,$y$,$w$,$h$where$0 \leq x < w$and$0 \leq y < h$and$(x, y)=(0, 0)$is bottom-left and$(x, y)=(w-1, h-1)$is top-right and they're all integers, can you make a formula that ... 1answer 65 views ### 1D FFT on rotated image column by column I am facing a problem: performing 1D FFT on a rotated column by column on a rotated image, described as following: Original Image: Rotated Image: What I have: original image convolution ... 1answer 35 views ### Singular Value Decomposition for an image understanding I'm trying to get an intuitive understanding of what an SVD decomposition does to an image. From my understanding, for an image$A \in \Bbb R^{m \times n}$, the singular values are the roots of the ... 1answer 82 views ### Convert a pixel displacement to angular rotation? I have camera at which i know the distance to it, its HFOV, and each frame has resolution axb. How would one convert a pixel displacement between the center of frame and the object into a propper ... 1answer 28 views ### The most efficient way to find a minimal value in a 2 dimensional matrix. Suppose we have a matrix A with value of elements ranging from 0 to 255 ( a greyscale image). What is the most efficient algorithm that will return a minimal value found in this matrix? 0answers 42 views ### Perspective view and calculating based on it I've got a project in which i'm asked to use an image captured in perspective view of a lane road (Assume the distance of the camera and the angle relative to the road are known). What I need to do ... 1answer 120 views ### Calculating an Intensity Centroid I am trying to understand the theory behind calculating an Intensity Centroid (image processing), in particular defining moments. As defined by Rosin 1:$m_{pq}=\underset{x,y}{\Sigma}x^py^qI(x,y)$... 0answers 44 views ### Eigenvalue and informations? I have been wondering about this these last couple of days and cannot seem to understand how come this is the case.. I know about the eigevalues and the eigenvector, and that it can be found on for ... 0answers 50 views ### Interpolation of jacobians for point wise defined transformation Here is my question: let's say that I have a transformation function T from the image A to the image B which is pointwise defined. That is, T(x) = J, where J is the jacobian representing the ... 1answer 93 views ### New Horizons at Pluto I recently posted this question on the signal processing site http://dsp.stackexchange.com/questions/23768/new-horizons-at-pluto The only answer was less detailed than I hoped for, so I'm trying here ... 0answers 135 views ### Eigenvalues and Harris Matrix In image processing is possible to detect a corner by looking at the eigenvalues of the Harris matrix. Harris matrix can be here http://docs.opencv.org/doc/tutorials/features2d/trackingmotion/... 1answer 52 views ### Why is my phase correlation not equal to the real correlation? If I understand the correlation theorem correctly, it states:$ f(x,y) \unicode{x2606} \bar g(x,y) = \mathfrak{F}^{-1} \left\{ F^*(u,v) G(u,v) \right\}, $also called a phase correlation. Above$f(x,...
Let $\text{SPD}^n$ and $\text{PD}^n$ be the symmetric semi-positive and positive definite matrices in $\mathbb{R}^{n\times n}$, respectively. I want to find an $X\in \textrm{SPD}^n$ that minimizes \$||...