Mathematics Stack Exchange
Mathematics Stack Exchange

Questions tagged [image-processing]

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

This tag is for mathematical questions about the field of image processing. Note: programming issues related to image processing belong on other Stack Exchange sites: Stack Overflow, Signal Processing or Computer Science.

649 questions
1
vote
1 answer

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 angular movement. The way i would do it HFOV/a *…
sds
  • 115
1
vote
1 answer

discretization of $div(\psi(x, y)\nabla(u(x, y)))$ for image processing

I am trying to derive numerical scheme for optical flow In Euler-Lagrange equations i obtain following term $div(\psi(x, y)\nabla(u(x, y)))$ where $\psi, u : R^2 \rightarrow R$, $div(u)$ denotes divergence of $u$ I want to obtain system of linear…
Daiver
  • 277
1
vote
1 answer

Given an intensity histogram,we apply an histogram equalization.Calculate the new intensity of the pixels in the original histogram had a150 intensity

It's a question from an exam that I can't understand its result. Given the following intensity histogram of an image: After an histogram equalization applied for this histogram, we've got the following intensity histogram: The question: What is…
Billie
  • 3,449
1
vote
1 answer

Move coordinate system of a 3x3 homography matrix

I have a $3 \times 3$ homography matrix $H$. It was computed the way so that I can multiply a point of my image ($1000 \times 1000$px with coordinates $0/0$ to $1000/1000$) e.g. $1/1$ and get the new position of that point e.g. $2/2$. But I would…
ebber
  • 143
0
votes
1 answer

Hysteresis Image Thresholding

In Image Processing, is it possible to automatically determine the upper and lower levels for a Hysteresis thresholding stage?. I have been looking for a while for a paper mentioning any technique for implementing this but I have not found it. Does…
karl71
  • 133
0
votes
1 answer

Fourier transform in image processing

I want to know what a Fourier transform do to a image, does magnitude of this transform represent the energy of radiations captured by image, or is there any other way to find out the energy of radiation captured by image, using image processing?
Abhinav Gupta
  • 315
0
votes
3 answers

Calculating the next value of sin(x) from previous sin.

(Please bare with me as I try to explain my problem to the best of my abilities) I have a computer program that draws a sine. Each y value of the sine is stored against the x value in an array like so: float sine[x] = y; To find the value of my…
ReX357
  • 69
0
votes
0 answers

What is the Linear Shading Correction Algorithm accurately?

I want to right a code in C# without using pre-written libraries for removing shadows on the edges of the image and there is a algorithm for this(Linear Shading Algorithm) but I can not understand some part of the algorithm. According to…
stck_n
  • 101
0
votes
1 answer

Getting width and height values ​that best fit a certain amount of pixels in an image

If I have n number of pixels, what's the best way to get the factor of n that most resembles a square shape when using it as a dimension of an image? Using n == 512 as an example, its factors are: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512 The values…
Luna
  • 11
0
votes
0 answers

Difficulty understanding method to generate hadamard patterns

I am currently working on a project that requires me to generate Hadamard patterns. I came across this in a paper I was told to refer to. I am not sure what the delta function is meant to do and what it is meant to operate on. I am also not sure…
user846333
0
votes
1 answer

How to estimate the grid size of a rescaled pixel art?

A pixel art image originally has a consistent resolution with its grid size. However, in our case, this image may be upscaled using nearest neighbor upscaling to an arbitrary size (like 16x16 to 200x200), eg, a grid may contain 10 pixels. Our goal…
SF.H
  • 1
0
votes
1 answer

How many different hues, saturations and values are possible when converting RGB to HSV?

If we specify a colour in the RGB space, there are $2^{24}$ different colours, as R, G and B are 8 bit numbers. When a colour is converted to the HSV colour space (find the conversion formulas here for example), how many different values are…
steffen
  • 123
0
votes
0 answers

calculate HD resolutions for an image

I have an image with height=75pixels and width=75pixels (75x75). I want to calculate what the resolution for this image would be in different resolutions [480p (640x480), 720p (1280x720), and 1080p (1920x1080)] while still keeping the image's…
Martin
  • 111
0
votes
0 answers

How to perform 2d deconvolution for the Gaussian kernel and the gradient operator?

I have an images $u \in R^{M \times N}$, a Gaussian kernel $G$ and the gradient operator $\nabla u_{i,j}=[\nabla_{x} u_{i,j},\nabla_{y} u_{i,j}] \in (R^{2})^{M \times N}$ and I need to perform 2d deconvlotion as $(G \otimes \nabla u)_{i,j}$. Since…
eli
  • 23
  • 4
0
votes
0 answers

How to create path following contour

I have an image (black & white) that represents a letter in the alphabet, and I want to create a path (x y coordinates) to represent the letter. For example, I have this image of the letter C (image of the letter C) I want to trace the white pixels,…
Khaled
  • 101
1 2
3
4 5