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
55
votes
2 answers

Mathematical explanation behind a picture posted (lifted from facebook)

In this image given below, there is an actor's (famous south Indian actor Rajinikanth) image which can be seen only if you shake your head ! I had lifted this from Facebook. I am just curious to know if there is any mathematical explanation for it.…
Rajesh D
  • 4,247
4
votes
1 answer

Reconstruct density function from weighted sums with set of weighting functions

I have encountered the following problem regarding the reconstruction of a particle density function $f$. It is possible to acquire "measurements" of the particle density function $f : [0,1]^2 \rightarrow \mathbb{R}^{>0} $. The discrete measurements…
Mantabit
  • 203
4
votes
2 answers

About Sum of Squared differences

I found a paragraph in the book about $SSD$, can't get one thing: Most commonly, the distance measure is the sum of squared differences. For two images $f(x, y)$ and $g (x, y)$ it is defined as $$ SSD(d_1,d_2) = \sum_{i=-n_1}^{n_1}…
user1448906
3
votes
1 answer

May I know how to solve this Huffman coding-related question?

Question 1: An image is coded with 3 bits per pixel and the probabilities associated with each of the grey levels are P = [0.2 0.15 0.13 0.13 0.12 0.10 0.09 0.08]. (i) Using Huffman coding, derive the variable length codes for …
josephineteo23
  • 33
3
votes
1 answer

Scale invariant Image Moments - not scale variant?

I came across a problem working with image moments [1]. It is stated that $\eta_{ij} = \frac{\mu_{ji}}{\mu_{00}^{k}}$ where $k = 1 + \frac{i+j}{2}$ is scale invariant. However, if I try to reproduce this, it does not appear scale invariant at…
Makx
  • 133
  • 3
3
votes
0 answers

Homography matrix form for decomposition

I am trying to decompose a homography matrix. I read that there are a few methods to do that (e.g. Faugeras, Zhang). But I wasn't able to produce a useful output yet. I am not sure which form my homography matrix needs for decomposition. A few…
ebber
  • 143
2
votes
1 answer

Poisson equation with dirichlet condition

I'm not sure whether this is a mathematics or stack overflow question, but I'll try here as my doubt are because of my lack of maths knowledge. I'm trying to implement an image editing paper that relies on poisson equation with dirichlet condition…
cifz
  • 141
2
votes
1 answer

How to determine if a pixel is inside a contour?

I have following picture which I extract the contour from. The contour looks like following I am wondering, for any pixel in the image, how do I determine if it is inside the contour or not? Say "inside" here means any pixel in the body. If…
Nick X Tsui
  • 456
2
votes
0 answers

Multiphase levelset Chan Vese algorithm

I am implementing the multiphase level Chan Vese algorithm. I am using IPOL document as reference (http://www.ipol.im/pub/art/2012/g-cv/article.pdf) Everything is clear for me, except the stopping criteria: In one level set, the method is…
matlab user
  • 21
2
votes
1 answer

best way to find missing corner on photo of rubiks cube

I've got the following photo of a rubiks cube and edited it so far that I've found out the coordinates of the outer 6 corners: My problem is: How do I find the coordinate of the last corner, which is located in the front of the image? Assume, that…
Applecow
  • 123
2
votes
1 answer

Derive the Separability of 2D Gaussian

I am trying to figure out how to derive the 2D Gaussian as product of 1D Gaussian. I need to learn how the 2pi get the square root in the denomination in the 2D Gaussian.
Pete
  • 215
2
votes
1 answer

Transformation of straight grid lines to a curved grid

I came across a couple of equations to transform straight grid lines to a curved grid. The equations: $$ x=X(x',y')=\sum_{i=0}^{d}\sum_{j=0}^{d-i} u_{i,j}b_{j}(y')b_{i}(x')$$ $$y=Y(x',y')=\sum_{i=0}^{d}\sum_{j=0}^{d-i}…
Ijjz
  • 21
2
votes
1 answer

Can gaussian low pass filter remove ringing effect from the image?

An image is convolved with an ideal low pass filter. The resultant image is convolved with a Gaussian low pass filter to obtain a final image. Will you observe ringing effect in the final image. WPlease give reason.
tarun14110
  • 95
1
vote
0 answers

Potts model for image analysis

I'm trying to get a hold of the Potts model for image analysis, and this is what is posted on Wikipedia, http://en.wikipedia.org/wiki/Potts_model#The_Potts_model_in_signal_and_image_processing $$ P_\gamma(u) = \gamma \| \nabla u \|_0 + \| u-f\|_p^p…
Kirbies
  • 113
  • 3
1
vote
1 answer

Proportional Image Resizing

This is quite a simple one I guess (but my mind is dead currently and is getting cluttered by other numbers). I have an square image that is currently 256 width x 256 height. I am variably resizing this image to a bigger size proportionally, so lets…
Jack
  • 13
  • 3
1
2 3 4 5