# Stefan Karlsson

### Halmstad University

Post doc in Image analysis/computer vision/biometrics

Professional Interests: signal processing, biometrics, image analysis, computer vision

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**2** Questions

**12** Answers

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RANK**229** of 17,210

REPUTATION**5,708**

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CONTRIBUTIONS**8** Files

DOWNLOADS **22**

ALL TIME DOWNLOADS**55085**

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**Content Feed**

Submitted

Tutorial and Toolbox on real-time optical flow

Code with visualization and excercises. Camera supported

12 months ago | 6 downloads |

What frustrates you about MATLAB?

I miss the ability to define your own workspace. When doing event driven programming in Matlab, there are 3 ways to share your o...

5 years ago | 0

Submitted

FancyFlowPlayer

Video Player with visualization and interactive reading.

6 years ago | 1 download |

Submitted

Interactive Incompressible Fluids (Karlsson version)

An interactive demo of Navier-Stokes equations for incompressible fluids.

6 years ago | 2 downloads |

Global workspace usage for efficiency?

Walters good points above are not an answer to my question. Let me try to give my point of view on this, and then anyone can fee...

6 years ago | 0

Question

Global workspace usage for efficiency?

*Are there cases when using global variables is the most efficient implementation?* I hate using the global workspace, but I ...

6 years ago | 2 answers | 0

### 2

answersCan I use PCA effectively on a greyscale image?

... I guess one can also give another piece of advice to anyone who stumbles onto this looking for info on PCA. Read the posts b...

6 years ago | 0

Can I use PCA effectively on a greyscale image?

I think the answer by Walter, while technically correct, confounds a VERY simple topic. Being technically correct here amounts t...

6 years ago | 0

Scale a mask in an image

use imresize. If you use it with interpolation 'nearest', you have your functionality in a single line. If you use another inter...

6 years ago | 1

Submitted

Real time optical flow, and video processing

Real time optical flow, and video processing, with support for camera input in Matlab.

6 years ago | 4 downloads |

timer and Interruptible=Off button callback priority/preemption?

Sometimes I get into the problem that I am in a function that is not interuptible. An ugly work-around that seems to work (o...

6 years ago | 0

Save data X over Y

Poorly asked question. Do you get 2 new X and Y matrices by regular intervals, or is time-dependency something represented by t...

6 years ago | 0

Which way is correct of defining function...I am getting two differnt surfaces if I specify same equation differently...?

There are 2 interpretations of your shared code (i.e. two ways i see that you would be able to run it without error). 1. you ...

6 years ago | 0

| accepted

GUI figure focus

Seems this is still an issue, here is my solution quick fix: %takes any active uiobject as input, and returns keyboard fo...

7 years ago | 0

Submitted

Visual Studio Toolbar for mex interface with video tutorial

Seamless interface, VS 2010 and 2012 and Matlab for MEX. Video linked to step you through.

7 years ago | 3 downloads |

What frustrates you about MATLAB?

topping the wish-list: 1. A "beep off" that actually works, stops Matlab completely from making the OS beep sound. 2. A sh...

7 years ago | 0

Solved

Swap the first and last columns

Flip the outermost columns of matrix A, so that the first column becomes the last and the last column becomes the first. All oth...

7 years ago

Submitted

Optical Flow with Matlabs Computer vision toolbox

optical flow on camera, synthetic video and video files

7 years ago | 3 downloads |

Solved

Make a checkerboard matrix

Given an integer n, make an n-by-n matrix made up of alternating ones and zeros as shown below. The a(1,1) should be 1. Example...

8 years ago

Solved

Find all elements less than 0 or greater than 10 and replace them with NaN

Given an input vector x, find all elements of x less than 0 or greater than 10 and replace them with NaN. Example: Input ...

8 years ago

Solved

Triangle Numbers

Triangle numbers are the sums of successive integers. So 6 is a triangle number because 6 = 1 + 2 + 3 which can be displa...

8 years ago

Solved

Determine if input is odd

Given the input n, return true if n is odd or false if n is even.

8 years ago

Solved

Column Removal

Remove the nth column from input matrix A and return the resulting matrix in output B. So if A = [1 2 3; 4 5 6]; and ...

8 years ago

Solved

Select every other element of a vector

Write a function which returns every other element of the vector passed in. That is, it returns the all odd-numbered elements, s...

8 years ago

Solved

Find the sum of all the numbers of the input vector

Find the sum of all the numbers of the input vector x. Examples: Input x = [1 2 3 5] Output y is 11 Input x ...

8 years ago

Solved

Make the vector [1 2 3 4 5 6 7 8 9 10]

In MATLAB, you create a vector by enclosing the elements in square brackets like so: x = [1 2 3 4] Commas are optional, s...

8 years ago

Solved

Times 2 - START HERE

Try out this test problem first. Given the variable x as your input, multiply it by two and put the result in y. Examples:...

8 years ago

Submitted

VideoResize

A MUCH faster version of "imresize", specifically for videoprocessing

8 years ago | 1 download |