Steve on Image Processing

December 9th, 2008

Online resources: psychophysics, colour engineering

Here are two sources of useful MATLAB functions that readers might be interested in.

First, an acquaintance at Apple Computer recently told me about the Psychtoolbox. He thought that any researcher using MATLAB to do experiments involving human visual perception might find it useful. I surfed around the web site and was impressed with the content and activity evident there.

Here's a brief description from the home page: "Psychophysics Toolbox Version 3 (PTB-3) is a free set of Matlab functions for vision research. It makes it easy to synthesize and show accurately controlled visual stimuli and interact with the observer."

Second, I saw a link today for the "Colour Engineering Toolbox," a set of MATLAB functions written by Phil Green and associated with the book Colour Engineering, which was co-edited by Green and Prof. Lindsay MacDonald. Both are with the Colour Imaging Group in the London College of Communication. Dr. Green's functions include colour space conversions for a few device-independent spaces, white-point utility functions, mathematical utilities useful for colour computations, colour difference and CIECAM02 computations, and a few psychophysics functions related to experiment design and associated statistics.

There's lots of good MATLAB stuff out there, so don't think you have to implement everything yourself. In addition to Internet search engines, be sure to check out the MATLAB Central File Exchange.

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Steve Eddins manages the Image & Geospatial development team at The MathWorks and coauthored Digital Image Processing Using MATLAB. He writes here about image processing concepts, algorithm implementations, and MATLAB.

  • Sana: hi steve, could you explain to me how i would be able to use the dir function, to do a loop through a directory...
  • Nishtha: Sir, I have preprocessed the image in following steps: [1] adaptive histogram equalization [2] thresholding...
  • Kristof: I also strongly support the idea. I have just recently bumped into the problem that im2single was not...
  • Steve: David—I’ m glad you found it useful!
  • David Lalejini: I found your example very useful for finding connected nodes in a large set of input pairs. I start...
  • tommy: Dear Steve, I have a question,please if you are kind to help me regarding the accumulator array dimensions of...
  • Steve: Abc—I don’t know how to distinguish the faces. You might try posting your question in the MATLAB...
  • Manju: well if we have a few ovals within each other like in a cell how do we measure the distance from the center...
  • Steve: Manju—What do you mean? How is each region defined?
  • Manju: if we have 2-3 regions within each other how do we measure the regions of each one?

These postings are the author's and don't necessarily represent the opinions of The MathWorks.