Code :

This section provides some pieces of C code I wrote.
These are usually very simple, but they should work.
If you encounter any problem, don't hesitate to tell me : florent@uchicago.edu
Some of these files are simple c code functions, some other are ".tgz" packages of Xcode, or ProjectBuilder, I use on Mac OSX.

You will find here a cross correlation function, a 2D convolution, a 2D difference of gaussian, some Zernike polynomials computation, a 2D bi-cubic interpolation, and a program drawing simple geometric shapes as bitmaps.

The Convolution program uses the convolution theorem, many thanks to Paul Bourke, which kindly allowed me to use his very efficient 2D FFT source code. By the way, you will find plenty of very interesting stuff on his web page. I am using this same FFT transform for other programs which will be soon available.

The cross correlation (1) program is strongly based on Paul Bourke's one. I mainly added the piece of code to read and write input/output data. I extensively used this code during my PhD studies.

I am using the Difference Of Gaussian (1) (DOG) program to model spatially antagonistic center surround receptive fields in the study of human color perception. This code also convolves an input image by the DOG filter.

The Zernike polynomials (1)(2) are very useful in modelling optics of the human eye.

The 2D bi-cubic interpolation (1)(2) is based on Based on "Cubic Convolution Interpolation for Digital Image Processing", Robert G. Keys, IEEE Trans. on Acoustics, Speech, and Signal Processing, Vol. 29, No. 6, Dec. 1981, pp. 1153-1160. This is a translation of Matlabs' interp2() function. I programmed several interpolation functions, I just put here the one which gives the closests results to interp2.m.

I wrote the CreateStimulus package to create psychophysics stimulus as bitmaps, in order to be able to perform several processings on these maps (e.g. filtering). I may be the only person willing to use this code, but I put it here anyway, if you find any application to use this code, let me know. This program allows drawing squares, rectangles, circles, lines, grids of different size or chromaticity.

Go back to home page !

N.B : I wrote these programs as part as the Retinal image software, dealing with the study of human color perception and the chromatic aberrations of the human eye.
Some of these links will only provide the C code functions, you'll have to make the corresponding main function, or use it directly as part as the Ret-Img package.

/*************************************************************************************
These programs are free software; you can redistribute them and/or modify
them under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
*************************************************************************************/

/***************************************************************************
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Last modification : july 9th 2004
Florent Autrusseau
email : florent@uchicago.edu
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***************************************************************************/