FPGA Central

Hi!

I'm working on implementing an image co-processor in hardware, and I
wonder if anyone here knows where to look for a hardware
implementation of the median filter algorithm.

I work with 3x3 and 5x5 filter kernels, on 8 bit unsigned (gray)
images. The problem is that I'm always working with four pixels in
parallel (four sequential pixels in the image) and that I always read
out four sequential pixels from the memory.

I found something at google groups that looks like what's follow, but
I don't know how to read out any information from this. Where can I
find the publication mentioned below?


*From: Mr W E Denton (AD) <[email protected]>
For a fast histogram based median filter try:

@ARTICLE{huang79,
author = {Thomas S. Huang and George J. Yang and Gregory Y. Tang},
title = {A Fast Two-Dimensional Median Filtering Algorithm},
year = 1979,
journal = assp,
volume = 27,
pages = {13-18},
abstract = {We present a fast algorithm for two-dimensional median
filtering. It is based on storing and updating the gray
level
histogram of the picture elements in the window. The
algorithm
is much faster than conventional sorting methods. For a
window
size of m x n, the computer time required is o(n).},
number = 1,
month = feb
}
@STRING{assp = "IEEE Trans. on Acoustics, Speech, and Signal
Processing"}

* From: Roger Koenker <[email protected]>
You might look at the following paper:

%AUTHOR = Rousseeuw, Peter J.
%AUTHOR = Bassett, Gilbert W., Jr
%TITLE = The remedian: A robust averaging method for large data
sets
%JOURNAL = Journal of the American Statistical Association
%VOLUME = 85
%PAGES = 97-104
%YEAR = 1990
%KEYWORDS = Recursive estimation


best regards,
Andreas Lundgren

(PS. I will also post this message at comp.lang.vhdl and
sci.image.processing)