# Implementation of parallel 2D median filtering

Discussion in 'VHDL' started by Andreas, Dec 2, 2003.

1. ### AndreasGuest

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) <>
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 <>
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.verilog and sci.image.processing)

Andreas, Dec 2, 2003

2. ### Tuukka ToivonenGuest

In article <>, Andreas wrote:
> @STRING{assp = "IEEE Trans. on Acoustics, Speech, and Signal
> Processing"}

Many IEEE publications are available at
http://ieeexplore.ieee.org/Xplore/DynWel.jsp
But you must have account there which is expensive
(some universities etc. might have account for all
personnel including students).

Otherwise, go to university library, either they have
it or can order (may cost again).

Tuukka Toivonen, Dec 2, 2003