Vol.29 Suppl. No. 2 ( 2 0 0 9 10
B 1
*
, Rormy Mardiyanto(
Computer input with human eves only using blink detection based on
Gabor filter
Kohei Arai and Ronny Mardiyanto
ABSTRACT
A method for computer input with human eyes only using blink detection based on Gabor filter is proposed. In
order to detect eye blinking, we utilize top and bottom of eye arcs. Distance between top and bottom of these arcs is
equal with percentage of open-closed eye. If this distance is maximum, it sign that eye is open 100%. Otherwise, if
this distance is close to zero, it means that eye is open 0% (or eye closed).
Keywords: Gabor filter, Blink detection, Line of sight vector estimation
1.Introduction
Gabor filters are directly related to Gabor wavelets, since
they can be designed for number of dilations and rotations.
However in general, expansion is not applied for Gabor
wavelets, since this requires computation of biorthogonal
wavelets, which may be very time-consuming. Therefore
usually, a filter bank consisting of Gabor filters with various
scales and rotations is created. The filters are convolved with
the signal, resulting in a so-called Gabor space. The Gabor
space is very useful in image processing applications such as
iris recognition and fingerprint recognition. Relations between
activations for a specific spatial location are veiy distinctive
between objects in an image. Furthermore, important
activations can be extracted from the Gabor space in order to
create a sparse object representation.
In order to detect eye blinking, we utilize top and bottom of
eye arcs. Distance between top and bottom of these arcs is
equal with percentage of open-closed eye. I f this distance is
maximum, it sign that eye is open 100%. Otherwise, if this
distance is close to zero, it means that eye is open 0% (or eye
closed).
2. Proposed method
Two-dimensional Gabor functions were proposed by
Daugman
1
) to model the spatial summation properties (of the
receptive fields) of simple cells in the visual cortex. They are
widely used in image processing, computer vision,
neuroscience and psychophysics. The parametrisaton used in
Eq.(l )follow s references
2
wher e furthe rdetail scanbefound .
This block implements one or multiple convolutions of an
input image with a two-dimensional Gabor function:
, e, (y)=
+7
2
2A
3 (
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= sain© j;C0ft©
To visualize a Gabor function select the option "Gabor
function" under "Output image". The Gabor function for the
specified values of the parameters "wavelength", "orientation",
"phase offset", "aspect ratio", and "bandwidth" will be
calculated and displayed as an intensity map image in the
output window. (Light and dark gray colors correspond to
positive and negative function values, respectively.) The
image in the output widow has the same size as the input
image: select. If lists of values are specified under
"orientation(s)" and "phase offset(s)", only the first values in
these lists will be used.
The half-response spatial frequency bandwidth b (in
octaves) of a Gabor filter is related to the ratio a / X, where a
and X are the standard deviation of the Gmissian factor of the
Gabor function and the preferred wavelength, respectively, as
follows:
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