1. Remote color control of a LED-lamp for human
judgment about color
Charitha Weeraasuriya; Prof. Saulius Juodkazis
Faculty of Science, Engineering and Technology, Swinburne University of Technology
INTRODUCTION
METHODS
CONCLUSIONS
DISCUSSIONRESULTS
REFERENCES
ABSTRACT
CONTACT
Figure 2. CIE 1931 Chromaticity diagram.
Charitha Weerasuriya
Email: weerasuriya@gmail.com
Phone: 0411 275 713
Color plays an important part in
human activities. It influences in many
ways when it comes to the human
decision making process. Therefore, it is
significantly important to investigate
human judgment about colors when
objects are illuminated with different
colors.
In this report, we discuss the controlling
of a red (R), green (G), Blue (B) and
Amber (A) colored lamp (LUME-20R LED
lamp from Ledigma Ltd.) with
MagnetoEncephaloGraphy (MEG) brain
scanner. This project developed a
software to generate all the colors in the
visual spectrum, predefined white light
combinations and saturation of an
illuminated objects by using RGBA colors.
The lamp is required to control from
outside of the shielded room because,
MEG scanner and LED lamp are located
inside of electromagnetically shielded
room. Hence, USB is used as a
communication mode in this project.
To check the feasibility of using LED lamp
with MEG brain scanner, several tests
have been conducted and those finding
are given in this report. From the results
of our tests, we have concluded that, it is
feasible to use LUME-20R LED lamp, color
control software and MEG scanner
together for human and color related
research.
LUME-20R lamp is designed to be controlled via Bluetooth
communication. However, in this application it is impossible to
communicate with lamp via wireless, because lamp is installed
inside the electromagnetically shielded room. Therefore, USB
communication method has been selected as shown in Figure 3.
The person has to site on the Magnetoencephalography (MEG)
scanner to measure brain magnetic field as below Figure 4.
The software has been designed to control the lamp from
outside of the shield chamber. The software has features to
control red, green, blue and amber colors individuality. This
gives an opportunity to illuminate objects with diversified color
combinations. Moreover, the developed software is capable to
set predefined CCT setting, which is 1500K (candle light), 3500K
(Halogen) and 6500K (daylight). That enables to set the lighting
system to different modes. In addition to that, software is
capable to control saturation of the illuminated objects. This is
one of the strong features available in our system, which gives
opportunity to increase the color fidelity of the objects. This
feature has many commercial implications, such as for use in
display lights, art galleries etc. Figure 5 gives the screen shot of
RGBA lamp controller panel. The software architecture is given
in block diagram format in figure 6.
The MEG scanner is very sensitive to magnetic field. Therefore,
to verify the impact of lamp and software on MEG scanner,
initial test was conducted. The test combinations and results are
given below Table 1 & Figure 7.
At this initial stage, the main objective has been to verify
the capability of using this Lamp and controller software
together with MEG scanner. Therefore, the experiments
were conducted as specified in the Table 3-1. Based on
that results, the MEG scanner research team came to a
conclusion, that there is a possibility to utilized the lamp
and the controller for brain & color related research.
Furthermore, to investigate human judgment about color
requires expert knowledge to design test procedures and
methods. There are many challenges to solve, such as how
to differentiate other brain activities from color related
brain activities and how human stress is involved in the
process.
This project was conducted by utilizing the LUME-20R RAIL
LUMINAIRE lamp which is a product of LEDIGMA. The
color rendering theories and The CIE 1931 color space
chromaticity diagram coordination are being used to
calculate red (R), green (G), blue (B) and amber (A) color
combinations for given correlated color temperature and
color saturation. The CIE 1931 Chromaticity diagram is
shown in Figure 2.
In conclusion, this project successfully developed a
controller for the LUME-20R lamp via USB from outside
the electromagnetic shielded room. Based on test data, it
shows that LUME-20R lamp and MEG scanner
combination can be used in many brain & color related
research.
The color controller software is capable of controlling
color saturation of an illuminated object as per user
requirements. Furthermore, the software gives a
comprehensive range of color combinations, such as all
the colors in the spectrum, white light options and color
hue, saturation and brightness.
Finally, this project has proven that, the LUME-20R lamp
and USB color controller software, are feasible to apply
MEG scanner related research and many others.
The objective of this project is to develop an LED
bulb controller to illuminate objects with different color
combinations and a user interactive device to be used in
magnetically shielded room. This controller is used in the
research of investigating human judgment about color
when illuminating an object with different color
combination to identify parts of the brain which is
involved in decision making about color. The block
diagram on the system is given below Figure 1.
Zukauskas, A. et al., 2012. Color rendition engine. Optics
Express, Feb, 20(5), pp. 5356-5367.
Figure 1. Block Diagram.
Test
Color of
the
lamp
Human
inside MEG
room
1 - No
2 - Yes
3 Candle Yes
4 Candle No
5 Amber No
6 Red No
7 Green No
8 Blue No
ATxmega16
A4-AU
TXD0
Pin 32RXD0
Pin 33
Vcc
GND
TX
RX
USB
UART to USB
USB
cableGND
Figure 3. LUME-20R wire connection
for USB communication.
Figure 5. : RGBA LED Lamp
controller software
Table 1. Test combinations.
Figure 6.: Software architecture
in block diagram
Figure 4.: MEG measurement
Figure 7.: MEG measurements data with person in FFT & logarithmic format