Integrated Science Academy
Color Change: Illumination and
Observers
Che
Shen
Color Science Ph.D.
candidate
Abstract:
While color change is
often associated with physical or chemical alterations in an object, this
thesis focuses on perceptual color changes due to factors like color
inconstancy under different lighting conditions, observer metamerism due
to varying color matching functions, and individual differences in hue
perception despite identical tristimulus values.
Based on the complexities of color change phenomenon, a psychophysical
experiment was conducted to establish the threshold of color inconstancy,
where observers were tasked with categorizing colors under varying
lighting. A major advancement in this thesis is the development of the
Weighted Geometric Mean (WGM) model, an advanced chromatic adaptation
model grounded in the principle that sensory adaptation follows a
geometric mean approach. This model marks a significant progression in
understanding and predicting color adaptation under various lighting
conditions.
A key finding from the psychophysical experiments is the impracticality
of using unique hues as a reference for assessing observer metamerism.
This insight led to the development of the innovative observer metamerism
index, which utilizes individual color matching functions (CMFs) and a
simulation approach to quantify metamerism more effectively.
Additionally, a cross-media color-matching experiment, merging physical
pigments with self-emitted light display, is presented to assess
individual color matching functions. This experiment challenges existing
standards and demonstrates the effectiveness of personalized CMFs in
color reproduction, enhancing the accuracy of color
perception.
Another significant contribution of this thesis is the development of an
algorithm for hue appearance equalization, tailored to the unique hue
perception of individual observers. The effectiveness of this algorithm
is validated through a user study indicating the influence of memory
color and highlight the need for further exploration into the real-world
application of hue adjustment
techniques.
Intended Audience:
All are welcome.
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