Student Awards

Wednesday 2nd December 2020 14.00-15.30

ONLINE – Please sign up at eventbrite link below.

Every year the Colour Group (GB) supports a number of outstanding student and Early Career postgraduate members with financial support in the form of  awards. These awards allow early career researchers to attend international conferences in order to present their work, and also recognises outstanding posters at a number of conferences. Awardees are invited to share their work with members and this year we are delighted to be able to host the award holders’ talks for members in this online event.

This year’s awardees have all received the WD Wright awards. Abstracts are provided below. 

14:00 Introduction

14:10 Maliha Ashraf (University of Liverpool) Spatio-chromatic contrast sensitivity across the lifespan: interactions between age and light level in high dynamic range

14:35 Yun Chen (University of Leeds) A general colour choosing approach modelling by new research data of designers

15:00 Tea/coffee break

15:10 Yuteng Zhu (University of East Anglia) Designing a color filter via optimization of vora-value for making a camera more colorimetric

15: 35 Ruili He (University of Leeds) Assessing skin colour heterogeneity under various light sources

16:00 End

Please sign up to attend the online event at the eventbrite link below.

For further information concerning this year’s and next year’s awards, please contact the Colour Group Awards Officer: t.l.v.cheung@leeds.ac.uk

ABSTRACTS

Spatio-chromatic contrast sensitivity across the lifespan: interactions between age and light level in high dynamic range

2.10 pm Maliha Ashraf (University of Liverpool)

We investigated spatio-chromatic contrast sensitivity in both  younger and older color-normal observers. We tested how the adapting light level affected the contrast sensitivity and whether there was a differential age-related change in sensitivity. Contrast sensitivity was measured along three directions in colour space (achromatic, red-green, yellowish-violet), at background luminance levels from 0.02 to 2000 cd/m^2, and different stimuli sizes using 4AFC method on a high dynamic range display. 20 observers with a mean age of 33 y.o.a. and 20 older observers with mean age of 65 participated in the study. Within each session, observers were fully adapted to the fixed background luminance. Our main findings are: (1) Contrast sensitivity increases with background luminance up to around 200 cd/m^2, then either declines in case of achromatic contrast sensitivity, or remains constant in case of chromatic contrast sensitivity; (2) The sensitivity of the younger age group  is higher than that for the older age group by 0.3 log units on average. Only for the achromatic contrast sensitivity, the old age group shows a relatively larger decline in sensitivity for medium to high spatial frequencies at high photopic light levels; (3) Peak frequency, peak sensitivity and cut-off frequency of contrast sensitivity functions show decreasing trends with age and the rate of this decrease is dependent on mean luminance. The data is being modeled to predict contrast sensitivity as a function of age, luminance level, spatial frequency, and stimulus size.

A general colour choosing approach modelling by new research data of designers

2.35pm Yun Chen (University of Leeds)

Although many design process studies and design theories were presented, in reality, designers have rarely followed standard rules. A design process is a form of personal self-expression. The type of approach that designers use in their design work depends on their preference, experience and education background. Therefore, this work focused on the design process and colour selection understanding by collecting new research data from the designers and gathering the ideas from their design process to summarise a general colour selection method. This work employs a semi-structured interview approach in a one-to-one interview format to investigate the process of design and collect their colour selection method. A total of twenty designers were interviewed from different design areas, working experience, age groups, cultural background and workplace around Korea, China, South Africa, Mexico and the United Kingdom. Ground Theory method and TF-IDF data analysis method were carried out in interview data analysis. A three-step approach was summarised in this study.

Designing a Color Filter via Optimization of Vora-Value for Making a Camera more Colorimetric

3.10pm Yuteng Zhu (University of East Anglia)

The Luther condition states that if the spectral sensitivity responses of a camera are a linear transform from the colour matching functions of the human visual system, the camera is colorimetric. Previous work proposed to solve for a filter which, when placed in front of a camera, results in sensitivities that best satisfy the Luther condition. By construction, the prior art solves for a filter for a given set of human visual sensitivities, e.g. the XYZ colour matching functions or the cone response functions. However, depending on the target spectral sensitivity set, a different optimal filter is found.

This paper begins with the observation that the cone fundamentals, XYZ colour matching functions or any linear combination thereof span the same 3-dimensional subspace. Thus, we set out to solve for a filter that makes the vector space spanned by the filtered camera sensitivities as similar as possible to the space spanned by human vision sensors. We argue that the Vora-Value is a suitable way to measure subspace similarity and we develop an optimization method for finding a filter that maximizes the Vora-Value measure.

Experiments demonstrate that our new optimization leads to filtered camera sensitivities which have a significantly higher Vora-Value compared with antecedent methods.

Assessing skin colour heterogeneity under various light sources

3.35pm Ruili He (University of Leeds)

Skin colour heterogeneity on human face is related to the perception of youth, health and attractiveness of a human being. This study investigated skin colour heterogeneity in five facial areas (forehead, right cheekbone, left cheekbone, nose tip and chin) under six illuminations with correlated colour temperature (CCT) of 2850 K, 3500 K, 5000 K, 5500 K, 6500 K and 9000 K. Firstly, a facial image capturing protocol was developed to collect facial images from human participants under six different illuminations. Then skin colours in specific facial area were estimated by performing camera colour characterization and transformed to CAM02-UCS colour space. The mean colour difference from the mean (MCDM) with CAM02-UCS colour difference was used to quantify skin colour heterogeneity under different illuminations. The obtained results indicated that larger heterogeneity exists under the light source with lower CCT, and when the CCT of the light source ranges from 5000 K to 9000 K, there was smaller skin colour heterogeneity in each facial area.