Rank based spectral estimation
Lead Research Organisation:
University College London
Department Name: Institute of Ophthalmology
Abstract
Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.
Organisations
People |
ORCID iD |
| Andrew Stockman (Principal Investigator) |
Publications
Bainbridge JW
(2015)
Long-term effect of gene therapy on Leber's congenital amaurosis.
in The New England journal of medicine
Ripamonti C
(2015)
Spectral sensitivity measurements reveal partial success in restoring missing rod function with gene therapy.
in Journal of vision
Ripamonti C
(2014)
Vision in observers with enhanced S-cone syndrome: an excess of s-cones but connected mainly to conventional s-cone pathways.
in Investigative ophthalmology & visual science
Ripamonti C
(2014)
Nature of the visual loss in observers with Leber's congenital amaurosis caused by specific mutations in RPE65.
in Investigative ophthalmology & visual science
Stockman A
(2017)
Hue shifts produced by temporal asymmetries in chromatic signals depend on the alignment of the first and second harmonics.
in Journal of vision
Stockman A
(2017)
Linear-nonlinear models of the red-green chromatic pathway.
in Journal of vision
Stockman A
(2014)
Cone dystrophy with "supernormal" rod ERG: psychophysical testing shows comparable rod and cone temporal sensitivity losses with no gain in rod function.
in Investigative ophthalmology & visual science
Stockman A
(2017)
Hue shifts produced by temporal asymmetries in chromatic signals.
in Journal of vision
Stockman A
(2016)
Handbook of Color Psychology
Stockman A
(2014)
Visual consequences of molecular changes in the guanylate cyclase-activating protein.
in Investigative ophthalmology & visual science
| Description | Human colour perception depends initially on the responses of the long(L-), middle(M-) and short(S-) wavelength-sensitive cones. These signals are then transformed post-receptorally into cone-opponent (L-M and S-(L+M)) and colour-opponent (red/green and blue/yellow) signals and perhaps at some later stage into categorical colour signals. Here, we investigate the transformations from the cone spectral sensitivities to the hypothetical internal representations of 8 colour categories by applying a novel technique known as "Rank-Based Spectral Estimation". Pairs of colours were ranked by 12 observers according to which appeared more representative of eight different colour categories: red-green-blue-yellow-pink-purple-brown-orange. Stimuli comprised circular patches of 32 colours presented on a CRT monitor chosen to cover as large a volume of LMS colour space as possible. In separate blocks, observers judged pairs of colours as to which appeared more like the reference colour name. Pairs for which judgement could not be made, because neither colour appeared like the reference, were recorded but not used. To derive the spectral sensitivities of the colour categories (the 8 "colour sensors") using the rank-based technique, we assumed that the relationship between cone responses and colour appearance can be described by a linear transform followed by a rank-preserving non-linearity. The estimated sensor transformations could account for over 85% of the rank orders. Sensor shapes were generally plausible; those for red and green were consistent across observers, while the yellow and blue ones showed more variability in spectral position. Other sensors, such as brown, pink and purple, showed large inter-observer variability, which might be due in part to cultural differences in colour naming. Sensors were generally restricted to limited regions of colour space. As expected from colour opponent theory, the red and green sensors formed relatively distinct regions with limited overlap as did the yellow and blue ones. Other sensors were spectrally shifted or bimodal. |
| Exploitation Route | We are still writing up and modelling these data. One fruitful new area of research will be to vary colours in the surround or on a background to see how they alter colour sensors operating on a central patch of colour. |
| Sectors | Other |
| Title | CVRL database |
| Description | This web resource provides an annotated database of downloadable standard functions and data sets relevant to colour and vision research and to colour technology, as well as providing information about the research outputs of our group. Updated frequently. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2006 |
| Provided To Others? | Yes |
| Impact | Widely used in science and industry, the site started at UC San Diego in 1995 and moved to UCL with the PI in 2001. |
| URL | http://www.cvrl.org |
| Description | BBC World Service, CrowdScience participant. |
| Form Of Engagement Activity | A broadcast e.g. TV/radio/film/podcast (other than news/press) |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Public/other audiences |
| Results and Impact | CrowdScience participant as an expert on colour vision. |
| Year(s) Of Engagement Activity | 2018 |
| Description | PI was chair and co-chair of the Colour Group GB |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | The Colour Group GB organizes public meetings, school lectures and events on the broad topic of colour. Wider interest and appreciation of the scientific and artistic aspects of colour. |
| Year(s) Of Engagement Activity | 2009,2010,2011,2012,2013,2014 |
| URL | http://www.colour.org.uk |
| Description | Participation in Bloomsbury 2020 Arts festival and production of online visual illusions. Replayed 2021 |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | Production of three visual illusion films for festival as an online presentation because of COVID |
| Year(s) Of Engagement Activity | 2020,2021 |
| URL | https://bloomsburyfestival.org.uk/2020vision/ |
| Description | Public lecture on Human Colour Vision IOP Canterbury |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Professional Practitioners |
| Results and Impact | Public lecture on Human Colour Vision IOP Canterbury |
| Year(s) Of Engagement Activity | 2016 |
| URL | http://www.iop.org |
| Description | Public lecture on Human Colour Vision IOP London |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Professional Practitioners |
| Results and Impact | Colour Vision Public lecture at the Institute of Physics London |
| Year(s) Of Engagement Activity | 2016 |
| URL | http://www.iop.org/ |
| Description | Public lecture on Human Colour Vision IOP Open University |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Professional Practitioners |
| Results and Impact | Colour vision Invited public lecture, Institute of Physics, Open University, Milton Keynes |
| Year(s) Of Engagement Activity | 2016 |
| URL | http://www.iop.org/ |
| Description | Short course instructor, 26th Color and Imaging Conference, Vancouver. |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Class and workshop in colour and colour vision for people in Colour and imaging. Important for forging links with industry. |
| Year(s) Of Engagement Activity | 2018 |
| Description | TEDxUAL talk on Color Vision |
| Form Of Engagement Activity | A broadcast e.g. TV/radio/film/podcast (other than news/press) |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Media (as a channel to the public) |
| Results and Impact | TEDxUAL speaker, University of the Arts London. On-line |
| Year(s) Of Engagement Activity | 2016 |
| URL | http://www.tedxual.com/ |