PowerPoint Presentation by HC120311094824

VIEWS: 0 PAGES: 24

									             DAVID ALAN PALMER
                July 1933 - June 2000




COLOUR
GROUP (GB)
             Christ’s College, Hendon Lane, Grammar School
             Imperial College - physics, 1952 - 1955
             Imperial College - PhD, 1958: supervisor W.D. Wright
             National Physical Laboratory - 1958
             National Physical Laboratory - W.S. Stiles
COLOUR
GROUP (GB)
             NPL - general duties including photometry
             NPL - Brian Crawford & colour rendering
             NIC - chair of colour rendering committee 1965-7
             IoO - Institute of Ophthalmology, 1967
COLOUR
GROUP (GB)
             MESOPIC PHOTOMETRY




COLOUR
GROUP (GB)
             MESOPIC PHOTOMETRY

             “The equivalent luminance L of any light may be
             expressed, to a good approximation, as a
             function of its scotopic and photopic luminances.”
                LP   E1( )  V ( )  d
                LS   E 2 ( )  V '( )  d
             The question is, “What is this function?”
             David measured scotopic and photopic luminances
             by matching test lights of different wavelengths to
             white light of 2042K
             At match, LV, the equivalent luminance follows the
             relation:
                LP  LV  LS
             and the scotopic and photopic luminances can be
COLOUR       calculated and log LP plotted against log LS
GROUP (GB)
COLOUR       David’s plot of log LP against log LS
GROUP (GB)
             Palmer said that ideally the plots should show,
             “straight lines parallel to the P axis at very low
             levels, and parallel to the S axis at high levels.”
             But additivity was not perfect so there were
             departures from this especially at the ends
             of each curve.

             The data fitted adequately
             the expression:

                           MS  P 2
                L(S, P ) 
                            M P
             which is the form that
             the Palmer Mesopic
             Model is usuall set out:
             the figure shows how
             well the data fit the
COLOUR       relation
GROUP (GB)
             Data from other workers fitted the model well considering
             the problems know to exist with additivity - here are data
             from Kinney, JOSA, 58:1296, 1968
COLOUR
GROUP (GB)
             Christmas Celebrations
             David was known for celebrating Christmas in style - a
             chosen theme, usually Dickensian, was followed for food,
             drink and decor




             and the lab had the benefit of last
             years decorations, for example,
             celebrations with Captain Cuttle
             from Dombey and Son
             In this David revealed high talent as
             an artistic draughtsman
COLOUR
GROUP (GB)
             ENTOPTIC PHENOMENA - in art the light source was
             seldom depicted because glare, halos and contrast ratios
             are not easy or possible to capture convincingly




COLOUR
GROUP (GB)
             A search for halos and glare showed many artists capturing
             the drama of light and shade but hiding the source




COLOUR
GROUP (GB)
             COLOUR RENDERING


                                This was the first of a
                                long series of papers
                                on colour rendering
                                and . . . .




                                 . . . the effects of new
                                fluorescent lamp
                                phosphors on clinical
                                evaluation of patients and
COLOUR                          skin lesions
GROUP (GB)
             COLOUR RENDERING
                                And this was the
                                last set of papers
                                in the series




COLOUR
GROUP (GB)
             COLOUR RENDERING




             For this work the team were awarded the Walsh-Western
             Bronze Medal of the Chartered Institute of Building Services
             Engineers in 1993


COLOUR
GROUP (GB)
             RETIREMENT
             In the ninties David retired and then worked afternoons at
             the University of Westminster
             There we had fun with sunglare protection (i.e. sunglesses)




             We evaluated sunglasses for
             magazines and checked for safety a
             whole range of toys which contained
             laser light sources




COLOUR
GROUP (GB)
             Traffic signal light recognition involved sorting out the
             infamous Q Factor




             and doing experiments on signal colour recognition




COLOUR
GROUP (GB)
             CHRISTMAS again....and the sloe gin recipe competitions
             continued as did the search for the perfect microwave
             oven baked Christmas Pud




             David continued his work, started with Brian Crawford
             years before, on luminosity functions
COLOUR
GROUP (GB)
             David showed normal observers’ photopic luminosity
             functions for large fields fell into one of three groups




COLOUR
GROUP (GB)
             David measured protanopes’ scotopic luminosity functions
             and showed they were reduced at long wavelengths -
             evidence that scotpic vision is a mix of rod and L wavelength
             cone inputs




COLOUR
GROUP (GB)
             David re-analysed the original scotopic luminosity function
             data of Crawford which had been used to formulate the CIE
             internationally agreed curve and found some surprises: many
             curves were considerably narrower than the CIE curve and the
             peak wavelengths were grouped as shown below




COLOUR
GROUP (GB)
             David started to re-measure these curves with modern
             equipment but had to know about pre-retinal absorption so we
             set about measuring the macular pigment

                                           We made many
                                           prototypes with David’s
                                           favourite material - card &
                                           UHU glue
                                           Six instruments of the final
                                           design were made and are
                                           used across Europe



             It was whilst calibrating
             one of these that David
             was taken ill - he never
COLOUR       worked again
GROUP (GB)
             PROMOTION OF SCIENCE
             David hated the way the Government treated science and
             scientists, and was appalled at the general lack of
             understanding of science, especially by those “educated” elites
             that made up various authorities
             He worked to improve the understanding of science with, e.g.
             the Institute of Physics and the Royal Institution




COLOUR
GROUP (GB)
             James Clerk Maxwell - a model and hero




COLOUR
GROUP (GB)
             DAVID PALMER vision scientist 1933-2000




COLOUR
GROUP (GB)

								
To top