Patent GB-1221841-A (GB)
Title: Combining physical color and subjective color
IPC: G01J3/46
Filed: 1968-03-20
Abstract: 1,221,841. Television. BATTELLE DEVELOPMENT CORP. 20 March, 1968 [24 March, 1967], No. 13485/68. Heading H4F. [Also in Divisions G2, G4 and G5] The invention relates to a method of obtaining higher saturations of colour by combining physical colour with subjective colour produced in accordance with the Fechner-Benham phenomenon which involves the repetition of certain sequences of light and dark areas which are interpreted by the eye and brain as colour. Utilizing this method, signal lights and advertising displays may be arranged to appear in highly saturated hues; physical colour may be combined with subjective colour in motion picture systems or television systems (see Specification 1,083,483); and physical colour may be combined with subjective colour of different hues to produce a mixed hue. To produce subjective colour a Benham-Type disc, Fig. 1A, may be rotated in a clockwise direction at 3À5 to 20 r.p.s., the disc comprising a black opaque section 1, a white sector 2, and red, green and blue creating lines 3, 4 and 5 which appear as reddish, greenish and bluish blur circles, respectively. The exact subjective colour of each line may be determined by comparing it to a colour system such as the colour chips in the Munsell Book of Colours as in Specification 1,221,842. In accordance with the present invention lines 3, 4 and 5 are physically coloured (instead of being black) in the exact same shades in which they appear subjectively. With this arrangement the saturation of the coloured lines when the disc is revolving is a summation of the saturation of the subjective colour and the saturation of the physical colour. Counterclockwise rotation of the disc results in line 3 creating a subjective blue which adds to the physical red of the line to make it appear magneta, similarly line 5 appears magenta (subjective red plus physical blue), whereas line 4 remains green (subjective plus physical green). To extend the physical coloured areas so as to obtain a better ratio of physical colour to white arc areas (such as 6), and thereby to proportionately reduce the white flash and increase the total physical colour saturation thus providing higher saturation for the combined physical and subjective colour, a modified Benham-type disc, Fig. 1B, is used. In Fig. 1B lines 7, 8 and 9 (particularly line 8) have been made longer and black sector 1 of Fig. 1A has been replaced by a physical blue sector 10 and a physical red sector 11. In another method of combining physical colour and subjective colour, coloured lights are used as the physical colour. As shown in Fig. 2, a Benham-type disc 12 with black sector 13, white sector 14 and black arc segment line 15 which creates subjective red when rotated clockwise is flooded with physical red light from lamp 16 in addition to being illuminated by ambient white light. An alternative method is to direct physical red lamp 16 at the eye and the diffusion of red light across the retina causing the black areas to appear red. Another method is to direct lamp 16 at a semi-reflecting surface 16a between the eye and disc 12 and view the combined image of disc 12 and the physical reflected red light. In a further embodiment when a Bidwelltype disc 17, Fig. 3, having a black sector 19, a white sector 20 and a transparent sector 21 through which a display 18 is viewed (white background 22 and physical red colour image 23) is rotated slowly clockwise in front of display 18 and illuminated with white light, image 23 appears a subjective red which combines with its physical red colour. In a further embodiment, Figs. 4A-4G (not shown) a bank of signal lamps are included in a housing, each lamp comprising a back illuminated translucent screen or screens. By switching the lamps ON and OFF in predetermined sequences corresponding to a rotating Benhamtype disc, subjective colour is produced which combines with the colour of the lamps. Since subjective colour is only seen at the edges of the lines such as 3 in Fig. 1 a complex modulation of the light source in increments from full OFF to full ON and back to OFF is necessary to cause the entire area of the eye to create a coloured signal, see Specification 1,229,843 (Division G2). To obtain some colours the lamps are turned on partially, then fully, then partially &c. In a further embodiment a signal lamp having a middle ring which appears as saturated flashing red utilizes a rotating Bidwell-type disc, two white lamps and a red lamp, Figs. 5A-5C (not shown). A further signal lamp, Figs. 6A-6C (not shown), comprises three white light projectors projecting respectively an opaque slide having a physical red translucent caption, a transparent slide having the caption in opaque letters on a translucent white background, and a translucent slide, via a rotating disc with apertures and masks which transmit or block the light from the three projectors in a predetermined sequence causing the caption to appear flashing in highly saturated red on a screen. Alternatively a drum having filter and mask sectors may be rotated around a signal lamp projection housing, Figs. 7A and 7B (not shown). In a further embodiment, Figs. 8A-8C (not shown) the application of the combination of subjective and physical colours to an advertising billboard is described in which coloured lights are turned ON and OFF in predetermined sequences. Figures 10A and 10B illustrate how subjective colour may be added to physical coloured motion picture film or physical coloured television. Four frames which comprise one sequence of subjective colour being added to a physical colour are shown, each frame being divided into colour creating area 98 and surround area 99. In colour creating area 98 the first frame shows stripes 100 of the flag in physical red; the second frame shows flagpole 101 in physical green; the third frame shows star 102 in physical blue; and the fourth frame in opaque. In frames 1, 2 and 3 the outline 103 is black and stripes 104, field 105 and background 106 are white. In this sample, in area 98 this sequence is repeated over and over 6 sequences per second for 24 frames per second sound film projection or 7À5 times per second for a 30 frame television system. Fig. 10B illustrates the reproduced picture the area 98 of which contains highly saturated colour due to the addition of subjective and physical colour.