Patent GB-1390977-A (GB)
Title: System for analyzing multicoloured scenes
IPC: G01J3/46
Filed: 1972-08-29
Abstract: 1390977 Colour image reproduction ITEK CORP 29 Aug 1972 [3 Sept 1971] 39965/72 Heading H4F A system for producing a diagrammed work surface to assist an artist in the creation of an original painting of a colour scene, e.g. a colour photograph, the work surface being of the type described in Specification 1,366,724, and ineluding outline marks identifying detail boundaries in addition to zone marks which divide the work surface into separate zones each of which is identified with a number (or other mark), corresponding to the paint colour to be applied, i.e. a "paint-by-number" surface including sharp detail boundaries is produced, wherein the system includes an optical scanner, a gradient detector and a colour analyser. The diagrammed work surface may be used for oil or water-colour painting, needlework, mosaicwork, object recognition for map making, classification of aerial photographs or determination of water depths, the analysis being effected with visible or infra-red sensors. Each colour scene is first standardized, e.g. into a frame on a 70 mm. transparency strip 132, Fig. 6, so that all the scenes are of uniform size and tone. Computer control marks 138 are recorded adjacent each frame together with mailing information 134 and colour control information 135 and 136. The standardizer includes a photographic camera (Fig. 7, not shown), with corrective filters (e.g. neutral density and red and blue filters), a movable cropping platen, and a comparison arrangement in which an input scene is compared with a plurality of standard scenes associated with predetermined pallettes of different coloured paints until the standard scene with the nearest colour hues is found, e.g. the standard is found having similar (facial) colours to that of the scene (portrait) to be created. The colour control blocks 136 identify the particular set of colour domains, i.e. volumes in a 3D colorimetric system (e.g. a brightness, hue and saturation system), to be used in the subsequent analysis of the transparency 133, and also the corresponding pallette of paints. Since variations may occur in the colour temperature of the lamp (178, Fig. 8, not shown), caused by ageing or voltage variations, which is used to display the standard scenes (177) for comparison with the input scene (164) (fibre optics (173, 175) and a split eyepiece (166) being used), a record of the condition of the lamp (178) is made on the transparency as the colour control patch 135. Each transparency on the resulting strip 132 of Fig. 6 is analysed in stepped film transport 55, Fig. 4, the analysing light beam 62 being scanned back and forth across the film by a reciprocating scanning mirror 65 and being passed via an apertured beam splitter 73 into a gradient detector 25 and a colour analyser 26. The diagrammed work surface is specifically produced photographically in a photo-sensitive paper stepped transport 58 scanned by the same reciprocating mirror 65 with a combined beam 106<SP>1</SP> which includes the polarized output of laser 88 which is continuously modulated by the output of gradient detector 25 in electro-optic modulator 86, and also the output of a light source 99 which is intermittently energized to print the zone marks and associated identification numbers. Modulator 86 only passes light when a detail boundary in the transparency is sensed, at all other times beam 92 is extinguished. The outputs of the red, green and blue photo-cells 85, 83 and 77 are compared with the corresponding signals which identify each of the selected colour domains, and thus paints to be used. Thus for each zone the colour domain (and therefore paint colour), within which the analysed colour lies, is selected and an appropriate output used to actuate light source 99. Light source 99 includes 16 flashtubes located behind an apertured mask 321, Fig. 19, which has zone mark producing apertures 305a and 306a, and zone colour identifying number producing apertures 307a-320a. The colour analysis of the transparency is effected in a ten-fold dot interlace manner, i.e. during one scan the colour of the areas "1" in Fig. 22 are analysed, there are for example 100 such areas spanning the transparency strips, and compared as above to produce the zone marks and zone identifying numbers. These zone marks and numbers are then (if different from the adjacent area colour), recorded on the work surface (photo-sensitive paper), during the next scan when the areas "2" are analysed. The "numbers" are only recorded if the zone marks are recorded so that a number only occurs in the upper left corner of each region of a particular colour no matter how large or small this region is, i.e. only when a zone boundary is detected. The comparison of the analysed signals with the selected set of colour domain signals to determine the nearest, is timed with the aid of a clock 117, Fig. 4, actuated by a portion of the beam from laser 88, the clock comprising a photo-multiplier disposed behind an apertured mask (Fig. 20, not shown), across which the laser beam is scanned by the scanning mirror 65. The interlace analysis is controlled by pulses derived from the computer in which the zone marks are stored for subsequent recording (print-out). The gradient detector (Fig. 11, not shown), comprises an aperture divided into quadrants, the light received in each quadrant being directed via respective light guides to four photodetectors which are paired diametrically so that any difference between the outputs of each pair indicates a detail boundary. The reciprocating scanning (two-sided), mirror 65 is driven by two loudspeakers operated in push-pull, their cones being coupled to opposite ends of a lever bar centrally connected to the mirror's shaft (Fig. 10, not shown).