US3858044A - Recognition of colors by photo-sensitive means - Google Patents

Recognition of colors by photo-sensitive means Download PDF

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Publication number
US3858044A
US3858044A US00413371A US41337173A US3858044A US 3858044 A US3858044 A US 3858044A US 00413371 A US00413371 A US 00413371A US 41337173 A US41337173 A US 41337173A US 3858044 A US3858044 A US 3858044A
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coordinates
axes
loci
separating
point
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P Frappe
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Staeubli Verdol SA
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Verdol SA
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/46—Measurement of colour; Colour measuring devices, e.g. colorimeters

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  • the present invention relates to the photo-electronic recognition of colors, or more exactly of coloring dyes, particularly for the reading-in of the designs used in the preparation of perforated cards or papers for loom jacquards.
  • the procedure may frequently be simplified by considering the projections of the loci on the planes determined by the axes of the system of coordinates.
  • the loci are then formed of plane figures corresponding to a pair of primary colors in each plane and the separating figures become straight lines (or successions of portion of straight lines).
  • the electronic circuitry is thus greatly simplified. But it may occur that some loci overlap each other in all the planes though they are in fact separated from each other in the space which corresponds to the system of.coordinates.
  • the system of coordinates is changed in the space and the loci are projected on the planes determined by the axes of the new system, the latter being selected in such manner that the projections of any pair of loci do not overlap each other in all the said planes.
  • the new system of coordinates may further be so se lected that one at least of the planes determined by its axes may form a separating figure between the loci.
  • this plane divides the loci into two groups respectively situated on one and the other side of the said plane and which may thus be differenciated from each other even if their projections overlap in that plane.
  • FIG. 1 shows the representative curve of a coloring dye versus the wave length of the reflected light.
  • FIG. 2 illustrates the loci of the colors of a design in the simplest case of two colors which may be satisfactorily analysed by means of only two wave lengths.
  • FIG. 3 shows how the two colors of FIG. 2 may be discriminated from each other by changing the system of coordinates.
  • FIG. 4 corresponds to a modification of FIG. 3.
  • FIG. 5 shows in the case of two colors how the space may be divided into two semi-spaces the loci thus being themselves divided into two groups.
  • FIG. 6 indicates how the locus of a color may be projected on a plane perpendicular to the trisectrix of the three coordinate axes in the case wherein the colors are analysed by means of three wave lengths.
  • FIG. 7 illustrates the projections thus obtained in the case of a design having seven colors.
  • FIG. 8 shows how a three-dimensional space may be divided into two semi-spaces by means of an appropriate plane in order that the loci of the colors may be themselves divided into two different groups.
  • FIG. 9 is a diagram illustrating how the coordinates of a new system may be electronically deduced from those of the former one.
  • FIG. 10 shows how a hyperplane in a fourdimensional space may be electronically represented.
  • FIG. 11 is a simplified diagram corresponding to the case wherein the hyperplane is perpendicular to the quadrisectrix of the coordinate axes.
  • FIG. 12 illustrates a more complicated diagram corresponding to a number of successive operations.
  • any coloring dye may be analysed by being illuminated by a white light, the intensity of the light reflected being plotted versus its wave length. There is thus obtained a curve such as N (FIG. 1) which is representative of the dye. Since in actual practice the use of all the portions of such curves for the discrimination of the colors of a design or other support would lead to excessive complications the coloring dye is merely identified by the respective intensities y y y Ofa limited number of analysing wave lengths I A It The photo-sensitive devices (photo-electric cells and their circuitry) are further so arranged that ordinate corresponds to the white color of the support (this color being assumed to be perfect), the reflected intensities y y y then appearing in the form of percentages.
  • the first step consists in determining the characteristics of each dye (or mixture of dyes) used in the design.
  • the number of analysing wave lengths used should be as reduced as possible taking into account the similarities of the dyes. In order to simplify the explanations it will first be assumed that only two wave lengths are used, though this is quite exceptionally possible.
  • FIG. 2 therefore illustrates two coordinate axes Ob-Or corresponding to two analysing wave lengths, respectively blue and red, these axes being graduated from zero to 100 in order to represent the intensities of the reflected light of the colored portions of the design as percentages of the white light reflected by the support thereof.
  • the center 0 corresponds to a black spot (no light reflected) and point M to a white spot (blue and red reflected equally to the maximum possible).
  • the design only comprises two colors C, and C If the coloring dyes used were perfect and if their density on the white paper or like support were sufficient and quite uniform, the responses of the photo-electric cells for all the spots of the drawing would be represented by one of the two points C and C But in actual practice the composition of a commercial dye varies within certain limits between successive batches and therefore for a given density the representative point may be situated within a curve 0 c more or less similar to a circle having its center respectively at C C A3 to the unavoidable variations in the density of application of the dye on the paper, it must be assumed that they remain between reasonable limits and under such conditions their effect is to extend the circle more or less towards M and O.
  • each dye is a surface S,, S delimited by a more or less banana-shaped curve s1, s2.
  • this disadvantage is avoided by changing the system of coordinates. It is more particularly possible, as indicated in FIG. 3, to select for the new axes the bissectrix OM and a straight line X'OX perpendicular to the latter. It may easily be ascertained that the projections of S, and S, on the new axis X'X (or on a plane perpendicular to the plane of FIG. 3 and containing X'X) are formed of two segments sla-slb, s2a-s2b which are spaced from each other and are thus easily discriminated electronically. The projections s'la-slb, s2a-s2b on OM overlap each other, but this is of no importance since discrimination is obtained along axis X'X.
  • FIG. 4 illustrates a case wherein the loci 8,, S are such that they cannot be safely separated by the bissectrix OM. It is then generally possible to find another straight line AP which passes between the said loci. This line may be selected as one of the new axes of coordinates, the other X'OX being perpendicular to AP.
  • axis X'X may remain spaced from the center of the initial coordinates.
  • FIG. 5 shows for instance a case wherein owing to the number of colors of the design (two only of which are represented by loci 8,8,), the system of coordinates has been changed from bOr to XO,X-YO,Y, the loci being projected on axis X'OX.
  • the projections of the loci may be perfectly spaced from each other and easily separated by straight lines. It is more particularly possible to so select these new axes that one of the said planes be substantially perpendicular to the n-sectrix of the angle formed by the initial axes.
  • the loci of the coloring dyes must be represented in a threedimensional space with three axes Ob, 0], Or which may be illustrated in perspective as indicated in FIG. 6.
  • the trisectrix is then the line OM which joins the black point 0 and the white point M.
  • X designates a plane perpendicular to OM; this plane may be considered as defined by two of the three axes of a new system of coordinates.
  • the various loci 8,, S etc (only S, is illustrated in FIG. 6) are projected on that plane, as indicated at S, for locus S,.
  • plane X contains point M but this is of course immaterial.
  • FIG. 7 shows how the projections S, to S, of seven loci may appear in plane X as more or less regularly distributed around point M. It is generally easy to separate these projections by straight lines. If two projections overlapped in plane X the angle of the latter with respect to OM could be somewhat varied to obtain their separation provided this variation causes no overlapping of other loci.
  • FIG. 8 shows how the loci may be divided into two groups by means of an appropriate plane in a threedimensional space.
  • this plane X is substantially perpendicular to OM, as plane X of FIG. 6, but with this difference that its position along OM should be carefully selected.
  • the loci are preferably projected on this separating plane X rather than on a different plane X.
  • the separating The coefficients a c characterize the new system. If in the latter the axes are perpendicular to each other, there coefficients follow the relations:
  • this plane is then a so-called hyperplane" having three dimensions.
  • the problem remains as above, but with four coordinates (.r, y, z, t or u, v, w, r) instead of only three and with sixteen coefficients a (1 If the hyperplane is perpendicular to the quadrisectrix of the four axes of the four-dimensional system, then each of the three axes of this hyperplane is itself perpendicular to the said quadrisectrix. Assuming these three axes correspond to three of the four axes of the new system, then:
  • the dividing plane is a hyperplane defined by an equation such as:
  • Such an equation may be represented by means of an operationalamplifier 34 (FIG. 10) having five inlets to receive the analogs x, y, z, I, E of the responses of the four analysing cells (one for each wave length), and of coefficient E itself. If properly adjusted this amplifier will yield an outlet-analogically equal to Ax By Cz 01+ 1 X E. If the spot being analyzed were in the hyperplane, the outlet value L would be zero. If the spot is on one side of this hyperplane L will be positive while if the spot is on the other side, L will be negative.
  • reference 35 designates an inverter which permits of directly obtained E.
  • the dividing hyperplane may be defined in the new system (coordinates u, v, w, r). If one of the axes of the new system is parallel to the quadrisectrix and if the dividing hyperplane is perpendicular to the letter, then its equation becomes:
  • the hyperplane may be represented by an operational amplifier 36 (FIG. 11) having only two inlets to receive respectively r and k.
  • FIG. 12 illustrates by way of example the block diagram of an electronic discriminating apparatus for four analysing wave lengths (responses x, y, z, I of the four corresponding cells), wherein the coordinates are changed (new coordinates u, v, w, r), the projections of the loci being discriminated in the plane v-w by means of three separating straight lines A1, A2, A3, and with the four-dimensional space being divided by two hyperplanes P1, P2 perpendicular to the quadrisectrix.
  • Operational amplifiers 37, 38, 39, 40 determine the new coordinates.
  • Amplifiers 41 and 42 correspond to planes P1, P2, while the pairs 43, 44 and 45 represent straight lines Al, A2, A3.
  • outlets of the various devices are selectively applied to the five inlets of a number of AND gates such as 46, 47 each corresponding to the colors C 1, C2, etc. of the design (two only being shown in FIG. 12).
  • the outlets of these gates individualize each of these colors.
  • the spot being analysed is of color Cl if it corresponds to a locus situated above Al and A2, but below Pl while for a spot of color C2 the locus should be below A1,. above A3, above P1 and below P2, the terms above and below only corresponding to the positive or negative character of the outlet of devices 41 to 45.
  • each of said circuits means receiving inlet signals corresponding to the coordinates of a point in said one of said planes and each emitting an outlet sig nal at a predetermined level when said last-named point is part of the separating line, at a level above said predetermined level when said last-named point is situated on one side of said last-named separating line, and at a level below said predetermined level when said last-named point is on the other side of said last-named separating line;
  • n axes of said first system of coordinates having a n sectrix and said one plane being substantially perpendicular to said n sectrix.
  • analogically representing said separating figure by electronic circuit means having means for receiving inlet signals corresponding to the coordinates ofa point in said second system and in response to said inlet signals emitting an outlet signal at a predetermined level when said Iast-named point is part of said separating figure, at a level above said predetermined level when said last-named point is situated on one side of said separating figure, and at a level below said predetermined level when said last-named point is on the other side of said separating figure;
  • said first system of coordinates having a n-sectrix and said separating figure being perpendicular to said n-sectrix.
  • said first and second system of coordinates being tri-dimensional, each pair of their three axes defining a plane, and said separating figure being a separating plane parallel to one of the planes defined by a pair of axes of said second system.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectrometry And Color Measurement (AREA)
US00413371A 1973-02-02 1973-11-06 Recognition of colors by photo-sensitive means Expired - Lifetime US3858044A (en)

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3942154A (en) * 1973-07-06 1976-03-02 Agency Of Industrial Science & Technology Method and apparatus for recognizing colored pattern
US4075604A (en) * 1976-02-23 1978-02-21 Tasco S.P.A. Method and apparatus for real time image recognition
US4089644A (en) * 1973-04-13 1978-05-16 Sandoz Ltd. Method and apparatus for regulating the rate of dye adsorption by the number of dye liquor cycles
US4110826A (en) * 1975-10-07 1978-08-29 Dr. -Ing. Rudolf Hell Gmbh. Apparatus and process for color-identification
US4191940A (en) * 1978-01-09 1980-03-04 Environmental Research Institute Of Michigan Method and apparatus for analyzing microscopic specimens and the like
WO1994025838A1 (fr) * 1993-04-29 1994-11-10 Centre De Recherche Industrielle Du Quebec Procede et appareil permettant de detecter des couleurs d'articles et de classer ces derniers
US5751834A (en) * 1996-02-07 1998-05-12 Basf Corporation Image analysis method for determining pigment levels in fabric
US6057931A (en) * 1993-07-12 2000-05-02 Mci Telecommunications Corporation Method and apparatus for controlling color image reproduction

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3647295A (en) * 1969-05-23 1972-03-07 Crosfield Electronics Ltd Color printing apparatus
US3752590A (en) * 1970-11-30 1973-08-14 Verdal S A Automatic recognition of colors

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3647295A (en) * 1969-05-23 1972-03-07 Crosfield Electronics Ltd Color printing apparatus
US3752590A (en) * 1970-11-30 1973-08-14 Verdal S A Automatic recognition of colors

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4089644A (en) * 1973-04-13 1978-05-16 Sandoz Ltd. Method and apparatus for regulating the rate of dye adsorption by the number of dye liquor cycles
US3942154A (en) * 1973-07-06 1976-03-02 Agency Of Industrial Science & Technology Method and apparatus for recognizing colored pattern
US4110826A (en) * 1975-10-07 1978-08-29 Dr. -Ing. Rudolf Hell Gmbh. Apparatus and process for color-identification
US4075604A (en) * 1976-02-23 1978-02-21 Tasco S.P.A. Method and apparatus for real time image recognition
US4191940A (en) * 1978-01-09 1980-03-04 Environmental Research Institute Of Michigan Method and apparatus for analyzing microscopic specimens and the like
WO1994025838A1 (fr) * 1993-04-29 1994-11-10 Centre De Recherche Industrielle Du Quebec Procede et appareil permettant de detecter des couleurs d'articles et de classer ces derniers
US6057931A (en) * 1993-07-12 2000-05-02 Mci Telecommunications Corporation Method and apparatus for controlling color image reproduction
US5751834A (en) * 1996-02-07 1998-05-12 Basf Corporation Image analysis method for determining pigment levels in fabric

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Publication number Publication date
DE2404201B2 (de) 1977-02-24
FR2216567A2 (fr) 1974-08-30
DE2404201A1 (de) 1974-08-22
JPS571621B2 (fr) 1982-01-12
JPS49107783A (fr) 1974-10-14
FR2216567B2 (fr) 1977-07-22

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