JP2780258B2 - Multicolor document reader - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor document reading apparatus capable of setting a plurality of colors to be separated. 2. Description of the Related Art In a multicolor document reading apparatus used in a multicolor copying machine or the like, a document reading method for discriminating and separating two or more colors is used. In this multicolor copying machine, particularly in a two-color copying machine, red and black can usually be copied. Therefore, it is not necessary to identify a document other than red and black when reading a document. However, in recent years, there has been a demand that a color other than red, for example, blue, green, etc., be copied in combination with black. In response to this, a plurality of sets of color separation means or color separation parameters are prepared. This is handled by switching. [Problems to be Solved by the Invention] However, when the number of colors to be discriminated / separated increases, there is a problem in that the number of color separation means becomes large and large in number. For example, in order to store parameters, color separation tables are required for the number of colors to be discriminated and separated, which is uneconomical. Also, since the color to be identified and separated is fixed in advance, depending on the original,
Optimal color separation was not always performed. In addition,
There is a drawback that the operability is deteriorated because the number of adjustment points increases. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described drawbacks, and has as its object to provide a multicolor document reading apparatus that can freely set a color to be separated without complicating a color discriminating unit. [Means for Solving the Problems] A multicolor image reading apparatus according to the present invention is a multicolor image reading apparatus that scans and reads an image of a document, identifies the color of the read document, and outputs the identification result. Means for reading a standard color in advance before reading the document, forming an identification area having a predetermined area including a coordinate position based on the saturation and hue on the color separation table, and scanning the document. Means for mapping the obtained color read signal on the color separation table according to the saturation and hue thereof, determining whether the color read signal is included in the identification area, and outputting the determination result. It is characterized by having. [Operation] In the multicolor document reading apparatus, color separation is performed by comparing a color reading signal obtained from the document with a color separation table. In the present invention, the color separation signal should be identified before reading the document. The color is read in advance as a standard color. Then, an identification area is formed on the color separation table based on the read saturation and hue of the standard color.
Next, the original is read and mapped on the color separation table according to its saturation and hue. At this time, if mapped in the identification area, the color of the document is the same as the standard color. That is, by this mapping, color separation is performed based on a standard color given from the outside. [Embodiments] The features of the present invention will be specifically described below based on embodiments with reference to the drawings. First, the schematic configuration of the present embodiment will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a color document reading unit, and an output of the color document reading unit 1 is supplied to a color identification unit 2. The color identification unit 2 includes a mapping RAM. The color reading signals R, G, B from the color document reading unit 1 and the mapping R
The contents of AM are compared and color identification is performed. The operation timings of the color document reading unit 1 and the color identification unit 2 are controlled by the control unit 3, and the control unit 3 may rewrite a threshold or a mapping RAM included in the color identification unit 2. I can do it. In this embodiment, before actually reading the original, the apparatus is set to the color setting reading mode, the color to be identified is set as the original, and the color identification unit setting reading is performed. Thus, the control unit 3 fetches the color reading signals R, G, B from the color document reading unit 1 at this time, and stores the color identification parameters, that is, the threshold value or the table of the mapping RAM based on the data. Set. This makes it possible to externally provide a color to be discriminated and decomposed. FIG. 1 shows an embodiment in which the present invention is applied to a two-color copying machine capable of copying black and one other color. In the circuit shown in FIG.
The circuit on the left side from 28 substantially corresponds to the color original reading section 1 in FIG. 2, and similarly, the circuits on the right side from the subtracters 29a and 29b correspond to the color identification section 2 and the CPU (central processing unit) 32 Substantially correspond to the control unit 3. Here, an operation in the case where a table for color identification and separation has already been set in the mapping RAM 30 by the CPU 32 will be described. The original placed on the platen 21 is irradiated with the light from the lamp 22 and the light reflected by the reflector 23, and the reflected light enters the color image sensor 25 via the lens 24. The color image sensor 25 has three light receiving elements in one pixel, and each light receiving element is covered with three types of filters having different transmission wavelengths, for example, red, green and blue filters. Each color signal obtained by reading one pixel on a document with three different wavelength components can be obtained. The color image sensor 25 is supplied with the clock and timing signals from the sensor drive circuit 26, and scans the document sequentially from the end by a scanner driving device (not shown) when scanning the document. The signal from the color image sensor 25 is sent to the A / D converter 27
After the conversion into a digital signal, the shading correction circuit corrects nonuniform output of the color image sensor 25 due to the optical system and the photoelectric conversion system. The red image signal R ₁ from the shading correction circuit 28 is
With green image signal G ₁ is supplied to the first subtractor 29a, where the difference between G ₂ of both signal levels are determined. Further, image signals R ₁ for red is supplied to the second subtractor 29b with an image signal B ₁ of the other blue and again the difference B ₂ in the signal level is determined. The difference signals G ₂ and B ₂ after the subtraction are stored in the mapping RAM 30.
Supplied to Here, the meaning of performing mapping using the difference signals G ₂ and B ₂ will be described. In the color original reading section 1 with a gray balance, when an achromatic portion of the original, that is, a gray portion is read, the signal levels of the three types of image signals R ₁ , G _1, and B ₁ are obtained. Are the same. As the saturation of the read portion of the document increases, the difference signals G ₂ and B ₂ of the respective image signals R ₁ , G ₁ and B ₁ increase accordingly. If the hue of the read portion of the document changes, the relative levels of the image signals R ₁ , G _1, and B ₁ change accordingly. Therefore, if the difference signals G ₂ and B ₂ are two-dimensionally mapped, the position on the map is determined according to the saturation and hue of the image signal. Therefore, the color identification unit 2 (see FIG. 2)
The signal level of the image signal pair after color separation is subtracted, and two-dimensional mapping is performed by the mapping RAM 30 based on these outputs. Note that the difference signal B ₂ in the horizontal direction (R ₁ −
B ₁ ), the difference signal G _{2 in} the vertical direction (R ₁ -G ₁ in the figure)
And the memory area is divided into four quadrants. Therefore, if you are reading the red on the original, as shown in FIG. 3 (a), will be mapped into the hatched portion M _R of the first quadrant vicinity (indicated by × mark), whereby It can be determined whether the corresponding pixel on the document is red. Incidentally, the hatched portion M _R is as previously described, the table for the color identification decomposition is formed by being set by the CPU 32. The determination signal from the mapping RAM 30 is the image signal G ₁
Is input to the binarization ROM 31. ROM 31 for binarization is
When the mapping RAM 30 identifies that the image signal is not red, the image signal G
₁ is used as a brightness signal to determine white / black, and a final output signal, that is, a 2-bit signal for distinguishing white, black, and red is output. In the above-described example, the identification of red and black has been described. However, when identifying green, black or blue or black on a document, the contents of the mapping RAM 30 are shown in FIGS. 3 (b) and 3 (b). hatched portion M _G of (c), may be respectively rewritten as M _B. This change of the area can be easily realized by setting the apparatus to the color setting reading mode and changing the standard color to perform reading. In addition, other arbitrary colors can be appropriately set in the area from the color distribution diagram shown in FIG. In FIG. 4, (Y), (M), (C), (R),
(G) and (B) show yellow, magenta, cyan, red, green and blue regions, and Y1, Y2... M1, M2.
And the like indicate the distribution of the three primary colors of printing, yellow, magenta, and cyan, and red, green, and blue reproduced by superimposition thereof. Here, the procedure for determining the contents of the mapping RAM 30 as shown in FIG. 3, that is, the table, will be described. In this case, the apparatus is set to the color setting reading mode. In this mode, a standard color original placed at a predetermined position on the platen 21 is read, and the difference signals G ₂ and B ₂
This is the mode to import to PU32. By executing the color setting reading mode, the CPU 32 can recognize the color to be identified and calculate and write the table in the mapping RAM 30. Next, a procedure for calculating a table in the mapping RAM 30 will be described. For example, in FIG. 5, assuming that the difference signals G ₂ and B ₂ in the color setting reading mode are plotted in the X-marked portion on the table, the CPU 32 immediately proceeds to the position d _S ,
to calculate the θ _S. Next, the d ₁ from d _S, from θ _S θ _1, θ ₂
Are calculated respectively. This calculation formula is given, for example, by the following formula. d ₁ = d _C +0.2 (d _S −d _C ) θ ₁ = θ _S −π / 4 θ ₂ = θ _S + π / 4 where d _C is a constant. In this way, the seeking and theta ₁ outside than d _1, the area included in the theta ₂ as the color identification area, by setting the mapping RAM 30, it is possible to identify the color given from the outside. That is, the color identification area in the present embodiment is not fixed. For example, it is optimal to set the color identification area by reading in advance the standard color of the color material of the document to be read and perform color identification based on this. Color separation becomes possible. In this embodiment, the case of a two-color copying machine has been described. However, even in the case of three or more colors, a plurality of colors may be set at different positions on the platen, or a plurality of colors may be set. It is possible to read. Also,
In such a case, the contents of the mapping RAM 30 may be divided into three or more areas instead of two areas. [Effects of the Invention] As described above, in the present invention, a standard color is read in advance before a document is read, and a color separation table is determined based on the standard color. Therefore, it is not necessary to prepare a plurality of tables for color separation independently for each color, and the configuration is simplified. In addition, since a standard color corresponding to the color separation characteristics can be read, optimal color separation can be performed according to the document.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a multicolor image reading apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing a schematic configuration of the multicolor image reading apparatus, and FIG. FIG. 4 is an explanatory diagram showing a state of a table of a mapping RAM for multi-color identification, FIG. 4 is an explanatory diagram showing a state of a table of a mapping RAM for multi-color identification, and FIG. 5 is an explanatory diagram showing a mapping procedure.

Claims (1)

(57) [Claims] In a multicolor image reading device that scans and reads an image of a document, identifies the color of the read document, and outputs the identification result, a standard color is read in advance before reading the document, and based on the saturation and hue of the standard color. Means for forming an identification area having a predetermined size including the coordinate position on the color separation table, and a color reading signal obtained by scanning the original document according to its saturation and hue. Means for mapping the information to determine whether the color reading signal is included in the identification area and outputting a result of the determination.