JP2002120405A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform density regulation appropriately by making inconspicuous the color tone of the CMY mixed color gray patch of a density regulation sheet thereby facilitating comparison with a reference density. SOLUTION: A gray patch D of a reference density printed at an area ratio of regulation density is employed as a substrate and a plurality of square CMY mixed color regulation density gray patches E, arranged vertically and horizontally while varying the area ratio of C and Y to be regulated, are rendered to CMYK mixed color gray patch by further mixing K (in some printer engine, K is added by about 10% in case of 25% patch (each of CMY is 25%)). Since total density is increased by admixing K and color tone is made inconspicuous by merging into the reference density gray patch D of the substrate, the density can be judged easily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly, to an adjustment sheet used for density adjustment (.gamma. Correction) of a reference color constituting a color print output image. The present invention relates to an image forming apparatus provided with a creating unit.

[0002]

2. Description of the Related Art A conventional image forming apparatus will be described by taking a printer as an example. FIG. 1 is a block diagram showing an outline of the configuration of a general printer. Referring to FIG. 1, a user creates data to be printed by a host computer 1,
A printer for printing is designated, and a print command for the created data is issued. On the printer side that receives the print command, when reception of data to be printed is started by the host interface 3 of the equipped printer controller 2, the CPU 4 built in the printer controller 2 based on the transmitted data. Using the program ROM 6, image data to be printed is generated. At this time, the generated image data is stored in the R in accordance with the density specified in the print command.
It is drawn and expanded in the frame memory of AM5. After this,
The image data developed in the frame memory is sent to the printer engine 8 via the engine interface 7, and the printer engine forms an image to complete printing.

In the above-described printer, the density of an image actually formed by a printer engine is changed by a printer controller (that is, the density set by a host computer) due to the surrounding environment and aging. The density may be different from the density of the image data generated by the printer controller in order to obtain a print image of the density. In this case, for example, in a printer including a reading device such as a scanner device, the density is adjusted by providing a printer controller with the following functions. First, the printer controller performs paper output by a printer engine based on image data generated as an image having an intended density value (expected output value) in accordance with print data settings. Next, the image output on paper is read by a scanner device, and the density value (output result) as the read result is compared with the density value (output expected value) intended by the printer controller,
If there is a difference, the density is corrected by performing drawing so as to absorb the difference (for example, the density value is corrected by the printer controller, which is referred to as “γ correction”). The result, that is, the intended result is obtained on the host computer.

On the other hand, in an image forming apparatus not provided with a reading device such as a scanner device, the above method cannot be adopted, so that a print result obtained by outputting a paper based on data in which a predetermined density value (an expected output value) is set is obtained. A method has been studied in which a person visually determines whether the output is dark or light, and inputs an adjustment value based on the determination to a printer controller to adjust the density. When implementing this method, unlike a reading device such as a scanner device, it is difficult for the human eye to determine the density, and to support this, the density value can be read through the human eye using a sheet called an adjustment sheet. It is easy to judge. FIG. 3 shows an example of the prior art relating to this adjustment sheet. In this example, the density to be adjusted is selected within a reference density pattern (part B in FIG. 3) and a predetermined density range around the density pattern including the density. A plurality of drawn adjustment density patterns (A in FIG. 3)
Part) and draw. A reference density pattern (part B in FIG. 3) and a plurality of adjusted density patterns (A (1) to A (A) in FIG. 3)
(8)) means that an adjustment sheet is used in which a circle is divided into a plurality of sectors so as to be juxtaposed and in contact with each other, and reference and adjustment patterns are alternately arranged in each of the sectors. Adjustment density pattern A
(1) to A (8) increase the concentration at a constant rate in eight stages in order,
Numbers (1) to (8) are assigned to each. The adjustment sheet shown in FIG. 3 is output, and a density pattern number having the same density as the reference density is selected from a plurality of drawn density patterns, and the density value (output result) indicated by the number and the intention of the controller are selected. The adjustment value of the γ correction is derived from the density value to be performed (the expected output value), and the γ correction is reflected at the time of drawing to perform the drawing.

In addition, it is necessary to use a pattern which is not affected by aging, machine differences, output conditions, etc., as a reference density pattern in the adjustment sheet used above. For this purpose, the unit (dot) of a pattern (pattern created by arranging dots drawn by a predetermined number of pixels) that creates a predetermined density is not set as one pixel, which is the minimum unit that can be created by the printer engine, and the It has been proposed to make the number of pixels less affected by the output characteristics of the engine. For example, to create a density of 50% of the maximum density of the printer engine, a checkerboard pattern as shown in FIG. 4 may be used. If the dots constituting the pattern are one pixel (dot) of the printer engine,
Since it is affected by the output characteristics of the printer engine, a stable 50% density cannot be created. Therefore, by using a checkered pattern (FIG. 5) in which the constituent points are composed of several dots, a pattern that is not affected by the above-described effect can be created. As described above, the output characteristics, that is, the density can be adjusted even by the printer controller having no reading device.

[0006]

By the way, in the case of a color printer, cyan (hereinafter, also referred to as "C"), magenta (hereinafter, also referred to as "M"), yellow (hereinafter, also referred to as "Y"), etc. Color adjustment other than black (hereinafter also referred to as “K”) must be performed. Each of magenta and black is a single color, and is performed by the density adjustment method using the adjustment sheet shown in FIG. 3 shown in the above-described prior art. For cyan and yellow, the composition ratio is changed to obtain a mixed color gray of cyan, magenta, and yellow. The patch (see the portion E in FIG. 6 described later in detail) is printed out and compared with the black base (refer to the portion D in FIG. 6) indicating the reference density to adjust the density of the four colors. Do. However, in many cases, the CMY mixed-color grays have a tint, and when compared with the K single-color gray indicating the reference density, the user receives a slightly different impression, so that a patch having the same density as the reference is selected. It will be more difficult and will vary depending on the person being tested. The present invention provides such CMY
It was made in view of the problems of the prior art in density adjustment using mixed color gray, and its purpose is to make CMY mixed color gray that makes CMY mixed color inconspicuous and easy to compare with the reference density. An object of the present invention is to provide an image forming apparatus having means for performing a proper density adjustment without causing a variation in the adjustment result by creating a patch.

[0007]

According to a first aspect of the present invention, a plurality of different densities in a predetermined range including a predetermined reference density are represented by a density pattern formed by arranging drawing dots at a predetermined area ratio. Density pattern data generating means for generating adjusted density pattern data, printing means for printing an adjustment sheet based on data of each density pattern generated by the density pattern data generating means, and an adjustment sheet printed with the density of the reference density pattern Wherein the density pattern data generating means comprises a color print output, wherein the density pattern data generating means includes a density adjusting means for adjusting density data of data to be printed in accordance with the adjusted density value detected by the matching of the density of the adjusted density pattern. Of the cyan, magenta, yellow and black reference colors that compose the image, cyan, magenta and yellow As an adjustment density pattern for the density adjustment of one color even without an image forming apparatus, wherein cyan, magenta, yellow, generating a gray density pattern data by mixing black.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the density pattern data generating means includes a reference pattern represented by a density pattern formed by arranging drawing dots at a predetermined area ratio. It is characterized in that density pattern data is generated, and the printing means prints a reference density pattern and a plurality of the adjusted density patterns having different densities on an adjustment sheet.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the printing means alternately arranges a plurality of adjusted density pattern portions having different densities and a reference density pattern portion on the adjustment sheet. And printing.

According to a fourth aspect of the present invention, in the image forming apparatus according to the second or third aspect, the density pattern data generating means generates the reference density pattern data by a black single color whose density has been adjusted. It is characterized by the following.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on the following embodiments shown in the accompanying drawings. Since the printer embodying the present invention can be basically configured in the same manner as the printer shown in FIG. 1, here, the description relating to FIG. 1 described above will be referred to. In this embodiment, basically, the printer of FIG. 1 performs density adjustment of a reference color constituting a color print output image by an adjustment sheet method for creating a mixed color gray patch composed of cyan, magenta, and yellow. FIG. 2 is a view for explaining a basic procedure when such an adjustment sheet system is implemented. According to the procedure shown in FIG. 2, the adjustment sheet is printed out under predetermined printing conditions. A human observes the adjustment sheet printed above, and compares the reference density pattern printed on the adjustment sheet with the adjustment density patterns printed at a plurality of different densities in a predetermined range including the reference density. A density pattern for adjustment which is determined to be the same density as the density pattern is specified (that is, a density value when drawn under the conditions actually used is obtained as a relative value of the reference density). Get the number given. The density value (output result) indicated by the number given to the density pattern for adjustment obtained above is input to the printer as a set value for density adjustment. An adjustment value for γ correction is derived from the number set above (the density value when drawn under the conditions actually used) and the density value (the expected output value) intended by the controller, and the correction result is drawn at the time of drawing. The reflected gamma calculation is performed.

Regarding the adjustment sheet created in the above,
This will be described in detail. FIG. 6 shows an embodiment of the adjustment sheet. In this example, for a density for which a certain adjustment is to be performed, a gray patch having a reference density (part D in FIG. 6, which forms a base in this example) and a predetermined density range including the density are included. A plurality of squares arranged in rows and columns so that gray patches of a plurality of adjusted densities (formed of a plurality of squares in a portion E in FIG. 6) drawn under the conditions selected and actually used are in contact with each other. Are arranged so as to surround each of the E portions of the above with the D portion of the base. The gray patch D having the reference density is composed of K single color. (Note that the reference density pattern is a pattern which is not affected by changes over time, machine differences, or output conditions. The generation method is described above. See description). The gray patches E that are lined up vertically and horizontally are
In the gray patch of CMYK mixed color, M and K are constant, but as shown in the figure, the color is arranged so that the color density increases in the horizontal direction Y to the right, and the color density increases in the vertical direction C in the downward direction It is colored so that it becomes. Each patch of the plurality of adjusted density gray patches E is numbered. The adjustment sheet shown in FIG. 6 is drawn and output, and the number assigned to the gray patch E of the adjusted density CMYK mixed color in which the density is the same as that of the gray patch D of the reference density is selected. The same density is indicated), and is set in the printer as an adjustment value, and is reflected in the γ correction.

FIG. 7 shows an example of the composition ratio (area ratio) of the adjusted density gray patch E and the reference density gray patch D. FIG. 7B shows the adjusted density gray patch E of CMYK mixed color and the reference density of K single color. The composition ratio (area ratio) of the gray patch D is illustrated. FIG. 7A also shows the adjusted density gray patch E of the CMY mixed color of the preceding example. Taking the case of adjusting the density of 25% black as an example, in the printing of the adjustment sheet performed in the preceding example, the K density of the reference density gray patch (the density of the D part in FIG. 6) is 25%, and the CMY The CMY density (density of the E portion in FIG. 6) of the mixed density adjustment density gray patch is 25% for each color. When this is represented by the area ratio, the ratio is as shown in FIG. With the reference density gray patch D printed at this area ratio as the base, as shown in FIG. 6, the composition ratio of C and Y is changed, and square CMY mixed color adjustment density gray patches E arranged in rows and columns are arranged. Place and output drawing. The user obtains the target C and Y composition ratio by selecting the CMY mixed color adjustment density gray patch E that blends with the reference density K gray as the base. However, in the case of this conventional example, the CMY mixed color adjustment density gray patch E has a tint and cannot be dissolved with the base of K gray of the reference density, making it difficult to select a patch of the same density. It comes out.

Therefore, in the present invention, by further mixing K in the CMY mixed color adjustment density gray patch E to increase the overall density and to make the color less noticeable, it melts into the base reference density gray patch D, and When judging that the density is, the judgment is made easy. According to the invention
As shown in FIG. 7B which shows an example of the composition ratio (area ratio) of the CMY mixed color adjustment density gray patch E and the reference density gray patch D, the CMY mixed color gray patch E further includes a CMY mixed color.
K is mixed to form a CMYK mixed color gray patch. FIG. 7 (B)
In the example of FIG. 7A, the concentration is higher by mixing K than in the conventional example of FIG. 7A, but the density value can be adjusted by adjusting the composition ratio. Note that the density of the CMYK mixed color gray patch E after K is mixed (that is,
As shown in FIG. 7 (B), the base K must be raised so that the area ratio is the same, so that the density matches the total density of mixed colors). In addition, when mixing K in addition to CMY, the density value of K to be mixed is expected to differ depending on the size of the tint of the CMY mixed color gray, the density value to be adjusted, and the color distribution of the toner ink. Can not decide. However, it is possible to set a target at the time of design and experimentally find the concentration of K in which the color is inconspicuous. According to the experimental results, one printer engine has a 25% patch (25% for each of CMY).
By adding K about%, a CMYK mixed-color gray patch E with less noticeable color was able to be created.

In the embodiment described above, when the density adjustment of CMY is performed, M is adjusted by the adjustment sheet method for drawing the pattern shown in FIG. 3, and the adjusted composition ratio (area ratio) of M An example in which C and Y are adjusted by the adjustment sheet method for drawing the pattern shown in FIG. From the viewpoint of the visibility at the time of visual judgment, it is preferable that the adjustment sheet for drawing the pattern shown in FIG. 3 is performed with M, but C or Y may be selected instead of M. When the pattern shown in FIG. 3 is drawn by C, M, Y
In the case of drawing by the pattern Y shown in FIG. 3, C and M are adjusted by the pattern shown in FIG. With the adjustment sheet using the CMYK mixed-color gray patches E described above, the adjustment values of the CMY colors in the four-color density adjustment can be accurately obtained. Further, the obtained adjustment value is set in the printer and reflected in the γ correction at the time of the actual printing operation. The γ correction calculation is the same as in the case of the single color. γ
The details of the correction calculation can be implemented by the method described in Japanese Patent Application No. 11-314395.

[0016]

(1) Effects corresponding to the first aspect of the invention: The density pattern of a plurality of adjusted density gray patches on an adjustment sheet drawn for performing density adjustment of at least one color of cyan, magenta, and yellow is cyan. , Magenta,
By generating a gray density pattern by mixing yellow and black, increasing the density of the entire gray density pattern and making the color less noticeable, comparing with the reference density and selecting a patch with the same density as the reference density , So that you can easily select, you can make the appropriate density adjustment,
Image formation without deviation from the density intended by the user can be performed. (2) Effects corresponding to the second aspect of the invention In addition to the effect of the above (1), by printing the reference density pattern and the plurality of adjusted density patterns of different densities on the same adjustment sheet, Since it is not affected by the printing environment such as quality, temperature, and humidity, accurate adjustment is possible. (3) Effects corresponding to the third aspect of the invention In addition to the effect of the above (2), a plurality of adjustment density pattern portions having different densities and a reference density pattern portion are alternately arranged and printed on the adjustment sheet. As a result, when the density of the adjusted density gray patch that makes the color less noticeable and the density of the underlying reference density gray patch match, the density merges with the underlying reference density gray patch, and the same density is selected from among multiple adjusted density gray patches. When selecting density patches,
Since the selection is facilitated, more appropriate density adjustment can be performed, so that an image can be formed without deviation from the density intended by the user. (4) Advantages Corresponding to the Invention of Claim 4 In addition to the advantages of (2) and (3) above, the reference density pattern can be adjusted with high accuracy by generating the density-adjusted black single color. By adjusting the density based on black, it is possible to more accurately adjust cyan, magenta, and yellow.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an outline of a configuration of a general printer.

FIG. 2 is a diagram for explaining a basic procedure when performing density adjustment of a printer by an adjustment sheet method.

FIG. 3 shows an example of an adjustment sheet used for density adjustment.

FIG. 4 shows an example of a 50% reference density pattern printed on an adjustment sheet, in which constituent dots are 1 × 1 pixel.

FIG. 5 shows an example of a 50% reference density pattern printed on an adjustment sheet, in which constituent dots are 2 × 2 pixels.

FIG. 6 shows an embodiment of an adjustment sheet used for CMY density adjustment according to the present invention.

FIG. 7 shows the composition ratio (area ratio) between the adjusted density gray and the reference density gray, and FIG. 7B shows an example of the adjusted density gray of CMYK mixed colors according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Host computer, 2 ... Printer controller, 3 ... Host interface, 4 ... CP
U, 5 RAM, 6 program ROM, 7 engine interface, 8 printer engine, A (1) to A (8) reference density pattern, B
Adjusted density pattern. E: CMY adjustment density pattern, D
… K reference density pattern

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/60 H04N 1/40 D 5C077 1/46 1/46 Z 5C079 F term (reference) 2C061 AP03 AP04 AR01 KK15 KK25 2C262 AA26 AA27 AC03 FA13 2H027 DA09 EB03 EB04 EC03 2H030 AA03 AD16 BB36 5B057 AA11 BA25 CA01 CA08 CA16 CB01 CB16 CE11 CE16 CH11 DB06 DB09 DC32 5C077 LL04 LL17 MM27 MP02 PP02 PP02 PP38 PP38 PP38 PP38 PP38 NA29 PA01 PA02 PA03

Claims (4)

[Claims] 1. A density pattern data generating unit that generates adjusted density pattern data representing a plurality of different densities in a predetermined range including a predetermined reference density, based on a density pattern formed by arranging drawing dots at a predetermined area ratio. Means, printing means for printing an adjustment sheet with data of each density pattern generated by the density pattern data generating means,
An image forming apparatus comprising: a density adjusting unit that adjusts density data of data to be printed according to an adjusted density value detected by matching the density of the reference density pattern with the density of the adjusted density pattern on the printed adjustment sheet; The density pattern data generating means includes a cyan, magenta, yellow, and black reference colors that constitute a color print output image, and adjusts the density of at least one of cyan, magenta, and yellow. An image forming apparatus for generating gray density pattern data based on a mixture of magenta, magenta, yellow, and black. 2. The image forming apparatus according to claim 1, wherein said density pattern data generating means generates reference density pattern data represented by a density pattern formed by arranging drawing dots at a predetermined area ratio. The printing unit prints a reference density pattern and a plurality of adjustment density patterns having different densities on an adjustment sheet. 3. An image forming apparatus according to claim 2, wherein said printing means prints a plurality of adjustment density pattern portions having different densities and reference density pattern portions on an adjustment sheet alternately. An image forming apparatus comprising: 4. An image forming apparatus according to claim 2, wherein said density pattern data generation means generates the reference density pattern data in a black color of which density has been adjusted. Forming equipment.