JPH0486689A - Method for constituting color correcting sample - Google Patents

Abstract

PURPOSE:To lessen the adverse influence that the unequalness of a color correcting sample on the same recording paper surface arising from the nonuniformity of image recording characteristics exerts on color correction processing by arranging color patches while shifting the arranging sequence thereof from each other between two sets among plural pieces of the color samples. CONSTITUTION:The color correcting samples 2 is formed by outputting plural pieces of the color samples 13a to 13d including the same number of the plural color patches arranged in the prescribed arranging sequence in the horizontal and vertical direction of the recording paper 11, etc., and is arranged with the color patches which are shifted from each other between two sets among plural pieces of the color samples 13a to 13d. Then, plural pieces of the color patches of the same color eventually exist at the different places on the recording paper 11 surface and, therefore, plural pieces of the colorimetric values to a specific color are obtd. by measuring the colors of these color patches. The calculating of the average of these colorimetric values is then possible. The colorimetric value having high reliability is obtd. by calculating the average of these colorimetric values. The influence that the local nonuniformity of the recording characteristics at the time of the formation of the sample images exerts on the reliability of the color samples 13a to 13d is lessened in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for configuring a color correction sample created on recording paper during color correction processing in a digital color copying machine or the like.

[Prior Art] Conventionally, image forming apparatuses such as digital color copiers and color printers that output multi-tone color images have been used to convert nonlinear recording characteristics caused by the image forming means to near-linear characteristics. In order to correct this, it was necessary to perform color correction processing. At this time, in order to investigate the original recording characteristics of the image forming device, a color sample consisting of color patches (small rectangular areas in which set colors are recorded) of dozens to hundreds of colors is created. A method was used in which the recorded color of the sample was measured by outputting the color sample and having the color sample read by an image reading device or the like. When creating a color sample for this color correction process, a set of dozens to hundreds of color patches is created on recording paper, and these multiple color patches are arranged vertically and horizontally in an appropriate order. By doing so, a color correction sample was constructed.

[Problems to be Solved by the Invention] Generally, in image forming means using an electrophotographic method, non-uniformity of recorded images occurs on the recording paper surface due to various factors. For example, there are density unevenness caused by charging unevenness caused by dirt on the corona wire of the charger in the direction along the charger, and density unevenness caused by streaks during development in the recording paper transport direction.

Therefore, in the conventional color correction sample construction method described above,
Since there are no color patches on the recording paper surface, only specific color patches are affected by image unevenness due to non-uniformity of the recorded image on the recording paper surface, which is caused by the inherent recording characteristics of the image forming device. The color patch will be recorded in a different color than the original color. As a result, the created color sample is
This has resulted in low reliability as a specimen required for measuring the original recording characteristics of an image forming apparatus, and has become a factor that hinders accurate color correction processing.

The present invention has been made in order to solve the above-mentioned problems, and in the method of configuring a color correction sample created for color correction processing in a digital color copying machine, etc., various factors of the image forming means are considered. It is an object of the present invention to provide a method of configuring a color correction sample that can reduce the adverse effects on color correction processing caused by unevenness of the color correction sample on the same recording paper surface caused by non-uniformity of image recording characteristics due to non-uniformity of image recording characteristics.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for configuring a color correction sample consisting of a set of a plurality of color patches to be output on recording paper or the like for color correction processing. A color correction sample consists of a plurality of output color samples containing the same number of multiple color batches arranged in a predetermined arrangement order in the horizontal and vertical directions of a recording paper, etc. At least two sets of color samples are arranged differently from each other.

[Operation] According to the above method, there are multiple color patches of the same color at different locations on the recording paper surface of the color correction specimen, so by colorimetrically measuring these color patches, a specific color can be determined. A plurality of colorimetric values for each color are also obtained, and the average of these colorimetric values can be calculated. By using this average value as the specimen colorimetric value, a highly reliable colorimetric value can be obtained, and the influence of localized non-uniformity of recording characteristics during specimen image formation on the reliability of the color specimen. can be reduced. In addition, since the color patches of each of the multiple color samples are arranged in different horizontal and vertical order on the recording paper, the color patches of each of the multiple color samples are arranged in different orders in the horizontal and vertical directions. This prevents only a specific color patch from being unevenly recorded due to unevenness in the specimen image that occurs along the recording paper conveyance direction due to streaks caused by the developing device, etc. .

[Embodiment] FIG. 1 shows a block configuration of a digital color copying machine that performs color correction processing using a color correction sample according to an embodiment of the present invention.

The digital color copy I11 includes an image forming section 3 consisting of an engine section of a laser printer that prints the color correction sample 2 on recording paper, an image scanner 4 that reads the color correction sample 2, and a color measurement unit of the read color correction sample 2. It is composed of a CPtJ5 that calculates colorimetric values for color correction processing based on values, and a memory 6 that stores colorimetric value data read for this calculation.

This copy Ill has a resolution of 400 by the image forming section 3.
This digital color copying machine 1 is a digital image forming apparatus capable of recording images on A3 recording paper at a dot/inch (dpi <dots/inch), and is the target of color correction processing.

Figure 2 shows a color correction sample 2 constructed according to the construction method of the present invention.
FIG. 3 is a diagram showing an example of the arrangement of color patches constituting the same color correction sample 2. FIG.

The vertical and horizontal dimensions of the recording paper 11 on which the color correction sample 2 is printed are as follows:
As shown in Figure 2, w = 4677 dots (
Approximately 297m+), H=6614 dots (Approx. 420m+)
). The color correction sample 2 is composed of four color patch sets 13a, 13b, 13c, and 13d on the recording paper 11.
3c and 13d are arranged so as to be in contact with each other in two rows and two columns vertically and horizontally.

The color correction sample 2 is recorded on the surface of the recording paper 11 so that it is separated from the top edge of the recording paper 11 by a top margin TM and from the left edge by a left margin LM. TM,
LM is determined by selecting a value such that the color correction sample 2 is located near the center on the surface of the recording paper 11. Here, LM
= 410 dots (approximately 26 m+) and TM = 420 dots (approximately 27 meters). The reason for doing this is that in the edge area of the recording paper 11, there is a possibility that the color correction sample 2 will be recorded with recording characteristics different from the original recording characteristics due to various characteristics of the image forming section 3. Therefore, the color correction sample 2 is made to avoid covering such edge areas as much as possible.

As shown in FIG. 3, each color batch set is constructed by arranging a total of 216 color patches, 18 rows and 12 columns in each direction, in contact with each other in both directions. The horizontal and vertical dimensions of each color batch are 160 dots x 160 dots (approximately 10+m+x10). In the following, to avoid confusion in terminology, each color patch set will be referred to as a color sample, and as shown in FIG. 2, the horizontal direction of the recording paper 11 will be the X direction, and the vertical direction will be the Y direction.

Furthermore, a method for arranging color patches within a color sample will be explained in detail. An address is assigned to each color patch within the color sample. In other words, j in the X direction?
The recorded color as a color sample of the i-th color patch in the Y direction is S (t, j) (i=1.
,,． 18; j go 11 becomes HH1.

A method for determining the recording color Sa (i, j) of each color patch of the color sample 13a using the above color patch arrangement method will be described. This applies to other color samples, such as 13b in Figure 1.
You can decide on 13c or 13c first, but for the sake of explanation,
The color sample 13a will be determined first. This determination method is based on the image forming unit 3 of the digital color copy I11.
This is carried out by changing the density of each basic color toner of cyan, magenta, and yellow recorded by stepwise, and simply extracting all combinations of them one after another and assigning them to the recorded colors as the color sample 13a. be exposed. In other words, when the recording densities of cyan, magenta, and yellow toners are Ci, Mj, and Yk, respectively, ((Ci, Mj, Yk) l (i=1
．． ,,． 6; Jl+, +6; k=1. ,,． 6
) represents a set of 216 sample colors. Here, CI
, MJ, and Yk may be changed arbitrarily, but considering the characteristics of a color correction sample, it is recommended to include the minimum and maximum recording densities of each recording color and divide them at appropriate intervals. It is preferable to adopt it.

The 216 sample colors selected in this way are Sa <
L 1) = (CI, Ml, Yl) Sa (
L2)=(CI, Ml, Y2)Sa (
1,6)=(CI, Ml, Y6)Sa
(1,7) = (CI, M2, Yl
) Sa (18, 11) = (C6, M6, Y
5) Sa (18, 12>= (C6, M6
, Y6), the recording color is set for the color patch to which the address shown in FIG. 3 is assigned. By this method, the recorded color of the color patch for the color sample element 13a is determined.

Next, a method for determining the recording color Sb (i, J) of the color sample 13b will be explained with reference to FIGS. 4 and 5. This is the recorded color 5 of the color patch of the color sample 13a mentioned above.
It is constructed by sequentially shifting the recorded color in the row by one patch in the X direction for each row patch in the Y direction based on a(i, J). In other words, if i≠12, Sb (i, j) = Sa (i, (i+j-1
) mod12+1) (1=11-0,18; j=11.,.12
)1=12, then Sb (i, J)= Sa (i, (i+j)1
The recording color Sb (i, j) of the color patch is set as follows: 10d12+1) (1=12; j=1.,.12). In the above formula, nod represents the remainder operator. FIG. 4 shows how the color pads are arranged.

Here, an exception is made for the color patch line of 1=12, that is, the 12th line, because the color patch line is the color sample 13a.
This is to avoid an arrangement that is equal to that of .

By determining the recorded colors of the color patches for the color sample 13b using this method, each color patch row of the color sample 13b has a layout in which the recorded colors of the color patches in that row are all different from that of the color sample 13a. This alleviates the effect of image unevenness caused by charging unevenness along the X direction on the surface of the specimen recording paper 11 only on the recorded color of a specific color patch.

A method for determining the recording color SC(t, J) for the color sample 13C is derived from the same concept as for determining the recording color Sb (t, j) for the color sample 13b. This is the recorded color 5a (of the color patch of the color sample 13a mentioned above).
i, j), for each row batch in the X direction, the recorded colors in the row are sequentially shifted by one patch in the Y direction. In other words, Sc (i, J) = Sa ((i+j
-1) Il.

d18+l,j) (i =1.,,.18; j l,,,12
), set the recording color sc (, i, j) of the color patch. FIG. 5 shows how the color patches are arranged.

By determining the recorded colors of the color patches for the color sample 13C by such a method, each color patch row of the color sample 13C has the arrangement of the recorded colors of the color patches in that row all different from that of the color sample 13a. This reduces the influence of image unevenness caused by streaks along the Y direction on the surface of the specimen recording paper 11 only on the recorded color of a specific color patch.

Finally, the recorded color Sd<t,j) for the color sample 13d
uses one having the same configuration as the recorded color 5a (i, j) of the color batch of the color sample 13a.

That is, Sd (i, j) = Sa (i, j) (i =
1. ,,． 18; j = 1. ,,． 12) The reason for this is that the position of the color sample 13d on the recording paper 11 is placed at different positions in both the X and Y directions in this embodiment. This is because it is determined that there is no particular need to rearrange the color patches.

The color correction sample 2 configured as described above is read by the image scanner 4 to obtain the same recorded color (C
i, Mj, Yk), four colorimetric values are obtained for each recorded color. When performing colorimetry, it is necessary to take into account that the recorded colors of color patches are rearranged according to the color sample according to the above-mentioned rules.

The colorimetric values of the color patches for these four recorded colors (Ci, Mj, Yk) are calculated using the color sample 1 that includes the color batch.
Ra, R corresponding to 3a, 13b, 13c, 13d, respectively.
b, Rc, Rd, R(1, J, k>=(Ra
(i, J, k) + Rb (i, j, k) + Rc (t, j, k) + Rd (i, j, k))/4 (i=1.,,.6; j=1. ,,.6; k=
1. ,,． 6), the recorded colors (Ci, Mj
, Yk) is obtained.

Thus, by using the color correction sample 2 consisting of color patches arranged differently between the color samples as described above,
The colorimetric value of the recorded color of color correction sample 2 is
It is possible to perform accurate color correction processing based on this colorimetric value.

Note that although an example using four color samples has been described above, the present invention is not limited to this, and any number of color samples may be used. Further, the color samples do not necessarily need to be arranged in a grid, and the arrangement may be changed as appropriate.

[Effects of the Invention] As explained above, when color correction processing is performed using a color correction specimen according to the configuration method of the present invention, non-uniformity of image recording characteristics due to various factors of the image forming means is caused. It is possible to avoid unevenness of color correction samples on the same recording paper surface that causes biased embellishment values, which reduces the negative effect on color correction processing and allows for accurate color correction processing. It can be carried out.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of a digital color copying machine that performs color correction processing using a color correction sample according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of the same color correction sample, and FIG. 3 is a diagram showing a set of color correction samples. FIGS. 4 and 5 are diagrams illustrating color samples configured by shifting the recorded colors of color patches, respectively. 2... Color correction sample, 3... Image forming unit, 4... Image scanner, 11... Recording paper, 13a, 13b
, 13c, 13d... color patch set (color sample), S.
・Color patch. Applicant: Brother Industries, Ltd. Agent Patent Attorney: Yasushi Itatani Numbers represent j in 5a(i,j) Numbers represent i in 5a(i,j)

Claims (1)

[Claims] (1) In a method for configuring a color correction sample consisting of a set of a plurality of color patches to be output on recording paper, etc. for color correction processing, the color correction sample is arranged in a predetermined manner in the horizontal and vertical directions of the recording paper, etc. It is composed of a plurality of output color samples containing the same number of color patches arranged in an array order, and the arrangement order of the color patches is arranged differently between at least two sets of the plurality of color samples. A method of constructing a color correction specimen characterized by the following.