JP4765236B2 - Color conversion characteristic setting device for image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color conversion characteristic device that sets color conversion characteristics of an image forming apparatus in order to set correction characteristics in an image processing apparatus that corrects image data with correction characteristics corresponding to the color conversion characteristics of the image forming apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an image processing apparatus that corrects image data with correction characteristics according to color conversion characteristics of an image forming apparatus in order to form an image with an original color in an image forming apparatus such as a printer is known. Since the color conversion characteristics of the image forming apparatus vary from product to product or change over time or due to the use environment, the correction characteristics cannot be determined unconditionally. It is necessary to set correction characteristics according to the color conversion characteristics. Therefore, based on the colorimetric values obtained by actually forming a test chart for colorimetry in the image forming apparatus and measuring the color of the test chart with a colorimeter, and the image data of the test chart, the image forming apparatus A technique has been developed for obtaining the color conversion characteristics possessed by and for setting correction characteristics based on the color conversion characteristics.
[0003]
[Problems to be solved by the invention]
However, in order to accurately set the correction characteristics, it is preferable that the number of colors arranged as patches on the test chart is larger (for example, 700 colors or more), and it is necessary to measure colors for each patch. There is also a problem that the work burden is large.
[0004]
Therefore, it is conceivable to convert the color on the test chart into data using an image input device capable of inputting a wide area color at a time, such as an image scanner or a digital camera, instead of the colorimeter. However, while a colorimeter can obtain a colorimetric value that does not depend on the device, such an image input device has a unique color conversion characteristic, so that the image data obtained by these devices depends on the device. Become. In addition, the color conversion characteristics include individual product differences and changes over time, similar to the color conversion characteristics of the image forming apparatus. For this reason, the correction characteristic corresponding to the color conversion characteristic of the image forming apparatus cannot be accurately set using the image input apparatus.
[0005]
The present invention has been made with such a background, and an object of the present invention is to make it possible to easily and accurately set the color conversion characteristics of an image forming apparatus.
[0006]
[Means for Solving the Problems and Effects of the Invention]
In the color conversion characteristic setting device of the image image forming apparatus of the present invention (claim 1) made to solve the above problems, the colorimetric value storage means sets the color conversion characteristic of an external image input device. The colorimetric values of the colors arranged in the standard chart for storing the colorimetric values stored in the colorimetric value storage means and the standard image data obtained by reading the standard chart with the image input device, Are compared by the input characteristic setting means to set the color conversion characteristic of the image input apparatus.
[0007]
Further, in order to cause the image forming apparatus to form a test chart for setting the color conversion characteristics of the image forming apparatus, the test data storage means stores test data for forming the test chart. The color conversion means is based on the set color conversion characteristics of the image input device with respect to the reference image data obtained by causing the image input device to read a test chart formed by the image forming device based on the test data. To perform color conversion processing. Then, the output characteristic setting means sets the color conversion characteristic of the image forming apparatus by comparing the test data with the color information constituting the converted reference image data.
[0008]
That is, in the color conversion characteristic setting device of the present invention, the color conversion characteristic of the image input device is obtained by causing the image input device to read a standard chart in which colorimetric values are acquired in advance. Then, the reference image data that the image input device reads and outputs the color of the test chart actually formed by the image forming apparatus is converted based on the obtained color conversion characteristics. By this conversion, the influence of the color conversion characteristics of the image input device is removed from the converted data (that is, the converted reference image data). Therefore, by comparing the converted image data with the test data, the image forming apparatus The color conversion characteristics can be obtained accurately.
[0009]
Since the image input apparatus can read a color of a wide area in a short time, the color conversion characteristic setting apparatus according to claim 1 can set the color conversion characteristic of the image forming apparatus accurately and easily. Will be able to.
Further, in the color conversion characteristic setting apparatus according to claim 1, the notifying unit includes color information of a predetermined image area of the standard image data and color information of a predetermined image area of the reference image data. Based on the difference between the two, the suitability of both image data is determined, and predetermined information is notified to the outside based on the result of the determination.
That is, it is determined whether the standard image data and the reference image data are suitable for setting the color conversion characteristics of the image forming apparatus, and it is difficult to set predetermined information (for example, accurate color conversion characteristics). A warning to that effect). As a result, the setting of the color conversion characteristics of the image forming apparatus can be prevented from being inaccurate and the state where the user has not noticed that the color conversion characteristics have been performed can be avoided, and the reliability of the color conversion characteristics setting apparatus can be further increased. be able to.
Next, in the color conversion characteristic setting device according to claim 2, the color information of the predetermined image area in the standard image data includes color information of the white area and the black area, and among the reference image data The color information of the predetermined image area includes color information of the white area and the black area.
Next, in the color conversion characteristic setting apparatus according to claim 3 , the first notifying unit determines whether or not the standard image data is appropriate based on the color information constituting the standard image data, and the predetermined notification is performed based on the determination result. Notify external information.
[0010]
That is, it is determined whether the standard image data is suitable for setting the color conversion characteristics of the image input device (and hence the color conversion characteristics of the image forming apparatus), and predetermined information (for example, accurate color A warning that it is difficult to set conversion characteristics). As a result, it is possible to avoid setting the color conversion characteristics of the image forming apparatus to be inaccurate or not being aware of the fact that the color conversion characteristics have been performed incorrectly, and to increase the reliability of the color conversion characteristics setting apparatus. Can do.
[0011]
Further, in the color conversion characteristic setting device according to claim 4 , the second notification means is configured to output the image data (that is, the reference image data or the converted reference) based on the color information constituting the reference image data or the converted reference image data. Appropriateness of the image data is determined, and predetermined information is notified to the outside based on the determination result.
[0012]
That is, it is determined whether the reference image data or the converted reference image data is suitable for setting the color conversion characteristics of the image forming apparatus, and it is difficult to set predetermined information (for example, accurate color conversion characteristics). Warning to the outside). As a result, the setting of the color conversion characteristics of the image forming apparatus can be prevented from becoming inaccurate and the state of not being aware of the fact that the image conversion apparatus has been performed inaccurately, and the reliability of the color conversion characteristic setting apparatus can be further increased. be able to.
[0013]
[0014]
[0015]
In addition, since the standard chart is formed on a predetermined recording medium (for example, printing paper), when creating a plurality of standard charts, they may vary depending on individual differences or changes with time of the devices that create the standard charts. It is difficult to reproduce the same color for all. For this reason, when comparing standard image data obtained for a plurality of standard charts with different colors with a common colorimetric value, the color conversion characteristics of the image input device, and hence the color conversion characteristics of the image forming device. When setting, it will be inaccurate.
[0016]
Therefore, as described in claim 5, identification information is assigned to the standard chart, and the colorimetric value storage means stores the colorimetric values of the standard chart in association with the identification information of the standard chart. The characteristic setting means compares the standard image data obtained by reading the standard chart with the image input device and the colorimetric values stored corresponding to the identification information of the standard chart, thereby obtaining the image input device. It is preferable to configure so as to set the color conversion characteristics.
[0017]
Here, the identification information indicates the identity of the color, and a separate number may be assigned to each standard chart, or a standard number created at the same time by the same device is assigned as a common number. You may do it.
According to the color conversion characteristic setting device according to claim 5 configured as described above, the standard image data obtained by reading the standard chart with the image input device and the identification information of the standard chart are stored. Since the color conversion characteristics of the image input apparatus are set by comparing the measured color values with each other, more accurate setting is possible.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a color conversion characteristic setting device 2 as an embodiment. As shown in FIG. 1, the color conversion characteristic setting device 2 is connected via a network 12 to a computer system 10 that includes an image processing device 4, a printer 6, an image scanner 8, and the like. The computer system 10 functions to cause the printer 6 to perform faithful color reproduction by correcting image data with predetermined correction characteristics in the image processing apparatus 4.
[0019]
The color conversion characteristic setting device 2 of the present embodiment is configured to function to set the color conversion characteristics of the printer 6 in order to set the correction characteristics of the image processing device 4. The printer 6 corresponds to the “image forming apparatus” in the claims, and the image scanner 8 corresponds to the “image input apparatus” in the claims.
[0020]
The color conversion characteristic setting device 2 is configured by a general computer system including a CPU, a RAM, a ROM, an external storage device, and the like, and includes a colorimetric value storage unit 22, an input profile creation unit 24, and a test data storage unit. 26, a color conversion unit 28, an output profile creation unit 30, a first notification unit 32, a second notification unit 34, and a third notification unit 36 are provided.
[0021]
The colorimetric value storage unit 22 stores the colorimetric values (L * a * b * values in this embodiment) of the color arrangement of a standard chart in which various colors are arranged by a large number of patches. . The standard chart 40 is used to set the color conversion characteristics of the image scanner 8, and is distributed with identification information. The colorimetric values stored in the colorimetric value storage unit 22 are obtained by colorimetry before distribution, and in order to be able to identify the corresponding standard chart 40, the identification information of the standard chart 40 and It is associated. The colorimetric value storage unit 22 corresponds to “colorimetric value storage unit” in the claims.
[0022]
The input profile creation unit 24 reads standard image data (RGB values in this embodiment), which is image data obtained by causing the image scanner 8 to read the standard chart 40, and the colorimetric values in the colorimetric value storage unit 22. To set the color conversion characteristics of the image scanner 8. The input profile creation unit 24 corresponds to “input characteristic setting means” in the claims.
[0023]
The test data storage unit 26 stores image data as test data (RGB values in this embodiment) in order to cause the printer 6 to form the test chart 42. The test chart 42 has various colors arranged by a large number of patches, and is used for setting the color conversion characteristics of the printer 6. The test data storage unit 26 corresponds to “test data storage unit” in the claims.
[0024]
The color converter 28 is based on the color conversion characteristics of the image scanner 8 for reference image data (RGB values in this embodiment) obtained by causing the image scanner 8 to read the test chart 42 formed by the printer 6. A color conversion process is performed. The color conversion unit 28 corresponds to “color conversion means” in the claims.
[0025]
The output profile creation unit 30 includes the test data stored in the test data storage unit 26 and the color information constituting the converted reference image data color-converted by the color conversion unit 28 (in this embodiment, L * a * b * Value) is set to set the color conversion characteristics of the printer 6. The output profile creation unit 30 corresponds to “output characteristic setting means” in the claims.
[0026]
Whether the first notification unit 32 is appropriate for setting standard image data, that is, whether the standard image data is suitable for setting the color conversion characteristics of the image scanner 8 (and hence the color conversion characteristics of the printer 6). It is determined whether or not, and the determination result is notified to the outside. The first notification unit 32 corresponds to a “first notification unit” in the claims.
[0027]
Further, the second notification unit 34 determines whether or not the reference image data is appropriate, that is, whether or not the reference image data is suitable for setting the color conversion characteristics of the printer 6, and the determination result is sent to the outside. It is a notification. The second notification unit 34 corresponds to “second notification means” in the claims.
[0028]
The third notification unit 36 determines whether the standard image data and the reference image data are appropriate, and notifies the determination result to the outside. The third notification unit 36 corresponds to the "notification unit" in the claims.
With the color conversion characteristic setting device 2 configured as described above, the color conversion characteristics of the printer 6 are set as follows.
[0029]
First, the user of the computer system 10 causes the image scanner 8 to read the standard chart 40 and transfers standard image data obtained thereby together with the identification information of the standard chart 40 to the color conversion characteristic setting device 2.
Then, the input profile creation unit 24 of the color conversion characteristic setting device 2 reads the colorimetric values corresponding to the standard chart 40 from the colorimetric value storage unit 22 based on the identification information. Then, the input profile creation unit 24 obtains the color conversion characteristics of the image scanner 8 based on the read colorimetric value and the standard image data, and obtains the input profile (RGB value and L * a * b * value). Is set as a lookup table (LUT).
[0030]
The user of the computer system 10 downloads the test data in the test data storage unit 26 from the color conversion characteristic setting device 2 to the computer system 10 and inputs the test data to the printer 6 without performing color correction. A test chart 42 is formed. Then, the test chart 42 is read by the image scanner 8, and the reference image data obtained thereby is transferred to the color conversion characteristic setting device 2.
[0031]
Then, the color conversion unit 28 of the color conversion characteristic setting device 2 converts the RGB values constituting the reference image data into L * a * b * values based on the input profile set by the input profile creation unit 24. To do. Thereby, converted reference image data is generated.
[0032]
The output profile creation unit 30 obtains the color conversion characteristics of the printer 6 by comparing the L * a * b * values constituting the converted reference image data with the test data in the test data storage unit 26, and outputs this. It is set as a profile (lookup table for associating RGB values with L * a * b * values).
[0033]
The output profile created in this way is transferred to the computer system 10, and correction characteristics in the image processing apparatus 4 are set based on this output profile.
For example, as shown in FIG. 2, a patch 44 is formed on the standard chart 40 so that the optical density changes to 0.1, 0.3,..., 2.5. A predetermined gradation appears in a predetermined image area of the image data. As shown in FIG. 3, when the range indicated by A1 is desirable as the recognizable optical density (OD) range, when the range is reduced to the range indicated by A2 due to a decrease in the recognition accuracy of the image scanner 8 or the like, The standard image data is considered not suitable for setting the color conversion characteristics of the printer 6.
[0034]
Therefore, when the standard image data is transferred to the color conversion characteristic setting device 2, the first notification unit 32 sets a predetermined level in a predetermined image area based on color information (RGB values) constituting the standard image data. By determining whether or not the tone appears normally, it is determined whether the standard image data is appropriate, and a warning is notified to the user of the computer system 10 as necessary.
[0035]
The test data is configured such that a gradation patch 46 is formed for each primary color in a predetermined area of the test chart 42. For example, the cyan gradation patch 46 is formed by combining normal cyan ink and light cyan ink, as shown in FIG. Here, for example, when the output amount of normal cyan ink is small, the maximum value of the density of the gradation patch 46 becomes small. When light cyan ink is insufficient, gradation does not appear in the area indicated by B1, and when normal cyan ink is insufficient, gradation does not appear in the area indicated by B2. In such a case, it is considered that the reference image data is not suitable for setting the color conversion characteristics of the printer 6.
[0036]
Therefore, when the reference image data is transferred to the color conversion characteristic setting device 2, the second notification unit 34 sets a predetermined image area in a predetermined image area based on color information (RGB values) constituting the reference image data. It is configured to determine whether or not the reference image data is appropriate by determining whether or not a tone or a predetermined density appears normally, and to notify a user of the computer system 10 of a warning as necessary. ing.
[0037]
In addition, when the color conversion characteristic of the image scanner 8 when the standard chart is read and the color conversion characteristic of the image scanner 8 when the test chart is read are different, the color conversion characteristic of the printer 6 is set accurately. It is difficult. Further, when the recording medium on which the test chart is formed is not appropriate, there is a possibility that the color is not faithfully reproduced on the test chart.
[0038]
Therefore, when the standard data and the reference image data are transferred to the color conversion characteristic setting device 2, the third notification unit 36 performs color information in a predetermined image area (white portion and black portion) of the standard data. And the suitability of the standard data and the reference image data based on the difference between the color information in the corresponding image region (white portion and black portion) of the reference image data, and as a result, if necessary, It is configured to notify the user of the computer system 10 of a warning.
[0039]
As described above, in the color conversion characteristic setting device 2 of the present embodiment, the color conversion characteristic of the image scanner 8 is obtained by causing the image scanner 8 to read the standard chart 40 in which the colorimetric values are acquired in advance. Keep it. Then, the reference image data that the image scanner 8 reads and outputs the color of the test chart actually formed by the printer 6 is converted based on the obtained color conversion characteristics. By this conversion, the influence of the color conversion characteristics of the image scanner 8 is removed from the converted data (that is, the converted reference image data). Therefore, by comparing the converted image data with the test data, the printer 6 Color conversion characteristics can be obtained accurately. Since the image scanner 8 can read a wide area color in a short time, the color conversion characteristics of the printer 6 can be set accurately and easily.
[0040]
In the color conversion characteristic setting device 2 of the present embodiment, whether the standard image data is suitable for setting the color conversion characteristic of the image scanner 8 (and hence the color conversion characteristic of the printer 6). Judgment and notification of predetermined information to the outside. For this reason, it is possible to prevent the setting of the color conversion characteristics of the printer 6 from being inaccurate or from not being aware of the fact that the color conversion characteristics have been performed inaccurately, and the reliability of the color conversion characteristics setting device 2 can be increased. it can.
[0041]
Further, in the color conversion characteristic setting apparatus 2 of the present embodiment, the suitability of the reference image data is determined based on the color information constituting the reference image data, and the predetermined information is sent to the outside based on the determination result. Notice. Therefore, it is possible to avoid the setting of the color conversion characteristics of the printer 6 from being inaccurate or from not being aware of the fact that it has been performed inaccurately, and to improve the reliability of the color conversion characteristics setting device 2. Can do.
[0042]
Further, in the color conversion characteristic setting device 2 of the present embodiment, the color information of the predetermined image area of the standard image data and the color information of the predetermined image area of the reference image data are Appropriateness of both image data is determined based on the difference, and predetermined information is notified to the outside based on the determination result. Therefore, the setting of the color conversion characteristics of the printer 6 can be prevented from being inaccurate, and the state where the user has not noticed that the color conversion characteristics have been performed can be avoided, and the reliability of the color conversion characteristics setting device can be further increased. it can.
[0043]
Further, identification information is assigned to each standard chart 40, and in the color conversion characteristic setting apparatus 2 of the present embodiment, standard image data obtained by reading the standard chart 40 with the image scanner 8, and the standard Since the color conversion characteristics of the image scanner 8 are set by comparing the colorimetric values stored in correspondence with the identification information of the chart 40, more accurate setting is possible.
[0044]
As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, It can take a various aspect.
For example, in the above-described embodiment, the second notification unit 34 has been described as determining whether or not the image data is appropriate based on the color information constituting the reference image data. However, the present invention is not limited to this. It may be configured to determine whether or not the converted reference image data is appropriate based on color information constituting the image data. Even in such a case, the same effect can be obtained.
[0045]
Moreover, although the 3rd notification part 36 demonstrated as what compares the color (color information) of a white part and a black part in the said Example, not only these white and black achromatic colors but a chromatic color may be sufficient. It should be noted that the region to be compared does not matter whether a patch is formed or a ground portion.
[0046]
In the above embodiment, the color conversion characteristic setting device 2 and the image processing device 4 are described as being configured by separate computers and connected by the network 12, but the configuration is not limited to this. For example, the color conversion characteristic setting apparatus 2 and the image processing apparatus 4 may be configured by the same computer, or a color conversion characteristic setting apparatus and a functional part as an image processing apparatus may be incorporated in an image forming apparatus such as the printer 6. good.
[0047]
In the above embodiment, the color measurement value stored in the color measurement value storage unit 22 has been described as using an L * a * b * value, that is, an L * a * b * color system value. However, the present invention is not limited to this, and device-independent color values such as XYZ values, L * u * v * values, Calibrated RGB values, sRGB values, NTSC signal values, and YCbCr values can be used.
[0048]
In the above embodiment, the printer 6 is taken as an example of the image forming apparatus and the color conversion characteristics of the printer 6 are set. However, the present invention is not limited to this. You can also.
In the above-described embodiment, the image scanner 8 is used as the image input device. However, the present invention is not limited to this. For example, a digital camera can be used.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a color conversion characteristic setting device according to an embodiment.
FIG. 2 is a diagram showing a part of a patch on a standard chart.
FIG. 3 is a diagram illustrating a case where the reading accuracy of the image scanner is low (dotted line).
FIG. 4 is a diagram showing a part of a patch on a test chart.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Color conversion characteristic setting apparatus 4 ... Image processing apparatus 6 ... Printer 8 ... Image scanner 22 ... Colorimetric value storage part 24 ... Input profile creation part 26 ... Test data storage part 28 ... Color conversion part 30 ... Output profile creation part 32 ... 1st notification part 34 ... 2nd notification part 36 ... 3rd notification part 40 ... Standard chart 42 ... Test chart

Claims (5)

An apparatus for setting color conversion characteristics of the image forming apparatus necessary for setting the correction characteristics in an image processing apparatus that corrects image data with correction characteristics corresponding to the color conversion characteristics of the image forming apparatus,
For a standard chart for setting color conversion characteristics of an external image input device, colorimetric value storage means for storing colorimetric values of colors arranged in the standard chart;
A color conversion characteristic of the image input device is set by comparing standard image data obtained by reading the standard chart with the image input device and a colorimetric value stored in the colorimetric value storage means. Input characteristic setting means;
Test data storage means for storing image data in advance as test data in order to cause the image forming apparatus to form a test chart for setting color conversion characteristics of the image forming apparatus;
The color of the image input device set by the input characteristic setting means with respect to reference image data obtained by causing the image input device to read a test chart formed by the image forming device based on the test data Color conversion means for performing color conversion processing based on the conversion characteristics;
The color conversion characteristics of the image forming apparatus are set by comparing the test data stored in the test data storage unit with the color information constituting the converted reference image data color-converted by the color conversion unit. Output characteristic setting means;
Based on the difference between the color information of the predetermined image area of the standard image data and the color information of the predetermined image area of the reference image data, the suitability of both image data is determined. Notification means for notifying predetermined information to the outside based on the result of the determination;
An apparatus for setting color conversion characteristics of an image forming apparatus. The color information of the predetermined image area of the standard image data includes color information of a white area and a black area, and the color information of the predetermined image area of the reference image data is a white area. The color information of the black area
  The color conversion characteristic setting device for an image forming apparatus according to claim 1. A first notifying unit is provided for determining whether the standard image data is appropriate based on color information constituting the standard image data, and notifying predetermined information to the outside based on the determination result. color conversion characteristic setting apparatus of an image forming apparatus according to claim 1 or 2. Second notification means for determining suitability of the image data based on the reference image data or color information constituting the converted reference image data, and notifying predetermined information to the outside based on the determination result color conversion characteristic setting apparatus of an image forming apparatus according to any one of claims 1-3, characterized in that it comprises. The standard chart is provided with identification information, and the colorimetric value storage means stores the colorimetric values of the standard chart corresponding to the identification information.
The input characteristic setting unit includes standard image data obtained by causing the image input device to read the standard chart, and a colorimetric value stored in the colorimetric value storage unit corresponding to the identification information of the standard chart. The color conversion characteristic setting device for an image forming apparatus according to claim 1, wherein the color conversion characteristic of the image input device is set by comparing the two.

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