JP2009038664A - Color processing apparatus, and method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To map the pixel values of a multi-band image outside an area reproducible by an output device in the area. <P>SOLUTION: A table of the prescribed number of dimensions is composed of table data showing a correspondence relation between a multi-band pixel value and a signal value to be outputted to an output device (S302). Whether the multi-band pixel values of an inputted multi-band image are within an area reproducible by the output device is determined with reference to the table (S304). When the result of the determination shows that the values are within the reproducible area, a signal value to be outputted to an output device corresponding to the multi-band pixel value is calculated with reference to the table (S306). In addition, when the result of the determination shows the values are outside the reproducible area, the number of dimensions of the table data is gradually decreased to reconfigure the table (S305 and S302). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to spectral color reproduction.

  When displaying or printing the image data acquired from the image input device on the image output device, in order to perform faithful color reproduction, based on the three primary color theory, using conditional color, the input tristimulus values and output Colorimetric color reproduction that matches tristimulus values is performed. The CIEXYZ color system and CIELab color system defined by the CIE (International Commission on Illumination) are used as the space where the tristimulus values are quantified.

  FIG. 1 is a block diagram showing the configuration of a general colorimetric color reproduction system.

  An RGB image acquired by an image input device such as a digital camera is subjected to image processing in a device-independent XYZ space or L * a * b * space, and is output to an image output device as an RGB or CMY image.

  Since the XYZ and L * a * b * values are affected by the illumination light source, even if the subject color and the reproduced color match the XYZ and L * a * b * values under a certain illumination light source, the illumination light source If it is different, the value will be completely different. As a result, the subject color and the reproduced color are perceived as different colors. Therefore, in the field of color management, it is desired to realize spectral color reproduction as a more faithful color reproduction method. According to spectral color reproduction, the spectral reflectance itself of an object that does not include an illumination light source is reproduced as color information. Therefore, the subject color and the reproduced color can be made equal under an arbitrary illumination light source.

  Multiband input / output technology is expected as a technology for realizing spectral color reproduction. Colorimetric color reproduction is based on the three primary colors such as RGB and CMY, whereas multiband input / output technology obtains object color information using four or more primary colors and reproduces the spectral reflectance. Technology. As an image input device, development of a multiband camera having four or more bands is underway (for example, Patent Document 1). In addition, development of multiband output devices has been promoted by the development of multi-primary projectors and the practical use of multi-primary printers (for example, Patent Document 2).

  FIG. 2 is a block diagram showing a spectral color reproduction system using a multiband input / output device.

  The spectral color reproduction system captures a subject with a multiband input device, and acquires image data having a spectral reflectance as a value of each pixel (hereinafter, spectral image, spectral image data, or multiband image). Next, image storage, processing, and transmission are performed in a spectral space that does not depend on the device and the illumination light source. The spectral image is reproduced by a multiband output device.

  When the visible light region 380 to 730 nm is sampled every 10 nm, the spectral reflectance becomes one-dimensional 36-dimensional data, and the spectral image has a very large amount of data. In other words, in order to completely reproduce the spectral image, it is necessary to make all 36-dimensional data equal. In fact, except for special cases, it is difficult to make all 36-dimensional data equal. In other words, if a 36-dimensional spectral image is processed, it is outside the region that can be reproduced by the image output device (the spectral reflectance region, but here called the color gamut). Therefore, in the spectral color reproduction system, how to reduce the amount of data and how to map the spectral image data to a color that approximates the spectral reflectance becomes an issue.

  To solve this problem, the principal component analysis is performed on the spectral image, and the spectral reflectance data is represented by the principal component vector and its addition rate (hereinafter referred to as the principal component coefficient), thereby reducing the amount of spectral reflectance data. A technique for processing a spectral image in a multidimensional space of principal component coefficients is known. That is, a method of performing mapping processing of the colorimetric color reproduction system in a multidimensional space of principal component coefficients is conceivable.

  For example, Patent Document 3 calculates a corresponding output signal value by changing a principal component coefficient of each dimension at equal intervals in a principal component coefficient space, and shows a look-up table indicating a correspondence relationship between the principal component coefficient and the output signal value. (LUT) is created. And the method of converting the principal component coefficient of a spectral image into an output signal value with reference to LUT is disclosed.

  However, since the method of Patent Document 3 receives as input a spectral image in which spectral reflectance data is stored in each pixel, it requires enormous calculation to convert spectral reflectance data of all pixels into principal component coefficients. In addition, it is necessary to create an LUT by searching for output signal values corresponding to principal component coefficients arranged at equal intervals from all output signal values, and it takes a lot of time to create the LUT. Further, it does not consider how to process data outside the output color gamut of the image output device.

JP 2001-086383 A JP 2001-054131 A JP 2002-254708 JP

  An object of the present invention is to map pixel values of a multiband image outside the reproducible region of the output device into the region.

  The present invention has the following configuration as one means for achieving the above object.

  The color processing according to the present invention inputs a multiband image, constructs a table having a predetermined number of dimensions from table data indicating a correspondence relationship between a multiband pixel value and a signal value output to an output device, and refers to the table If the multiband pixel value of the input multiband image is within a region that can be reproduced by the output device, and the determination result indicates the region within the reproducible region, the table is Referring to this, when the signal value output to the output device corresponding to the multiband pixel value is calculated and the determination result indicates outside the reproducible region, the number of dimensions of the table data is decreased stepwise. Then, the table is reconstructed.

  According to the present invention, pixel values of a multiband image outside the reproducible region of the output device can be mapped in the region.

  Hereinafter, color processing according to an embodiment of the present invention will be described in detail with reference to the drawings.

[Overview]
The multiband input device outputs a multiband image composed of pixel values of a plurality of bands. Hereinafter, the pixel value of the image data output from the multiband input device is referred to as “multiband pixel value”. In this embodiment, an LUT that associates this multiband pixel value (input data) with a signal value (output data) to be output to a multiband output device is created, and the multiband image is converted into an output image.

  At the time of this conversion, there is a problem of how to process multiband pixel values outside the region that can be reproduced by the multiband output device (hereinafter referred to as an output color gamut). FIG. 3 is a diagram for explaining a space corresponding to a multiband pixel value, and shows a two-band two-dimensional space for simplicity.

  As shown in FIG. 3, when a multiband pixel value outside the output color gamut is input, it must be replaced with a multiband pixel value within the output color gamut. However, it is very difficult to calculate a replacement value in a multiband multidimensional space. Therefore, until the input data enters the output color gamut, the number of bands of the input data is decreased stepwise to calculate the replacement value.

  In the example of FIG. 3, reducing the number of bands means projecting in one of the axial directions. In the case of FIG. 3, there are two ways of projecting in the axial direction of band 1 or in the axial direction of band 2, but comparing the result of projecting the axial direction of band 1 with the result of projecting in the axial direction of band 2, It is preferable to select a replacement value close to the input data.

[Device configuration]
FIG. 4 is a block diagram illustrating a configuration example of the spectral color reproduction device 31 of the embodiment.

  The spectral color reproduction device 31 inputs a multiband image from a multiband input device (hereinafter, input device) 32 such as a multiband camera. Then, an output image obtained by converting the multiband image into a signal value for a multiband output device (hereinafter, output device) 33 such as a multiband printer is output to the output device 33.

  In the spectral color reproduction device 31, the input unit 14 inputs a multiband image from the input device 32. The output unit 35 outputs an output image to the output device 33. The input image storage unit 16 stores the input multiband image. The output image storage unit 17 stores the output image converted from the multiband image. The input image storage unit 16 and the output image storage unit 17 are storage devices such as a hard disk (HD). The LUT storage unit 18 is a memory device such as a RAM or an HD that stores table data for converting a multiband image into an output image.

  The band selection unit 19 extracts table data of a specified band from the table data and stores it in the LUT buffer 20 such as a RAM. The interpolation processing unit 21 performs an interpolation process for converting a multiband pixel value into an output signal value. The inside / outside determination unit 22 determines whether or not the multiband pixel value is within the output color gamut. The output signal selection unit 23 uniquely determines the output signal value when a plurality of output signal values are calculated. The spectral reflectance estimator 24 estimates the spectral reflectance from the multiband pixel value. The error calculator 25 calculates an error between the input spectral reflectance and the output spectral reflectance.

  The above components are connected to each other via a system bus 13 and are connected to a control unit 11 such as a one-chip microcontroller that controls the entire spectral color reproduction device 31.

  In the following, an inkjet printer that uses six-color multiband cameras as the input device 32 and six color materials of cyan C, magenta M, yellow Y, black K, orange O, and green G as the output device 33 will be described. To do.

  In addition, the control unit 11 controls the input device 32 to photograph a subject using a predetermined number of filters having different transmission wavelengths, and inputs pixel values corresponding to the filters as multiband pixel values. For example, if a multiband image is acquired using six filters whose transmission wavelengths are arranged at almost equal intervals, a six-dimensional spectral image (multiband image having six main components) is acquired.

[processing]
FIG. 5 is a flowchart showing the processing of the spectral color reproduction device 31.

The control unit 11 controls the input device 32 via the input unit 14, acquires a multiband image and stores it in the input image storage unit 16 (S201), and sets a counter i indicating the pixel position to 1 (S202). ). As will be described in detail later, an output signal value corresponding to the multiband pixel value at the pixel position i is calculated (S203). In this embodiment, image data whose pixel position is represented by coordinates (x, y) is coordinate-converted using equation (1) and handled as a one-dimensional array.
i = y × ysize + x… (1)
Here, ysize is the number of pixels in the horizontal direction of the image.

  Next, the control unit 11 stores the output signal value at the pixel position i in the output image storage unit 17 (S204), and calculates the output signal value for all the pixels of the multiband image stored in the input image storage unit 16. It is determined whether or not (S205). If there is a pixel whose output pixel value has not been calculated, the counter i is incremented (S207), and the process returns to step S203.

  When the output signal values are calculated for all the pixels, the control unit 11 outputs an output image composed of the output pixel values stored in the output image storage unit 17 to the multiband output device 33 via the output unit 15 (S206). ) To form an image.

Calculation of Output Signal Value FIG. 6 is a flowchart showing details of the process (S203) for calculating the output signal value.

  The control unit 11 sets a predetermined number (for example, 6) to the variable n indicating the number of search dimensions (S301). As will be described in detail later, the band selection unit 19 is controlled to select, for example, a low-order n band from among six bands (delete the high-order band) to create an LUT and store it in the LUT buffer 20. Store (S302). Note that the input of the n-band LUT is a multiband image having n dimensions. That is, by limiting the number of dimensions constituting the LUT, the number of dimensions of the multiband image used for calculating the output signal value is reduced, and the amount of data in the calculation is reduced.

  Next, as will be described in detail later, the control unit 11 controls the inside / outside determination unit 22 to determine whether the multiband pixel value at the pixel position i is included in the output color gamut indicated by the LUT stored in the LUT buffer 20 or not. Is judged whether inside or outside (S303). If the multiband pixel value at the pixel position i is outside the output color gamut, the variable n is decremented (S305), and the process returns to step S302. That is, by reducing the number of dimensions stepwise and reconstructing the LUT, the number of dimensions of the multiband image used for calculating the output signal value is also reduced stepwise.

  When the multiband pixel value at the pixel position i is in the output color gamut, the control unit 11 controls the interpolation processing unit 21 to calculate an output signal value (in other words, an output signal value mapped in the output color gamut) ( S306). As will be described in detail later, when a plurality of output signal values are calculated, the output signal selection unit 23 is controlled to uniquely determine the output signal value (S307).

[Band selection part]
The band selection unit 19 selects a band corresponding to the number of search dimensions n from the table data stored in the LUT storage unit 18 and creates an LUT. For example, when selecting 3 bands from 6 bands, there are 6C3 = 20 combinations. For all these combinations, an LUT indicating the relationship between the multiband pixel value (input data) that is n-dimensional data and the output signal value that is m (m ≦ n) -dimensional data is created and stored in the LUT buffer 20. Remember.

[Inside / outside judgment part]
The inside / outside determination unit 22 performs inside / outside determination by extending tetrahedral interpolation in a multidimensional manner. FIG. 7 is a flowchart showing details of the inside / outside determination (S304).

  Although the details will be described later, the inside / outside determination unit 22 selects a multidimensional tetrahedron from the table data stored in the LUT storage unit 18 (S401). Then, the inside / outside determination processing in the selected multidimensional tetrahedron is performed (S402), and it is determined whether or not the multiband pixel value at the pixel position i is in the selected multidimensional tetrahedron (S403). If the multiband pixel value at the pixel position i is within the selected multidimensional tetrahedron, the multiband pixel value at the pixel position i is within the output color gamut, and the process ends.

  Further, when the multiband pixel value at the pixel position i is outside the selected multidimensional tetrahedron, the inside / outside determination unit 22 determines whether the inside / outside determination has been performed for all the multidimensional tetrahedrons configured by the LUT data (S404). . If there is a multidimensional tetrahedron that has not been determined, the process returns to step S401. Further, when the inside / outside determination is performed for all the multidimensional tetrahedrons, the multiband pixel value at the pixel position i is outside the output color gamut, and the processing ends.

  A multidimensional tetrahedron is an extension of a three-dimensional tetrahedron to multidimensional.

● Internal / external determination in multidimensional tetrahedron The internal / external determination of multidimensional tetrahedron in the internal / external determination unit 22 will be described in detail. The input point P of the multidimensional tetrahedron is expressed by equation (2).
↑ OP = a ₀・ ↑ Q ₀ Q ₁
+ a ₁ ↑ Q ₀ Q ₂
+…
+ a _n-1 ↑ Q ₀ Q _n-1
+ ↑ OQ ₀ … (2)
_{Here, P (p 0, p 1} , ..., p n-1) is input point,
O (0, 0,…, 0) is the origin,
Q ₀ (q _{0, 0} , q _{0, 1} ,…, q _{0, n-1} ),…, Q _n-1 (q _{n-1, 0} , q _{n-1, 1} ,…, q _{n-1 , n-1} ) is each vertex of the multidimensional tetrahedron,
↑ represents a vector.

Expression (3) is a necessary condition that the input point P exists in the multidimensional tetrahedron.
0 ≤ a ₀ + a ₁ +… + a _n-1 ≤ 1
And
a ₀ ≥ 0, a ₁ ≥ 0, ..., a _n-1 ≥ 0 ... (3)

Expression (3) can be represented by a matrix like Expression (4).
[p ₀ p ₁ … p _n-1 ]
= [q _{1, 0} -q _{0, 0} q _{1, 1} -q _{0, 1} … q _{1, n-1} -q _{0, n-1} ] [a ₀ a ₁ … a _n-1 ] ^T
+ [q _{0, 0} q _{0, 1} … q _{0, n-1} ]… (4)
Here, T represents a transposed matrix.

Next, [a ₀ a ₁ ... A _n−1 ] ^T can be calculated from the equation (5) by regression analysis.
[a ₀ a ₁ … a _n-1 ] ^T
_{= ([Q 1, 0 -q} 0, 0 q 1, 1 -q 0, 1 ... q 1, n-1 -q 0, n-1] T
[q _{1, 0} -q _{0, 0} q _{1, 1} -q _{0, 1} … q _{1, n-1} -q _{0, n-1} ]) ^-1
[q _{1, 0} -q _{0, 0} q _{1, 1} -q _{0, 1} … q _{1, n-1} -q _{0, n-1} ] ^T
[p ₀ -q ₀ p ₁ -q ₁ … p _n-1 q _n-1 ]… (5)

The inside / outside determination of the multidimensional tetrahedron can be made depending on whether or not [a ₀ a ₁ ... A _n−1 ] calculated by Expression (5) satisfies the condition of Expression (3). That is, if the expression (3) is satisfied, the input point P is in the multidimensional tetrahedron, and if not satisfied, the input point P is outside the multidimensional tetrahedron.

[Output signal selector]
FIG. 8 is a flowchart for explaining output signal value selection (S307) by the output signal selector 23.

  The output signal selection unit 23 uses the spectral reflectance estimation unit 24 to convert the multiband pixel value at the pixel position i into spectral reflectance (hereinafter referred to as input spectral reflectance) (S501). Then, using the table data stored in the LUT storage unit 18, a multiband pixel value corresponding to each of the plurality of output signal values is calculated (S502).

  Next, the output signal selection unit 23 uses the spectral reflectance estimation unit 24 to convert the multiband pixel value calculated in step S502 into a spectral reflectance (hereinafter, output spectral reflectance) (S503). Then, the error calculation unit 25 calculates the difference (error) between the input spectral reflectance and the output spectral reflectance (S504).

  The calculation of the error may be an RMS (root-mean-square) error between the input spectral reflectance and the output spectral reflectance, a color difference, or a metameric index. Note that ΔE, ΔE94 or ΔE2000 is used to calculate the color difference.

  Next, the output signal selection unit 23 determines whether or not errors for all of the plurality of output signal values have been calculated (S505), and if not completed, the process returns to step S502. If the error is calculated for all the plurality of output signal values, the output signal value with the smallest error is selectively output (S506).

  As described above, when the input multiband image is spectrally reproduced by the output device, an LUT in which the multiband pixel value is associated with the output signal value is created. When a multiband pixel value outside the output color gamut is input, the number of bands of the LUT is changed, and the multiband pixel value outside the output color gamut is mapped within the output color gamut.

  The color processing according to the second embodiment of the present invention will be described below. Note that the same reference numerals in the second embodiment denote the same parts as in the first embodiment, and a detailed description thereof will be omitted.

  In the second embodiment, a user interface (UI) is used to read a multiband image and table data, and further specify an error calculation method for determining a unique output signal value from a plurality of output signal values.

  FIG. 9 is a block diagram illustrating a configuration example of the spectral color reproduction device 31 according to the second embodiment. 4 differs from the configuration shown in FIG. 4 in that the spectral color reproduction device 31 of the second embodiment stores an error calculation method storage unit 26 that stores an error calculation method, an RGB conversion unit 27 that converts spectral reflectance into device RGB, and a user interface. This is to have a UI unit 28 that displays a face (UI) on the monitor 34.

[UI]
FIG. 10 is a diagram illustrating an example of a UI displayed on the monitor 34 by the UI unit 28.

  The input image display unit 701 displays the multiband image converted into the RGB image by the RGB conversion unit 27. The output image display unit 702 displays an output image.

  An input image edit box 703 is a box for describing a path name of a multiband image to be input. The LUT edit box 704 is a box for writing a path name of table data. The error calculation method radio button 705 is a button for selecting an error calculation method.

  The error display unit 706 displays the error calculated by the error calculation unit 25. A read button 707 is a button for instructing a process of reading each data. The execution button 708 is a button for instructing conversion processing into an output signal. A print button 709 is a button for instructing printing of an output image.

[processing]
FIG. 11 is a flowchart showing the processing of the spectral color reproduction device 31.

  The control unit 11 displays the UI on the UI unit 28, and repeats the determination of whether or not the read button 707 has been pressed (S801) until the user presses the read button 707.

  When the read button 707 is pressed, the control unit 11 inputs a multiband image by the input unit 14 according to the path name input in the input image edit box 703, and stores it in the input image storage unit 16 (S802). In this case, the multiband image is not necessarily acquired by the input device 32, and can also be input from an external storage device or a server device on the network. Subsequently, the multiband image stored in the input image storage unit 16 is converted into a spectral reflectance by the spectral reflectance estimation unit 24, converted into the device RGB of the monitor 34 by the RGB calculation unit 27, and input by the UI unit 28. The image is displayed on the image display unit 701 (S803).

  Next, the control unit 11 inputs table data through the input unit 14 according to the path name input in the LUT edit box 704, and stores the table data in the LUT storage unit 18 (S804). Subsequently, the error calculation method corresponding to the selection of the error calculation method radio button 705 is read from the error calculation method storage unit 26 and set in the error calculation unit 25 (S805).

  Next, the control unit 11 determines the pressed button (S806), and if the user presses the read button 707, the process returns to step S802, and if the execute button 708 is pressed, the process returns to step S807. Proceed.

  When the execute button 708 is pressed, the control unit 11 converts the multiband image stored in the input image storage unit 16 into an output signal value and stores it in the output image storage unit 17 by the same processing as in the first embodiment. (S807). At that time, the error calculation unit 25 uses a set error calculation method.

  Next, the control unit 11 converts the output image stored in the output image storage unit 17 into a multiband image by the spectral reflectance estimation unit 24, converts it to device RGB by the RGB conversion unit 27, and outputs it by the UI unit 28. The image is displayed on the image display unit 702 (S808). Subsequently, the error calculated by the error calculation unit 25 is displayed on the error display unit 706 by the UI unit 28 (S809).

  Next, the control unit 11 determines the pressed button (S810) .If the user presses the read button 707, the process returns to step S802, and if the user presses the print button 709, the process returns to step S811. Proceed.

  When the print button 709 is pressed, the control unit 11 outputs the output image stored in the output image storage unit 17 by the output unit 15 to the output device 33 (S811).

  In this way, the user can specify a multiband image, table data, and an error calculation method using the UI, and convert the multiband image into an output image for the output device 33. Since an input image, an output image, and an error are displayed on the UI, the user can perform processing by confirming a visual and quantitative change in the output image by the calculation method.

[Other embodiments]
Note that the present invention can be applied to a system constituted by a plurality of devices (for example, a computer, an interface device, a reader, a printer, etc.), but an apparatus (for example, a copier, a facsimile machine, a control device) composed of a single device. Etc.).

  Another object of the present invention is to supply a storage medium storing a computer program for realizing the functions of the above-described embodiments to a system or apparatus, and the computer (CPU or MPU) of the system or apparatus executes the computer program. But it is achieved. In this case, the software read from the storage medium itself realizes the functions of the above embodiments, and the computer program and the computer-readable storage medium storing the computer program constitute the present invention. .

  Further, the above functions are not only realized by the execution of the computer program. That is, according to the instruction of the computer program, the operating system (OS) and / or the first, second, third,... This includes the case where the above function is realized.

  The computer program may be written in a memory of a device such as a function expansion card or unit connected to the computer. That is, it includes the case where the CPU of the first, second, third,... Device performs part or all of the actual processing according to the instructions of the computer program, thereby realizing the above functions.

  When the present invention is applied to the storage medium, the storage medium stores a computer program corresponding to or related to the flowchart described above.

Block diagram showing the configuration of a general colorimetric color reproduction system, Block diagram showing a spectral color reproduction system using a multiband input / output device, The figure explaining the space corresponding to a multiband pixel value, Block diagram showing a configuration example of the spectral color reproduction device of the embodiment, A flowchart showing processing of the spectral color reproduction device; A flowchart showing details of processing for calculating an output signal value; Flowchart showing details of inside / outside determination, A flowchart illustrating selection of an output signal value by the output signal selection unit; Block diagram showing a configuration example of the spectral color reproduction device of Example 2, The figure which shows an example of UI which a UI part displays on a display, It is a flowchart which shows the process of a spectral color reproduction apparatus.

Claims (7)

An input means for inputting a multiband image;
A memory that stores table data indicating a correspondence relationship between multiband pixel values and signal values output to an output device;
Means for constructing a table having a predetermined number of dimensions from the table data;
With reference to the table, determination means for determining whether or not the multiband pixel value of the input multiband image is within a region that can be reproduced by the output device;
When the result of the determination indicates the reproducible region, the calculation unit refers to the table and calculates a signal value to be output to the output device corresponding to the multiband pixel value;
The color processing apparatus according to claim 1, wherein, when the determination result indicates that the region is outside the reproducible region, the table is reconfigured by gradually reducing the number of dimensions of the table data.   2. The color processing apparatus according to claim 1, wherein the configuration unit performs table reconstruction by decreasing table data in order from a higher-order principal component of the table data.   3. The color processing apparatus according to claim 1, further comprising a selection unit that selects a signal value to be output to the output device when the calculation unit calculates a plurality of signal values. .   The selection unit converts the multiband pixel value into an input spectral reflectance, converts a multiband pixel value corresponding to each of the plurality of signal values into an output spectral reflectance, and outputs the input spectral reflectance and the output. 4. The color processing apparatus according to claim 3, wherein a signal value that minimizes a difference in spectral reflectance is selected. Enter a multiband image,
Configure a table with a predetermined number of dimensions from table data indicating the correspondence between multiband pixel values and signal values output to the output device,
With reference to the table, it is determined whether the multiband pixel value of the input multiband image is within a region that can be reproduced by the output device,
When the result of the determination indicates the reproducible region, the signal value output to the output device corresponding to the multiband pixel value is calculated with reference to the table,
A color processing method comprising: reconfiguring the table by gradually reducing the number of dimensions of the table data when the result of the determination indicates a region outside the reproducible region.   5. A computer program for controlling a computer device to function as each unit of the color processing device according to claim 1.   7. A computer-readable storage medium in which the computer program according to claim 6 is recorded.

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