JP2018105639A - Position detection device, electronic apparatus, and position detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position detection device, electronic apparatus, and position detection method capable of accurately detecting a position of a detection object in an image.SOLUTION: A position detection device includes: a distance calculation section for calculating a distance of a color coordinate at an object position in an object with respect to a color coordinate of a medium in a color space on the basis of a captured image obtained by imaging the media where the object is formed; and a position detection section for detecting a position of an object in the medium on the basis of a calculation result of the distance calculation section.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a position detection device, an electronic apparatus, and a position detection method.

  Conventionally, as an edge detection device that detects an edge of an image, an edge position is detected along one direction based on the target pixel of the image and two adjacent pixels adjacent to the target pixel along one direction. An apparatus is known (Patent Document 1).

  Specifically, in the apparatus described in Patent Document 1, after noise removal using a low-pass filter, the sum of two adjacent pixels (pixel values) and twice the target pixel (pixel value) Is obtained as a value indicating the edge size (edge size), that is, the sharpness of the edge, and a pixel of interest whose edge size exceeds a threshold value is detected as an edge. As a result, noise removal and effective edge dulling can be prevented, and the edge position can be detected with higher accuracy.

JP-A-8-315157

However, when the position of the detection target is detected by detecting the outer edge (edge) position of the detection target such as a color patch printed on a medium using the conventional apparatus described in Patent Document 1, It has been difficult to improve detection accuracy.
That is, when the pixel value of each pixel is determined by lightness (reflectance), it is difficult to detect edges having the same lightness and different colors. Specifically, it is difficult to detect the edge of a color patch with a low gradation value that has the same brightness as the media (boundary position with the media surface), so depending on the brightness and hue of the color patch, There was a problem that the position could not be detected with high accuracy.

  An object of the present invention is to provide a position detection device, an electronic device, and a position detection method that can detect the position of a detection target in an image with high accuracy.

  A position detection device according to an application example of the present invention is based on a captured image obtained by capturing an image of a medium on which an object is printed, and the color coordinate of the target position with respect to the color coordinate of the medium in a color space. A distance calculation unit that calculates a distance; and a position detection unit that detects a position of the object in the media based on the distance calculated by the distance calculation unit.

In this application example, the distance calculation unit calculates the distance of the color coordinate of the target position with respect to the color coordinate of the medium in the color space. The position detection unit detects the position of the object on the medium based on the calculated distance.
In such a configuration, the position of the edge of the object (boundary position with the media surface) can be detected with high accuracy, and consequently the position of the object on the media can be detected with high accuracy. For example, when a color patch printed on a medium is a detection target, the color patch and the medium are calculated by calculating the distance in the color space between the color coordinate at the target position on the color patch and the color coordinate of the medium. The position of the boundary with the surface can be detected with high accuracy, and as a result, the position of the color patch as the object in the captured image can be detected with high accuracy.

In the position detection device according to this application example, the distance calculation unit sets the color coordinates of the target position as ( _{RC1, RC2, RC3} ), and the media color coordinates as ( _{RM1, RM2, RM3} ). It is preferable to calculate R1 as the distance based on the following formula (1).

  In this application example, the distance in the color space is calculated by the above equation (1). Accordingly, the distance can be calculated for an arbitrary target position in the captured image using the pixel value of the target position. For example, when each pixel value in the captured image is acquired as a gradation value of each color of red (R), green (G), and blue (B), the above-mentioned distance in an arbitrary pixel is calculated using each pixel value. can do. Therefore, it is not necessary to perform processing such as conversion to a color space defined by other color coordinates, and the processing load can be reduced.

In the position detection apparatus of this application example, the distance calculation unit may calculate the target position when the color coordinates (R _M1, R _M2, R _M3 ) of the medium are R _M1 = R _M2 = R _M3 = R _W. It is preferable to calculate R1 as the distance based on the following equations (2) and (3), where the color coordinates are (R _C1, R _C2, R _C3 ), k _comp is a correction coefficient.

  In this application example, when adjusting the white balance of the captured image based on the color of the media, after performing grayscale conversion on the color coordinates of the target position based on the above equation (2), the above equation (3) is obtained. Based on this, the distance in the color coordinates of the target position after gray scale conversion is calculated. In such a configuration, the color coordinates of the target position can be compressed in the gray axis direction, and the influence of luminance unevenness due to the unevenness of the media can be suppressed. Further, since the same value can be used as each value of the color coordinate of the media, an increase in processing load when calculating the distance can be suppressed.

In the position detection device of the application example, it is preferable that the distance calculation unit sets a correction coefficient k _comp corresponding to the medium.
In this application example, by setting the correction coefficient k _comp according to the medium, for example, even if the color of the medium differs depending on the media type or the glossiness of the surface differs, an appropriate value as the correction coefficient k _comp Can be set. Accordingly, it is possible to suppress a decrease in the distance calculation accuracy due to the media type, and consequently to detect the position of the object with high accuracy.

In the position detection device according to this application example, the detection apparatus includes a detection range setting unit that sets a detection range for detecting an edge position of a color patch printed on the medium as the object, and the detection range setting unit includes a color of the medium. It is preferable that the detection range including is set, and the position detection unit detects the edge position in the detection range.
In this application example, the position detection unit sets the edge position of the color patch printed on the medium as a detection target, and the detection range setting unit sets a detection range including the color of the medium. In such a configuration, the detection range can be set so as to include the edge of the color patch to be detected. Therefore, the edge position can be detected more reliably, and the processing load can be reduced by narrowing the detection range.

In this application example, the detection range setting unit sets a determination range with respect to the target position in one direction, scans the target position and the determination range in the one direction, and the medium in the determination range Preferably, the target position when the color occupancy exceeds a predetermined value is set to the outer edge of the detection range.
In this application example, the detection range setting unit sets a determination range for determining whether to include the target position in the detection range with respect to the target position. Then, when the detection range setting unit scans the target position and the determination range in one direction, the detection position setting unit sets the target position when the amount of media color in the determination range exceeds a predetermined value as the outer edge of the detection range. To do. In such a configuration, the detection range can be narrowed down to a range including the vicinity region of the edge position, and the processing load due to the detection processing can be more reliably reduced.

  An electronic apparatus according to an application example of the invention is based on a captured image obtained by capturing an image of a medium on which an object is printed, and a color coordinate distance of the target position with respect to the color coordinate of the medium in a color space. A distance calculation unit that calculates the position, a position detection unit that detects the position of the object on the media based on the distance calculated by the distance calculation unit, and a process based on the detection result of the position of the object And a processing unit for performing the above.

  In this application example, as in the above application example, the distance at the target position of the captured image is calculated, and the position of the target object on the media is detected based on the calculated distance. Thereby, the position of the edge of the object (boundary position with the media surface) can be detected with high accuracy, and as a result, the position of the object on the medium can be detected with high accuracy.

  A position detection method according to an application example of the present invention includes position detection in a position detection device that detects the position of the object on the medium based on a captured image obtained by imaging the medium on which the object is printed. A method of calculating a distance of a color coordinate of a target position with respect to a color coordinate of the medium in a color space, and detecting a position of the target object on the medium based on the calculated distance And performing the above.

  In this application example, as in the above application example, the distance at the target position of the captured image is calculated, and the position of the target object on the media is detected based on the calculated distance. Thereby, the position of the edge of the object (boundary position with the media surface) can be detected with high accuracy, and as a result, the position of the object on the medium can be detected with high accuracy.

FIG. 2 is a diagram illustrating a configuration example of an appearance of the printer according to the first embodiment of the invention. 1 is a block diagram illustrating a schematic configuration of a printer according to a first embodiment. FIG. 2 is a schematic diagram illustrating a schematic configuration of an imaging unit in the printer of the first embodiment. The block diagram which shows the function structure of CPU with which the control unit of 1st Embodiment is provided. 6 is a flowchart illustrating an image processing method according to the first embodiment. The figure which shows typically the test pattern used for the image processing of 1st Embodiment. 5 is a flowchart illustrating a method for acquiring a color patch position according to the first embodiment. FIG. 3 is a diagram schematically illustrating a method for acquiring a color patch position according to the first embodiment. FIG. 3 is a diagram schematically illustrating a method for acquiring a color patch position according to the first embodiment. 5 is a flowchart illustrating a method for detecting an edge position according to the first embodiment. The figure which shows typically the detection method of the edge position of 1st Embodiment. The figure which shows typically the detection method of the edge position of 1st Embodiment. The figure which shows typically the detection method of the edge position of 1st Embodiment.

[First Embodiment]
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment according to the invention will be described with reference to the drawings. In the present embodiment, a printer 1 (inkjet printer) will be described as an example of a position detection apparatus and an electronic apparatus that perform the image processing method of the present invention.

[Schematic configuration of printer]
FIG. 1 is a diagram illustrating a configuration example of the appearance of the printer 1. FIG. 2 is a block diagram illustrating a schematic configuration of the printer 1.
As shown in FIG. 1, the printer 1 includes a supply unit 11, a transport unit 12, a carriage 13, a carriage moving unit 14, and a control unit 15 (see FIG. 2). The printer 1 controls the units 11, 12, and 14 and the carriage 13 based on print data input from an external device 20 such as a personal computer, and prints an image on the medium M. The printer 1 of the present embodiment forms a test pattern at a predetermined position on the medium M based on preset original image data, acquires a captured image of the test pattern, performs image processing, and is printed. Correction processing is performed when the captured image is not appropriate.
Hereinafter, each configuration of the printer 1 will be specifically described.

The supply unit 11 is a unit that supplies a medium M (an example of which is a paper surface in this embodiment) that is an image formation target to an image formation position. The supply unit 11 includes, for example, a roll body 111 (see FIG. 1) around which a medium M is wound, a roll drive motor (not shown), a roll drive wheel train (not shown), and the like. Then, based on a command from the control unit 15, the roll drive motor is rotationally driven, and the rotational force of the roll drive motor is transmitted to the roll body 111 via the roll drive wheel train. As a result, the roll body 111 rotates and the paper surface wound around the roll body 111 is supplied downstream (+ Y direction) in the Y direction (sub-scanning direction).
In the present embodiment, an example in which the paper surface wound around the roll body 111 is supplied is shown, but the present invention is not limited to this. For example, the medium M may be supplied by any supply method such as supplying the medium M such as a sheet of paper loaded on a tray or the like one by one with a roller or the like.

The transport unit 12 is the transport mechanism of the present invention, and transports the medium M supplied from the supply unit 11 along the Y direction, which is one direction of the present invention. The transport unit 12 includes a transport roller 121, a transport roller 121, a driven roller (not shown) that is driven by the transport roller 121, and a platen 122.
The conveyance roller 121 receives a driving force from a conveyance motor (not shown), and when the conveyance motor is driven by the control of the control unit 15, the conveyance roller 121 is rotationally driven by the rotation force, so that the medium M is placed between the conveyance roller 121 and the driven roller. It is transported along the Y direction while being sandwiched. A platen 122 facing the carriage 13 is provided on the downstream side (+ Y side) in the Y direction of the transport roller 121.

The carriage 13 includes a printing unit 16 that prints an image on the medium M, and an imaging unit 17 that performs imaging processing of a predetermined measurement position (measurement region) on the medium M.
The carriage 13 is provided by a carriage moving unit 14 so as to be movable along a main scanning direction (X direction) intersecting with the Y direction.
The carriage 13 is connected to the control unit 15 by a flexible circuit 131, and performs printing processing (image forming processing for the medium M) by the printing unit 16 and imaging processing by the imaging unit 17 based on a command from the control unit 15. carry out.
The detailed configuration of the carriage 13 will be described later.

The carriage moving unit 14 constitutes a moving mechanism that moves the carriage 13 and reciprocates the carriage 13 along the X direction based on a command from the control unit 15.
The carriage moving unit 14 includes, for example, a carriage guide shaft 141, a carriage motor 142, and a timing belt 143.
The carriage guide shaft 141 is disposed along the X direction, and both ends are fixed to, for example, a casing of the printer 1. The carriage motor 142 drives the timing belt 143. The timing belt 143 is supported substantially parallel to the carriage guide shaft 141, and a part of the carriage 13 is fixed. When the carriage motor 142 is driven based on a command from the control unit 15, the timing belt 143 travels forward and backward, and the carriage 13 fixed to the timing belt 143 is guided by the carriage guide shaft 141 and reciprocates.

Next, the configuration of the printing unit 16 and the imaging unit 17 provided on the carriage 13 will be described.
[Configuration of printing section]
The printing unit 16 forms an image on the medium M by ejecting ink onto the medium M individually at a portion facing the medium M.
The printing unit 16 is detachably mounted with ink cartridges (not shown) corresponding to a plurality of colors of ink, and ink is supplied from each ink cartridge to an ink tank (not shown) via a tube (not shown). Is done. Further, nozzles (not shown) for ejecting ink droplets are provided on the lower surface (position facing the medium M) of the printing unit 16 corresponding to each color. For example, piezo elements are arranged in these nozzles, and by driving the piezo elements, ink droplets supplied from the ink tank are ejected and land on the medium M to form dots.

[Configuration of imaging unit]
FIG. 3 is a diagram illustrating a schematic configuration of the imaging unit 17.
As illustrated in FIG. 3, the imaging unit 17 includes a light source 171, an imaging lens 172, and an imaging element 173. For example, in the carriage 13, the imaging unit 17 is disposed on the + X side and the + Y side of the printing unit 16. Has been.
Such an imaging unit 17 irradiates the medium M with illumination light from the light source 171 and causes the light reflected by the medium M to enter the imaging element 173 via the imaging lens 172. The image signal output from the image sensor 173 is input to the control unit 15 via an IV converter (not shown), an amplifier (not shown), and an AD converter (not shown).

The light source 171 causes the illumination light to enter the medium M at an incident angle of 45 ° ± 2 °. The light source 171 includes, for example, a light emitter such as a halongen lamp, an LED, or an LD, and an optical member such as a lens or an aperture that irradiates a predetermined area of the medium M with illumination light emitted from the light emitter. The
The imaging lens 172 includes a single lens or a plurality of lenses, and guides imaging light reflected in the normal direction at 0 ° ± 10 ° in the illumination area of the medium M to the imaging element 173.

  The imaging element 173 captures imaging light reflected by a predetermined imaging area on the medium M and guided to the imaging element 173 by the imaging lens 172. The image sensor 173 includes, for example, an RGB filter, and acquires a captured image by acquiring gradation value data of each color of R (red), G (green), and B (blue) in each pixel. In addition, the imaging element 173 acquires a captured image including a plurality of pixels arranged in one direction (horizontal direction) and a direction orthogonal to the one direction (vertical direction). As such an image sensor 173, various image sensors such as a CCD and a CMOS can be used.

[Control unit configuration]
Next, the control unit 15 will be described.
As shown in FIG. 2, the control unit 15 includes an I / F 151, a unit control circuit 152, a memory 153, and a CPU (Central Processing Unit) 154.
The I / F 151 inputs print data input from the external device 20 to the CPU 154.
The unit control circuit 152 includes control circuits that respectively control the supply unit 11, the transport unit 12, the printing unit 16, the light source 171, the imaging unit 17, and the carriage movement unit 14, and based on a command signal from the CPU 154. Control the operation of each unit. The control circuit of each unit may be provided separately from the control unit 15 and connected to the control unit 15.

The memory 153 stores various programs and various data for controlling the operation of the printer 1.
Examples of the various data include original image data for printing a test pattern, print profile data storing the ejection amount of each ink for color data included as print data, and the like.

FIG. 4 is a block diagram illustrating a functional configuration of the CPU 154 included in the control unit 15 of the printer 1.
The CPU 154 reads and executes various programs stored in the memory 153, and as shown in FIG. 4, the scanning control unit 154A, the print control unit 154B, the imaging control unit 154C, the patch position acquisition unit 154D, the correction unit 154E, and the like. Function as.

  The scanning control unit 154A outputs a command signal for driving the supply unit 11, the transport unit 12, and the carriage moving unit 14 to the unit control circuit 152. As a result, the unit control circuit 152 drives the roll drive motor of the supply unit 11 to supply the medium M to the transport unit 12. Further, the unit control circuit 152 drives the transport motor of the transport unit 12 to transport the predetermined area of the medium M along the Y direction to a position facing the carriage 13 of the platen 122. Further, the unit control circuit 152 drives the carriage motor 142 of the carriage moving unit 14 to move the carriage 13 along the X direction.

  The print control unit 154B outputs a command signal for controlling the printing unit 16 to the unit control circuit 152 based on, for example, print data input from the external device 20. When a command signal is output from the print control unit 154B to the unit control circuit 152, the unit control circuit 152 outputs a print control signal to the printing unit 16, and drives the piezo element provided in the nozzle to the medium M. Eject ink. When printing is performed, the carriage 13 is moved along the X direction, and during the movement, a dot forming operation for forming dots by ejecting ink from the printing unit 16 and the medium M are transported in the Y direction. The conveying operation is alternately repeated, and an image composed of a plurality of dots is printed on the medium M.

  The imaging control unit 154C performs imaging processing. Specifically, the imaging control unit 154C controls the imaging unit 17 to drive the imaging element 173, and acquires an image signal (captured image) input from the imaging element 173.

The patch position acquisition unit 154D detects the edge position of the color patch constituting the test pattern based on a captured image obtained by capturing a test pattern for calibration described later, and acquires the position of the color patch based on the detection result. To do. Here, in the present embodiment, the test pattern is formed by printing on the medium M a group of color patches that are adjacently arranged and configured by a plurality of color patches. Based on the captured image, the patch position acquisition unit 154D determines the boundary position between the surface of the medium M on which the color patch is not printed (hereinafter also referred to as a media area) and the color patch group, that is, the color patch group (color patch group). ) Edge is detected.
The patch position acquisition unit 154D functions as a detection range setting unit 154D1, a distance calculation unit 154D2, an edge detection unit 154D3, and a position calculation unit 154D4.

The detection range setting unit 154D1 sets a detection range when detecting the edge position in the captured image.
The distance calculation unit 154D2 calculates the distance in the color space of the color coordinate of each pixel in the detection range with respect to the color coordinate of the media surface. Here, the distance in the color space is a gradation value of each pixel with reference to the color coordinates on the surface of the medium. When the RGB color space is used as the color space, the R, G, and B gradation values that are image data of the captured image can be used as color coordinates. In addition to the RGB color space, a color space represented by another color coordinate system such as an XYZ color space can also be used. In this case, the distance calculation unit 154D2 calculates the distance in the XYZ color space using image data obtained by converting the R, G, and B tone values in each pixel into the XYZ coordinate system.

The edge detection unit 154D3 corresponds to a position detection unit, and detects the edge of the color patch group based on the distance in the color space calculated by the distance calculation unit 154D2.
The position calculation unit 154D4 calculates the position of the color patch group in the captured image and the position of the color patch constituting the color patch group based on the detection result of the edge of the color patch group by the edge detection unit 154D3.

  The correction unit 154E corresponds to a processing unit, and corrects (updates) the print profile data based on the captured image subjected to image processing, that is, the demosaic data in which the gradation value of each color is calculated for each pixel.

[Image processing method]
Next, an image processing method in the printer 1 of the present embodiment will be described based on the drawings.
FIG. 5 is a flowchart illustrating an image processing method in the printer 1. FIG. 6 is a diagram schematically illustrating an example of a color patch that is an edge position detection target in the printer 1.
The printer 1 prints a color patch group 30 (see FIG. 6) including a plurality of color patches 31 on the medium M, and detects the position of each printed color patch 31. The printer 1 performs various processes based on the captured image of the color patch 31.

As illustrated in FIG. 5, when the printer 1 receives a command to execute the spectroscopic measurement process, for example, by a user operation or an input from the external device 20, the scanning control unit 154 </ b> A and the print control unit 154 </ b> B The test pattern is printed (step S1).
That is, the scanning control unit 154A controls the supply unit 11 and the transport unit 12 to transport the medium M to a predetermined position of the platen 122, and the print control unit 154B controls the printing unit 16 to transport the transported media. Test pattern 3 (see FIG. 6) is printed at a predetermined position of M. The test pattern 3 is printed based on original image data stored in the memory 153 in advance. Accordingly, the scanning control unit 154A controls the transport amount of the medium M and the movement amount of the carriage 13 according to the original image data, and the print control unit 154B detects when the carriage 13 is positioned at a predetermined position based on the original image data. A test pattern 3 is formed by ejecting ink of a predetermined color. Further, if necessary, the ink may be dried by a drying mechanism.

  As shown in FIG. 6, the test pattern 3 includes a plurality of color patch groups 30 arranged along the main scanning direction (X direction) and the sub scanning direction (Y direction). The color patch group 30 includes a plurality of color patches 31 arranged adjacent to each other along the main scanning direction and the sub-scanning direction. The plurality of color patch groups 30 are spaced apart from each other. That is, the color patch 31 is not printed between the adjacent color patch groups 30 along the main scanning direction (X direction) and the sub-scanning direction (Y direction), and the media area where the surface of the medium M is exposed. Is formed.

  After the test pattern 3 is printed in step S1, the imaging control unit 154C controls the imaging unit 17 to acquire a captured image for the test pattern 3 (step S2). Specifically, the scanning control unit 154A controls the transport unit 12 and the carriage movement unit 14 to adjust the positions of the carriage 13 and the medium M so that the imaging unit 17 faces the test pattern. Then, the imaging control unit 154C turns on the light source 171 and drives the imaging element 173 to acquire an image signal (captured image) output from the imaging element 173.

Thereafter, the patch position acquisition unit 154D acquires the positions of the color patches 31 constituting the color patch group 30 based on the captured image (step S3). Details of step S3 will be described later.
After step S3, the correction unit 154E performs image analysis processing based on the R, G, and B gradation values in the captured image. Then, for example, a shading unevenness or white stripe based on the gradation value of the color patch 31 is detected, and a correction process for correcting the printing density of the nozzles of the printing unit 16 is performed (step S4).

[How to get color patch position]
FIG. 7 is a flowchart showing a method of acquiring a color patch position by the patch position acquisition unit 154D in step S3 of FIG. 8 and 9 are diagrams schematically illustrating an example of a procedure for acquiring a color patch position.
The patch position acquisition unit 154D detects the edge of the color patch group 30 in the captured image at a plurality of points, and calculates the position of the color patch 31 based on the detection result of the edge position.
Here, in the following description, the horizontal direction (left-right direction in FIG. 8) in the captured image is a direction along the main scanning direction (X direction) of the printer 1. Further, the vertical direction (up and down direction in FIG. 8) in the captured image is a direction along the sub-scanning direction (Y direction) of the printer 1. That is, the left and right edges of the color patch group 30 extend in the up-down direction, and the upper and lower edges extend in the left-right direction. Note that the horizontal direction (left-right direction) in the captured image and the main scanning direction in the printer 1 do not necessarily match due to the positional deviation of the medium M during conveyance. The same applies to the vertical direction (vertical direction) and the sub-scanning direction.

As illustrated in FIG. 7, the patch position acquisition unit 154D performs edge detection along the horizontal direction based on the captured image, and detects the left and right edge positions of the color patch group 30. Is performed (step S11).
In the edge detection process, the patch position acquisition unit 154D sets a detection range along the detection direction, and detects a boundary position between the color patch group 30 and the medium M in the set detection range as an edge position. In step S11, as shown in the upper diagram of FIG. 8, the patch position acquisition unit 154D sets the detection range Ar (first pre-detection range Ar1) so as to straddle the left boundary B3 of the color patch group 30 in the left-right direction. The left edge position (first pre-detection position Po1) is detected. Similarly, the patch position acquisition unit 154D sets a detection range Ar (second pre-detection range Ar2) including the right boundary B4 of the color patch group 30, and sets the right edge position (second pre-detection position Po2). Is detected.
Note that a detection range Ar setting method and an edge detection method will be described later.

Next, the patch position acquisition unit 154D performs edge detection along the vertical direction based on the detection result of the pre-detection process in step S11, and detects the upper and lower edge positions of the color patch group 30. A detection process is performed (step S12).
As shown in the middle diagram of FIG. 8, the patch position acquisition unit 154D sets the detection range Ar (first upper detection range Ar11) so as to straddle the upper boundary B1 of the color patch group 30 in the upper and lower directions. The first upper edge position P11 is detected as the edge position. Similarly, the patch position acquisition unit 154D sets the second upper detection range Ar12 and detects the second upper edge position P12. The first upper detection range Ar11 and the second upper detection range Ar12 are set between the first pre-detection position Po1 and the second pre-detection position Po2 in the left-right direction. Further, the second upper detection range Ar12 is set on the right side of the first upper detection range Ar11.
Similarly, the patch position acquisition unit 154D sets the first lower detection range Ar21 including the lower boundary B2, and detects the first lower edge position P21 as the lower edge position. Further, the patch position acquisition unit 154D sets the second lower detection range Ar22 including the boundary B2, and detects the second lower edge position P22.

Next, the patch position acquisition unit 154D performs edge detection along the horizontal direction based on the detection result of the upper and lower edge positions in step S12, and detects the left and right edge positions of the color patch group 30. A detection process is performed (step S13).
As shown in the lower diagram of FIG. 8, the patch position acquisition unit 154D sets the detection range Ar (first left detection range Ar31) so as to straddle the left boundary B3 of the color patch group 30; The first left edge position P31 is detected as the left edge position. Similarly, the patch position acquisition unit 154D sets the second left detection range Ar32 and detects the second left edge position P32. The first left detection range Ar31 and the second left detection range Ar32 are, in the vertical direction, a first upper edge position P11 and a second upper edge position P12, and a first lower edge position P21 and a second lower edge position P22. And set between.
Similarly, the patch position acquisition unit 154D sets the first right part detection range Ar41 including the right boundary B2, and detects the first right part edge position P41. Further, the patch position acquisition unit 154D sets the second right part detection range Ar42 including the boundary B2 and detects the second right part edge position P42.

Next, the position calculation unit 154D4 of the patch position acquisition unit 154D calculates the positions of the color patch group 30 and the color patch 31 based on the detection results of the edge positions in Step S12 and Step S13 (Step S14).
The position calculation unit 154D4 calculates the position of the color patch group 30 by calculating the coordinates of the points P5 to P8 at the four corners of the color patch group 30, as shown in FIG. Specifically, the position calculation unit 154D4 includes a first straight line L1 that passes through the first upper edge position P11 and the second upper edge position P12, and a second straight line that passes through the first lower edge position P21 and the second lower edge position P22. L2, a third straight line L3 passing through the first left edge position P31 and the second left edge position P32, and a fourth straight line L4 passing through the first right edge position P41 and the second right edge position P42. calculate. And position calculation part 154D4 calculates the coordinate of point P5 as an intersection of the 1st straight line L1 and the 3rd straight line L3. Similarly, the position calculation unit 154D4 calculates the point P6 from the first straight line L1 and the fourth straight line L4, the point P7 from the second straight line L2 and the third straight line L3, and the point P8 from the second straight line L2 and the fourth straight line L4. Calculate each coordinate.

  Further, the position calculation unit 154D4 calculates the position of each color patch 31 constituting the color patch group 30 from the coordinates of the points P5 to P8 at the four corners of the color patch group 30. For example, when the color patch 31 is formed with a predetermined width, the position calculation unit 154D4 can calculate the coordinates of the four corners and the coordinates of the center position of each color patch 31 based on the width of the color patch 31. .

[Edge position detection method]
Next, details of the edge position detection method in steps S11 to S13 will be described with reference to the drawings.
FIG. 10 is a flowchart illustrating an edge position detection method in the printer 1. FIGS. 11 to 13 are diagrams for explaining the edge position detection method shown in FIG.
In the following description, the case where edge detection is performed along the horizontal direction (left-right direction) and the edge position corresponding to the left boundary B3 is detected in step S11 and step S13 will be mainly described.

As illustrated in FIG. 10, the detection range setting unit 154D1 sets the detection range Ar along the detection direction of the edge position (step S21).
For example, as illustrated in the upper diagram of FIG. 11, the detection range setting unit 154D1 detects the edge position corresponding to the left boundary B3 of the color patch group 30 in the detection range Ar (first 1 pre-detection range Ar1, first left detection range Ar31, and second left detection range Ar32).
When detecting upper and lower edges along the vertical direction, the detection direction α is a direction from top to bottom in FIG.

As shown in FIG. 11, the detection range Ar is set so as to include the media area and straddle the boundary B3 of the color patch group 30A along the detection direction α. The size of the detection range Ar in the orthogonal direction β orthogonal to the detection direction α is smaller than that of the color patch 31. Thereby, the detection range Ar can be set so that the plurality of color patches 31 are not included.
In addition, the size of the detection range Ar in the detection direction α is larger than the size of the color patch 31. As a result, it is possible to suppress the occurrence of a problem that the detection range does not include the boundary B3 of the color patch group 30 and the edge position cannot be detected. In the present embodiment, the detection range Ar is set across the two color patch groups 30 along the detection direction α. The detection range Ar is set across two color patches 31A and 31B adjacent in the detection direction α in the color patch group 30A to be detected.

  The position of the detection range Ar is set based on, for example, the position of the boundary of the color patch group 30 or the position of the edge of the color patch 31 estimated by performing binarization processing on the captured image. Can do. That is, the detection range setting unit 154D1 estimates the position of the boundary of the color patch group 30A based on the result of the binarization process, and determines the position and size of the detection range Ar in the detection direction α so as to include the boundary. Can be set. For example, when the edge of the color patch 31A can be estimated, the detection range setting unit 154D1 detects in the orthogonal direction β so that the detection range Ar is located between the upper and lower edges of the color patch 31A. The position and size of the range Ar are set. If the lower edge of the color patch 31A cannot be detected, the first pre-process in the orthogonal direction β is similarly determined based on the estimation result of the left and right boundaries of the color patch group 30 and the width dimension of the color patch 31. The position of the detection range Ar1 is set. The width dimension of the color patch 31 can be estimated based on the estimated position of the left boundary of the color patch group 30A and the estimated position of the right boundary B4 of the color patch group 30B.

Next, the distance calculation unit 154D2 calculates the distance of the color coordinate of each pixel in the detection range Ar with respect to the color coordinate of the surface of the medium M in the color space (step S22).
In step S22, the color coordinates of each pixel in the detection range Ar and _{(R C1, R C2, R} C3), the color coordinates of the media M as the _{(R M1, R M2, R} M3), the distance calculation unit 154D2 is The distance of the color coordinate of each pixel with respect to the color coordinate of the medium M in the RGB color space is calculated based on the following formula (4), and is set as the gradation value R1 of each pixel. The gradation value R1 is a value obtained by performing gray scale conversion on the gradation value of each pixel based on the color coordinates of the medium M. For example, R _C1 corresponds to the R gradation value, R _C2 corresponds to the G gradation value, and R _C3 corresponds to the B gradation value.

Here, when the shading correction is performed on the captured image so that the gradation value of the medium M is uniform, the same value can be used as the color coordinate of the medium M for all the pixels. . Even when the shading correction is not performed, for example, the average value of each gradation value R _C1, R _C2, R _C3 of the medium M in the detection range Ar may be used.
When white balance adjustment is performed based on the color of the medium M, the same value can be used for each value of ( _{RM1, RM2, RM3} ).

Next, the edge detection unit 154D3 performs pixel averaging of the gradation value R1 of each pixel along the orthogonal direction β in the detection range Ar, and makes the gradation value R1 one-dimensional along the detection direction α (step) S23).
That is, the edge detection unit 154D3 calculates the average value R2 of the gradation values R1 of each pixel overlapping in the orthogonal direction β (see the lower diagram in FIG. 11). As a result, the detection range Ar is made one-dimensional in the detection direction α. By calculating the pixel average in the orthogonal direction β by the one-dimensional processing in step S23, the influence of the color unevenness of the color patch 31 is suppressed.

Next, based on the average value R2 calculated in step S23, the detection range setting unit 154D1 performs a process of narrowing down the detection range Ar so that the vicinity region of the detection target boundary is set as the detection range (step S24). .
As shown in FIG. 11, the detection range setting unit 154D1 detects a position where the average value R2 increases along the detection direction α (a position corresponding to the boundary B3) as an edge position, that is, detects a rising edge. The determination range Ard is set on the −α side of the determination position α _k (pixel position coordinates in the α direction) of the detection range Ar. Then, the detection range setting unit 154D1 along the detection direction alpha, scans the determined position alpha _k and the determination range Ard, determining position when occupancy of the media area in the determination range Ard exceeds a predetermined threshold value alpha _k Is set to the end point (corresponding to the outer edge) of the detection range.

Specifically, the detection range setting unit 154D1 sets the average value R2 in the detection range Ar using the binarization threshold R _th (see the upper diagram of FIG. 12) as shown in the following formula (5). Then, an inversion binarization process is performed, and a binarization process value R3 (α _k ) is calculated (see the middle diagram of FIG. 12). The binarization threshold R _th is set to a value smaller than the gradation value of each color patch 31 constituting the outer peripheral edge of the color patch 31 that is an edge detection target, that is, the color patch group 30.

Next, the detection range setting unit 154D1 sets a determination range Ard for each pixel position α _k of the detection range Ar, and calculates an integrated value V (α _k ) of R3 (α _k ) in the determination range Ard. To do. The integrated value V (α _k ) corresponds to the color occupation amount of the medium M in the determination range Ard.
When a rising edge is detected along the detection direction α, that is, when an upper edge or a left edge is detected, the determination range Ard is (α−Δα1) to (α -Δα2) (where Δα1> Δα2). Further, when detecting a rising edge, the integrated value V (α _k ) is calculated based on the following formula (6).

In addition, the detection range setting unit 154D1 determines, based on the following equation (7), all pixels in which the integrated value V (α _k ) is greater than the determination threshold V _th for each pixel position α _{k in} the detection range Ar. A narrow-down function F (α _k ) for calculating the range including the position α _k as the detection range Ar is calculated.
In the example shown in the middle view of FIG. 12, in a range from the pixel position alpha ₁ pixel position alpha _2, the value of the integrated value V (alpha _k) is greater than the determination threshold V _th. That is, the value of the narrowing-down function F (α _k ) is _{1 in} the range from the pixel position α ₁ to the pixel position α ₂ as shown in the lower diagram of FIG. 12, and is 0 in the other ranges. Note that a range indicated by a ray in the middle diagram of FIG. 12 corresponds to a detection region where the medium M is detected.

As described above, in the present embodiment, when detecting the rising edge, the determination range Ard, is set to -α side pixel position alpha _k. As a result, the detection range Ar is narrowed down so as to include the position corresponding to the rising edge of the binarization processing value R3 (α _k ) and not include the position corresponding to the falling position (corresponding to the falling edge). it can. Accordingly, it is possible to suppress erroneous detection of the falling edge corresponding to the edge of the other color patch group 30 adjacent to the detection target color patch group 30 (corresponding to the boundary B4 in the upper diagram of FIG. 12).

On the other hand, when detecting the falling edge along the detection direction alpha, that is, when detecting the lower edge and the right edge, the determination range Ard is set in the range of (α _{k +} Δα2) of (α _{k +} Δα1) The That is, the determination range Ard is set on the + α side of the pixel position α _k . Accordingly, it is possible to suppress erroneous detection of a rising edge (corresponding to the boundary B3 in the upper diagram of FIG. 12) in another color patch group 30 adjacent to the color patch group 30 to be detected.
Further, the integrated value V (α) when detecting the falling edge is calculated based on the following equation (8).

Here, Δα1, Δα2, and _Vth are set so that the detection range can be narrowed down to a range including only the detection target edge. Specifically, Δα1 is obtained through experiments, simulations, or the like in advance according to the tone values of the color patches 31 and the media M and the characteristics of the imaging unit 17 (for example, the light amount of the light source 171 and the sensitivity of the imaging element 173). , it can be calculated Derutaarufa2, and _{V t} h.

  For example, Δα1 is preferably set to be smaller than at least the width dimension of the color patch 31 in the α direction. Thereby, it is possible to suppress the detection range in which the range is narrowed down from including two or more color patches 31, and it is possible to suppress the detection of the edge of the color patch 31 other than the edge of the color patch group 30.

Further, it is possible by providing the Derutaarufa2, pixel position alpha _k outside the determination range Ard sets the determination range Ard so as to be located. Therefore, the detection range can be narrowed down so that the detection target edge (corresponding to the boundary B3 in the upper diagram of FIG. 12) is included in the detection range after narrowing down more reliably. Note that, by reducing Δα2, the end point of the narrowing range can be brought close to the detection target edge (corresponding to the boundary B3 in the upper diagram of FIG. 12). However, when the captured image has a low image quality, There is also a possibility that a problem that the detection target edge is not included in the detection range may occur. That is, by reducing Δα2 within a range in which the above-described problem does not occur, the target range for specifying the edge position described later can be reduced, and the processing load can be reduced.

Further, by increasing the V _th, although it is possible to increase the narrowing amount is too large V _th, likewise, a problem that does not include the detection target of edge detection range after narrowing occurs There is a fear. Therefore, by increasing _Vth within a range where the above-described problem does not occur, the target range when specifying the edge position described later can be reduced, and the processing load can be reduced.

Returning to FIG. 10, the edge detection unit 154D3 performs spatial differentiation on the average value R2 in the detection range Ar by using a differential filter whose filter coefficient is [-1, 0, 1] from the -α side. A differential value ΔR2 (α _k ) is acquired (step S25).
As shown in the upper diagram of FIG. 13, the differential value ΔR2 (α _k ) is a positive value along the detection direction α at a position where the average value R2 corresponds to the rising edge, and a position corresponding to the falling edge. In, the value is negative, and in other positions, the value is near zero.
Note that a filter that outputs the differential value in the detection range subjected to the narrowing process in step S24 and outputs 0 in other areas may be used. Thereby, an increase in processing load in the spatial differentiation process can be suppressed.

Next, the edge detection unit 154D3 specifies the edge position based on the result of narrowing down the detection range (detection range) in step S24 and the result of the spatial differentiation acquired in step S25 (step S26).
Specifically, the edge detection unit 154D3 applies the narrowing function F (α _k ) to the differential value ΔR2 (α _k ) as shown in the lower diagram of FIG. 13, that is, the narrowing function F (α _k ). The edge position is specified based on the value of the product of the differential value ΔR2 (α _k ). FIG. 13 illustrates the case where the left edge is detected, and the rising edge corresponding to the boundary B3 of the color patch group 30 to be detected is detected.

In this embodiment, in step S24, the detection range is narrowed down so that the detection range includes only the edge to be detected. Therefore, as illustrated in FIG. 13, when detecting the rising edge, the edge detection unit 154D3 sets the position where F (α _k ) · ΔR2 (α _k ) is the maximum value as the edge position. Further, when detecting a falling edge, a position where F (α _k ) · ΔR 2 (α _k ) is the minimum value is set as the edge position.

Note that the edge detection unit 154D3 detects a rising edge, and when there are a plurality of edge candidate positions where F (α _k ) · ΔR2 (α _k ) is the maximum value, the edge detection unit 154D3 is the closest to the -α side. Let the position be the edge position.
Further, the edge detection unit 154D3 detects a falling edge, and when there are a plurality of edge candidate positions where F (α _k ) · ΔR2 (α _k ) is the minimum value, Let the position be the edge position.

Next, the edge detection unit 154D3 determines whether or not all edge positions have been detected for the detection target edge of the color patch group 30A (see FIG. 11) (step S27).
For example, in the pre-detection process of the left and right edge positions in step S11, when the edge detection unit 154D3 detects the edge position of each of the left rising edge and the right falling edge, YES is determined. Determination is made, and the process according to the flowchart shown in FIG. 10 is terminated. On the other hand, when all edge positions are not detected, the edge detection unit 154D3 returns to step S21 and detects an undetected edge position.

In the detection process of the upper and lower edge positions in step S12, when the edge detection unit 154D3 detects two edge positions for each of the upper rising edge and the lower falling edge, YES in step S27. Is determined.
In the detection processing of the left and right edge positions in step S13, if the edge detection unit 154D3 has detected two edge positions for each of the left rising edge and the right falling edge, YES in step S27. Is determined.

[Effects of First Embodiment]
In the present embodiment, the distance calculation unit 154D2 calculates the distance between the color coordinates of the target position of the color patch group 30 as the target with respect to the color coordinates of the medium M in the RGB color space. The edge detection unit 154D3 detects the edge position of the color patch group 30 on the medium M based on the calculated distance. With such a configuration, the edge position can be detected with high accuracy, and consequently the positions of the color patch group 30 and the color patch 31 on the medium M can be detected with high accuracy. That is, in the present embodiment, when the color patch group 30 and the color patch 31 printed on the medium M are to be detected, the color patch 31 and the color patch 31 are calculated by calculating the distance between the color coordinates of the target position in the color space described above. The boundary position with the surface of the medium M can be detected with high accuracy. Therefore, the position of the color patch 31 in the captured image can be detected with high accuracy.

  In the present embodiment, the distance calculation unit 154D2 calculates the distance in the color space by the above equation (4). Accordingly, the distance can be calculated for an arbitrary target position in the captured image using the pixel value of the target position. That is, when each pixel value in the captured image is acquired as a gradation value of each color of red (R), green (G), and blue (B) as in this application example, each pixel value is arbitrarily used. It is possible to calculate the distance in the pixel. Therefore, it is not necessary to perform processing such as conversion to a color space defined by other color coordinates, and the processing load can be reduced.

  In the present embodiment, the detection range setting unit 154D1 sets a detection range including the color of the medium M. In such a configuration, the detection range can be set so as to include the edge of the color patch group 30 (color patch 31) to be detected. Therefore, the edge position can be detected more reliably, and the processing load can be reduced by narrowing the detection range.

  In the present embodiment, the detection range setting unit 154D1 sets a determination range for each pixel position in the detection range Ar along the detection direction α, and the occupation amount of the medium M is a predetermined value (determination threshold Vth). A pixel position in which a determination range that exceeds is set as an end point of the detection range. As a result, the detection range Ar can be narrowed to include at least the region near the edge position, and the processing load due to the detection process can be reduced.

  In this embodiment, when a rising edge is detected, a determination range is set on the −α side in the detection direction α with respect to the pixel position to be determined. When detecting a falling edge, a determination range is set on the + α side in the detection direction α with respect to the pixel position to be determined. Thereby, the determination range can be set so as to include only the detection target edge, and the erroneous detection of the edge can be more reliably suppressed.

[Second Embodiment]
Hereinafter, a second embodiment will be described.
In the first embodiment, the patch position acquisition unit 154D calculates the distance of each pixel in the color space using the above equation (4). On the other hand, the second embodiment is different from the first embodiment in that the distance in the color space is calculated after performing grayscale conversion on the gradation value of each pixel.
In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

In the second embodiment, the distance calculation unit 154D2 performs grayscale conversion using, for example, the following equation (9) when calculating the distance in the color space in step S12.
Here, the gray scale conversion using the following formula (9) can be performed when white balance adjustment is performed based on the color of the medium M. Note that the following equation (9), the tone value R _M1 of each color of the medium M, the R _M2, R _M3 and the _{R w.} In addition, each value (coefficient) in the conversion matrix when performing grayscale conversion is not limited to the value shown in the following formula (9), and various values can be appropriately used for the conversion method.

In the color space defined by the converted color coordinates (R _gray , R _U , R _V ), the color coordinate value of each pixel is a value based on the color coordinate of the medium M. Therefore, the distance calculation unit 154D2 calculates the distance of the color coordinates (R _gray , R _U , R _V ) of each pixel with respect to the color coordinates of the medium M in the converted color space by the following equation (10). Can do.
In the following equation (10), k _comp is a correction coefficient on the gray axis, and is a value corresponding to the color of the medium M. For example, k _comp is acquired in advance through experiments or the like and stored in the memory 153. The distance calculation unit 154D2 acquires k _comp according to the type of the medium M. Note that the type of the medium M may be specified by the user, or may be determined based on the gradation value of the media area in the captured image.

[Effects of Second Embodiment]
In the present embodiment, when the white balance of the captured image is adjusted based on the color of the medium M, gray scale conversion is performed on the color coordinates of the target position based on the above equation (9). Further, the distance in the color coordinates of the target position after gray scale conversion is calculated based on the above equation (10). In such a configuration, the color coordinates of the target position can be compressed in the gray axis direction, and the influence of uneven brightness due to the unevenness of the medium M can be suppressed. Moreover, since the same value can be used as each value of the color coordinates of the medium M, an increase in processing load when calculating the distance can be suppressed.

Further, by setting the correction coefficient k _comp according to the media, for example, even when the color of the media differs depending on the media type or the gloss of the surface is different, an appropriate value is set as the correction coefficient k _comp. be able to. Accordingly, it is possible to suppress a decrease in the distance calculation accuracy due to the media type, and consequently to detect the position of the object with high accuracy.

[Modification]
Note that the present invention is not limited to the above-described embodiments, and the present invention includes configurations obtained by modifying, improving, and appropriately combining the embodiments as long as the object of the present invention can be achieved. Is.

In the above embodiments, the positions of the four corners of the color patch group 30 are calculated and the positions of the color patch group 30 and the color patch 31 are calculated. However, the present invention is not limited to this, and the position of at least one corner is determined. The positions of the color patch group 30 and the color patch 31 may be calculated. For example, one of the upper and lower edges and the left and right edges of the color patch group 30 are detected, and the coordinates of the intersection of these edges are calculated. Further, the type of the detected edge is specified according to the detection direction and whether or not the detected edge is a rising edge. For example, when edge detection is performed along the horizontal direction and a rising edge is detected, it can be specified that the detected edge is the left edge. Therefore, the position of each color patch can be calculated based on the type of edge, the coordinate position of the intersection, and the size of the color patch.
If only one of the top, bottom, left, and right edges is detected, edge detection may be performed along the detected edges to detect coordinates corresponding to the corners of the color patch group 30.

  In each of the above embodiments, the left and right edge positions are pre-detected and the top and bottom edge positions are detected based on the pre-detection result, but the present invention is not limited to this. For example, the pre-detection of the upper and lower edge positions may be performed, and the left and right edge positions may be detected based on the pre-detection result. Further, the left and right edge positions and the upper and lower edge positions may be detected without performing the pre-detection of the edge positions.

  In each of the embodiments described above, the detection of the left and right edge positions and the detection of the upper and lower edge positions are performed by detecting two edge positions for each edge, but the present invention is not limited to this. For example, only one edge position may be detected, or three or more points may be detected. When detecting a plurality of edge positions of three or more points, straight lines corresponding to the edges may be calculated based on the plurality of edge positions by the mean square method or the like.

  In each of the above-described embodiments, the pixel average of each pixel value is calculated along the orthogonal direction β as the one-dimensional processing, but is not limited to this. For example, a binarization process or the like may be performed on the captured image to estimate the edge extension direction, and the pixel average may be calculated along the estimated extension direction. Further, the direction orthogonal to the extending direction may be set as the detection direction α. As a result, even when there is a large shift between the horizontal direction of the captured image and the main scanning direction of the printer 1 due to misalignment or undulation of the medium M, a problem that the pixel average is calculated across the inside and outside of the color patch is suppressed. And the edge position detection accuracy can be improved.

In each of the above embodiments, the determination range Ard that does not include the determination position is set as the determination range Ard when the detection range Ar is narrowed down. However, the present invention is not limited to this, and the determination range Ard that includes the determination position is set. May be. For example, in the above embodiments, when a rising edge is detected in the detection direction α, the determination range Ard is set on the −α side of the determination position. On the other hand, for example, the determination range Ard including the determination position may be set as an end point on the + α side without setting Δα2. When a falling edge is detected, a determination range Ard including a determination position is set as an end point on the −α side.
That is, when edge detection is performed from the media area toward the color patch, a determination range may be set in an area including the determination position and an area downstream of the determination position in the detection direction. When edge detection is performed from the color patch area toward the media area, the determination range Ard may be set in an area including the determination position and an area upstream in the detection direction from the determination position. As a result, as in the above embodiments, edges that are not detection targets can be excluded from the detection range, and erroneous detection of edges can be suppressed.

  In each of the above embodiments, the detection range is narrowed down to limit one detection target edge as described above, but the present invention is not limited to this. For example, a plurality of edges may be detected along the detection direction. In this case, a determination range Ard including the determination position may be set. For example, the determination position may be located at the center of the determination range Ard. Thereby, the vicinity area | region of a some edge along a detection direction can be included in a detection range.

  Further, when a plurality of edges are detected along the detection direction, the positions of the color patch group 30 and the color patch 31 may be calculated according to the type of detected edge and the position of the detected edge. . For example, when a rising edge and a falling edge are detected in order along the detection direction, the range between these two edges is the formation range of the color patch group 30.

In each of the above embodiments, the detection range is set along the detection direction α and the orthogonal direction β. However, the present invention is not limited to this, and the detection range may be set only along the detection direction α. Thereby, the increase in the processing load of the edge detection process in each detection range can be suppressed.
In this case, by detecting a plurality of edge positions for each edge and calculating a straight line corresponding to the edge by the mean square method or the like based on the plurality of edge positions as described above, the edge detection accuracy is improved. Can be improved.

  In each of the embodiments described above, the case where a plurality of color patches detect the edge of a color patch group arranged adjacent to each other along the main scanning direction and the sub-scanning direction is exemplified, but the present invention is not limited to this. For example, a color patch group in which color patches are adjacently arranged along either the main scanning direction or the sub-scanning direction may be a detection target. A single color patch surrounded by the media area may be a detection target. Further, an object other than the color patch formed on the medium may be set as the detection target.

  In each of the above embodiments, the imaging unit 17 is mounted on the carriage 13 and configured to be movable in one direction with respect to the medium M. However, the present invention is not limited to this. For example, the imaging unit 17 may be configured not to be mounted on the carriage and may capture a predetermined imaging range, or may be configured to be movable by another moving mechanism separately from the carriage 13.

  In each of the above embodiments, the case where a captured image is acquired using the imaging unit 17 including the imaging element 173 and the pixel value of each pixel (respective gradation values of R, G, and B) is illustrated is exemplified. It is not limited to this. For example, the pixel value of each pixel may be acquired based on a spectral image acquired for a plurality of wavelengths using a spectral filter such as an interference filter.

  In each of the above embodiments, the printer 1 is exemplified as an electronic apparatus including the position detection device of the present invention, but the present invention is not limited to this. For example, the position detection device may use an object printed on the medium M by a printer separate from the position detection device as the position detection target.

  Moreover, although the structure which made the detection object the target object printed on the medium with the printer was illustrated, it is not limited to this. The position detection method according to the present invention can be particularly preferably used when detecting the position of an object to be imaged based on a captured image. For example, when inspecting a manufactured product in a production line such as a factory, The product may be imaged by an imaging device, and the position detection method of the present invention may be applied to the captured image. Furthermore, the present invention is not limited to the use such as the inspection as described above. For example, the present invention can be applied to a captured image captured by a digital camera or the like in a general household.

  In addition, the specific structure for carrying out the present invention may be configured by appropriately combining the above-described embodiments and modifications within the scope that can achieve the object of the present invention, and may be appropriately changed to other structures and the like. May be.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 30, 30A, 30B ... Color patch group, 31, 31A, 31B ... Color patch, 154D ... Patch position acquisition part, 154D1 ... Detection range setting part, 154D2 ... Distance calculation part, 154D3 ... Edge detection part, 154D4 ... position calculation unit, 154E ... correction unit, Ar ... detection range, Ar1 ... first pre-detection range, Ar11 ... first upper detection range, Ar12 ... second upper detection range, Ar2 ... second pre-detection range, Ar21 ... first 1 lower detection range, Ar22 2nd lower detection range, Ar31 1st left detection range, Ar32 2nd left detection range, Ar41 1st right detection range, Ar42 2nd right detection range, Ard ... judgment range, M ... media, P11 ... first upper edge position, P12 ... second upper edge position, P21 ... first lower edge position, P22 ... second lower edge Position, P31 ... first left edge position, P32 ... second left edge position, P41 ... first right edge position, P42 ... second right edge position, Po1 ... first pre-detection position, Po2 ... second Pre-detection position.

Claims (8)

A distance calculation unit that calculates a distance of a color coordinate of the target position with respect to a color coordinate of the medium in a color space, based on a captured image obtained by imaging the medium on which the object is printed;
A position detection unit configured to detect a position of the object on the medium based on the distance calculated by the distance calculation unit. The position detection device according to claim 1,
The distance calculation unit sets the color coordinates of the target position as ( _{RC1, RC2, RC3} ) and the media color coordinates as ( _{RM1, RM2, RM3} ), and is based on the following formula (1). R1 is calculated as the distance

A position detecting device characterized by that. The position detection device according to claim 1,
When the color coordinates (R _M1, R _M2, R _M3 ) of the media are R _M1 = R _M2 = R _M3 = R _W , the distance calculation unit calculates the color coordinates of the target position (R _C1, R _{C2 ,} R _C3 ), k _comp as a correction coefficient, and R1 is calculated as the distance based on the following equations (2) and (3).

A position detecting device characterized by that. In the position detection device according to claim 3,
The distance calculation unit sets a correction coefficient k _comp corresponding to the medium. In the position detection device according to any one of claims 1 to 4,
A detection range setting unit for setting a detection range for detecting an edge position of a color patch printed on the medium as the object;
The detection range setting unit sets the detection range including the color of the media,
The position detection device detects the edge position in the detection range. The position detection device according to claim 5,
The detection range setting unit
In one direction, set a determination range for the target position,
Scanning the target position and the determination range in the one direction, and setting the target position when the occupation amount of the color of the medium in the determination range exceeds a predetermined value as an outer edge of the detection range; A position detection device. A distance calculation unit that calculates a distance of a color coordinate of the target position with respect to a color coordinate of the medium in a color space, based on a captured image obtained by imaging the medium on which the object is printed;
A position detection unit that detects a position of the object in the media based on the distance calculated by the distance calculation unit;
An electronic device comprising: a processing unit that performs processing based on a detection result of the position of the object. A position detection method in a position detection device for detecting the position of the object on the medium based on a captured image obtained by imaging the medium on which the object is printed,
Calculating a distance of a color coordinate of a target position with respect to a color coordinate of the medium in a color space;
Detecting the position of the object on the medium based on the calculated distance. A position detection method comprising:

Images