JP7747404B2 - Image reading device, image reading control method and program - Google Patents

Description

The present invention relates to an image reading device, an image reading control method, and a program.

In image reading devices such as line cameras and line scanners that have lighting, lenses, and image sensors such as CCDs, uneven luminance values of pixels in the read image can occur due to uneven illuminance of the light source caused by differences in luminance between individual LED (Light Emitting Diode) elements. Figure 11(a) shows an example of such a read image. Shading correction is generally performed to eliminate uneven luminance values in the read image. Figure 11(b) shows an example of a read image after shading correction has been performed.

Image reading devices installed in typical multifunction devices have white and black references placed inside the housing, and shading correction data is reacquired each time a scan is performed, or when the power is turned on or at regular intervals. However, even when the same light source is used, the amount of illuminance unevenness varies depending on the reflectance of the object being scanned and the lighting arrangement, so shading correction data based on specific white and black references alone may not be sufficient to correct the unevenness. In response to this, for example, Patent Document 1 discloses a technology that performs shading correction that flexibly responds to variations in the diffusion characteristics of reflected light on the surface of the object being scanned.

In addition, when there are changes in reading conditions, such as a deterioration in the illuminance of the light source, changes in brightness settings and placement, or a change in the reading object, it is preferable to read the white and black references used for shading correction and re-acquire shading correction data. For example, on a production line that handles multiple types of reading objects, correction data must be acquired and changed each time the reading object changes. However, in image reading devices used for industrial purposes, the production line is always in operation, and there is often no opportunity to place the white and black references each time an image is read.

Japanese Patent Application Laid-Open No. 2021-103873

There is a need for a method to automatically generate and switch shading correction data without interrupting the image reading process to obtain the shading correction data.

The object of this invention is to provide an image reading device, an image reading control method, and a program that solve the above-mentioned problems.

According to one aspect of the present invention, an image reading device generates general-purpose shading correction data by reading an image using a white reference and a black reference in a state where all of a plurality of light sources are turned on, the image reading device including: a first acquisition means for acquiring a diffusion state of a first reflected light generated by irradiating light from a specific light source among the plurality of light sources in a state where the image reading is performed using the white reference and the black reference; a second acquisition means for acquiring a diffusion state of a second reflected light generated by irradiating light from the specific light source in a state where the image reading target is read; and a generation means for generating shading correction data for a reading target that depends on the reading target, based on the diffusion state of the first reflected light, the diffusion state of the second reflected light, and the general-purpose shading correction data. and a reading means for reading an image by irradiating light from all of the plurality of light sources and reading the image using shading correction data for the read object, wherein the second acquisition means cuts out a predetermined single light source acquisition area from an image of the read object, the single light source acquisition area including an area where the brightness of the reflected light generated by irradiation of light from the specific light source is maximum, and acquires the diffusion state of the second reflected light in the cut-out single light source acquisition area, and the reading means cuts out, from the image of the read object, the remaining area after cutting out the single light source acquisition area or an area that includes part of the single light source acquisition area, as an image reading area, and performs shading correction on the cut-out image reading area using the shading correction data for the read object.

According to one aspect of the present invention, an image reading control method includes a step of generating general-purpose shading correction data by reading an image using a white reference and a black reference with all of a plurality of light sources turned on; a step of acquiring a diffusion state of a first reflected light generated by irradiating light from a specific light source among the plurality of light sources when reading the image using the white reference and the black reference; a step of acquiring a diffusion state of a second reflected light generated by irradiating light from the specific light source when reading an image reading target; a step of generating shading correction data for a reading target that depends on the reading target based on the diffusion state of the first reflected light, the diffusion state of the second reflected light, and the general-purpose shading correction data; and a step of acquiring a diffusion state of a second reflected light generated by irradiating light from the specific light source when reading the image reading target. In the state of executing the method, the method includes a step of performing image reading using shading correction data for the read object while irradiating light from all of the plurality of light sources, wherein in the step of acquiring the diffusion state of the second reflected light, a predetermined single light source acquisition area including an area where the brightness of the reflected light generated by irradiating light from the specific light source is maximum is cut out from the image of the read object, and the diffusion state of the second reflected light in the cut-out single light source acquisition area is acquired, and in the step of performing image reading, either the remaining area cut out from the image of the read object after the single light source acquisition area has been cut out, or an area which partially includes the single light source acquisition area, is cut out as an image reading area, and shading correction is performed on the cut-out image reading area using the shading correction data for the read object.

According to one aspect of the present invention, a program causes a computer to execute the image reading control method described above .

This invention allows shading correction data to be generated automatically without interrupting the image reading process for the target image.

FIG. 1 is a diagram illustrating an example of an image scanner including an image reading device according to an embodiment. FIG. 1 is a diagram illustrating an example of a structure of an image reading apparatus according to an embodiment. FIG. 2 is a block diagram illustrating an example of functions of the image reading apparatus according to the embodiment. 1A and 1B are diagrams illustrating an example of the structure of a light source module according to an embodiment. FIG. 10 is a diagram showing an example of a reference single light source lighting pattern according to the embodiment. 10A and 10B are diagrams illustrating an example of a lighting pattern of a single light source for a reading object according to the embodiment. FIG. 10 is a diagram showing an example of general-purpose shading correction data according to the embodiment. FIG. 10 is a diagram showing an example of shading correction data for a reading object according to the embodiment. 10 is a flowchart illustrating an example of a preparation process according to the embodiment. 10 is a flowchart illustrating an example of a process for generating shading correction data according to the embodiment. FIG. 10 is a diagram illustrating shading correction. FIG. 1 is a block diagram showing the configuration of an image reading apparatus having a minimum configuration. FIG. 10 is a flowchart showing the operation of an image reading apparatus having a minimum configuration.

The image reading device according to each embodiment of the present invention will be described below with reference to the drawings. In the drawings used in the following description, parts not related to the present invention will be omitted from the description and may not be shown.

<Embodiment>
(composition)
FIG. 1 is a diagram showing an example of an image scanner including an image reading device according to an embodiment.
1, the image scanner 1 includes an image reading device 10, a read object 20, and a read object transport system 30. The image reading device 10 photographs the read object 20, which is transported by the read object transport system 30, from above, and outputs a read image of the read object 20. The read object 20 may be, for example, various types of paper, cloth, metal plate, etc.

FIG. 2 is a diagram illustrating an example of the structure of the image reading apparatus according to the embodiment.
Fig. 2(a) shows a side view of the image scanner 1 including an image reading device, and Fig. 2(b) shows a front view of the image scanner 1 including an image reading device. In the following explanation, for convenience of explanation, the XYZ coordinate space will be appropriately shown in the drawings. Fig. 2(a) is a YZ plane view of the image scanner 1 as seen in the positive direction of the X axis, and Fig. 2(b) is an XZ plane view of the image scanner 1 as seen in the positive direction of the Y axis.

The image reading device 10 includes a control board 100, a light source module 11 such as an LED, a CCD (Charge-Coupled Device) 12, a lens 13, two mirrors 14, and a cover glass 15. Note that the light source module 11 may be installed external to the image reading device 10.

The control board 100 has the function of controlling the overall operation of the image reading device 10, and controls the light source module 11 and CCD 12. Details of the control board 100 will be described later with reference to Figure 3.

As shown in FIG. 2, the main optical components, such as the light source module 11, CCD 12, lens 13, mirror 14, and cover glass 15, are arranged and fixed in the main structural zone within the image reading device 10, forming a reading light path. When the light source module 11 irradiates the reading target 20 with light, the reflected light generated on the surface of the reading target 20 passes through the cover glass 15 and then enters the lens 13 via the two mirrors 14, and is then imaged by the lens 13 on the CCD 12. Note that the image reading device 10 may not include the mirror 14; in this case, the reflected light passes through the cover glass 15 and then enters the lens 13.

The light source module 11, CCD 12, lens 13, mirror 14, cover glass 15, and the reflected light reading optical path formed by these components have depth in the X-axis direction. The CCD 12 is a line image sensor or area image sensor, and captures reflected light at each X coordinate value in the X-axis direction or each XY coordinate value on the XY plane. The CCD 12 outputs an analog signal representing the input reflected light to the control board 100 as image data 200 for each X coordinate value or XY coordinate value. As described below, in this embodiment, a single light source acquisition area 201 and an image reading area 202 are extracted from the image data 200 output by the CCD 12, shading correction data is generated using the single light source acquisition area 201, and shading correction is performed on the image reading area 202.

The image scanner 1 has a shading correction function that uses a white reference and a black reference, and for example, has a built-in white reference board and a built-in black reference board (not shown). The image reading device 10 uses this shading correction function to generate general-purpose shading correction data 153. The general-purpose shading correction data 153 is shading correction data generated by a general image reading device. The image reading device 10 stores the generated general-purpose shading correction data 153 in the memory area 150.

FIG. 3 is a block diagram illustrating an example of functions of the image reading apparatus according to the embodiment.
3 , the control board 100 is connected to the light source module 11 and the CCD 12. The control board 100 includes a light source control circuit 110, an AFE (Analog Front End) 120, an image control circuit 130, an external I/F 140, and a storage area 150.

The light source control circuit 110 controls the light source module 11 to control the brightness and lighting pattern of the light source. Figure 4(a) shows an example of the structure of the light source module 11 according to this embodiment. The light source module 11 includes an LED board 111, multiple LED elements 112, a diffuser 113, and an LED lighting housing 114. The LED board 111 is a printed circuit board on which a transmission path for control signals from the light source control circuit 110 to the LED elements 112 is wired. The multiple LED elements 112 are arranged side by side in the X-axis direction on the LED board 111. Note that the light-emitting elements included in the light source module 11 are not limited to the LED elements 112, and other light-emitting elements may also be included. Light emitted by the LED elements 112 is irradiated onto the reading target 20 via the diffuser 113. The light source control circuit 110 may control the light intensity of the LED elements 112, for example, by pulse width modulation (PWM) control or current value control.

The light source module 11 may control the lighting of a single LED element 112 as illustrated in FIG. 4(b), or may control the lighting of multiple LED elements 112 as illustrated in FIG. 4(c). The light source control circuit 110 controls the lighting of the LED elements 112 for each minimum unit block of LED elements 112. For example, in the case of FIG. 4(b), the light source control circuit 110 can cause only one specific LED element 112 to emit light, while in the example shown in FIG. 4(c), it can cause only three specific LED elements 112 to emit light. Note that although the lighting control unit in FIG. 4(c) is three, the number of LED elements 112 in the minimum unit block that can be controlled to light is not limited to three.

The light source control circuit 110 lights up all of the LED elements 112 in the light source module 11 during the process in which the image reading device 10 generates general-purpose shading correction data 153. The light source control circuit 110 lights up specific LED elements 112, which are unit blocks of lighting control, during the process in which the image reading device 10 acquires a reference reflected light diffusion pattern (referred to as the reference individual light source lighting pattern 151) and a reflected light diffusion pattern of the reading target 20 (referred to as the reading target individual light source lighting pattern 152), which will be described later.

The AFE 120 converts the analog signal representing the reflected light input from the CCD 12 into a digital signal and inputs the digital signal to the image control circuit 130.

The image control circuit 130 extracts a specific area of the image data 200 output by the CCD 12 as the individual light source acquisition area 201, and uses this to generate the individual light source lighting pattern 152 for the reading target. The image control circuit 130 then extracts another specific area of the image data 200 as the image reading area 202, performs image correction on the image reading area 202, and outputs it to an external device via the external I/F 140. Shading correction is included in the image correction.

When the image scanner 1 is set to read an image using a white reference and a black reference, the image control circuit 130 acquires, via the CCD 12 and the AFE 120, a signal representing reflected light generated when a specific LED element 112 is turned on by the light source control circuit 110. The image control circuit 130 acquires this signal for each X coordinate value as a reference individual light source lighting pattern 151, and stores the acquired reference individual light source lighting pattern 151 in the memory area 150.

Figure 5 shows an example of a graph representing the reference individual light source lighting pattern 151. The horizontal axis of the graphs in Figures 5(a) and 5(b) represents the X coordinate value at which the CCD 12 captures reflected light, and the vertical axis represents the brightness of the reflected light captured by the CCD 12. In the graph in Figure 5(a), the X coordinate value at which the brightness of the reflected light is at its maximum corresponds to the X coordinate value at which the specific LED element 112 that is lit is located. Because reflected light is diffused by the reflecting surface, the graph representing the reference individual light source lighting pattern 151 exhibits a mountain shape as shown in Figure 5(a). The image control circuit 130 normalizes the reference individual light source lighting pattern 151 shown in Figure 5(a) so that the maximum brightness of the reflected light captured by the CCD 12 is "1".

The reference individual light source lighting pattern 151 after normalization is shown in Figure 5 (b). The image control circuit 130 calculates L_ref1, which represents the width of the range of X coordinate values in the normalized reference individual light source lighting pattern 151 where the brightness of the reflected light is equal to or greater than a predetermined threshold value 1. The image control circuit 130 calculates L_ref2, which represents the width of the range of X coordinate values in the normalized reference individual light source lighting pattern 151 where the brightness of the reflected light is equal to or greater than a predetermined threshold value 2. However, threshold value 2 is assumed to be smaller than threshold value 1.

When a target object 20, whose image is to be read by the image scanner 1, is placed, the image control circuit 130 acquires, via the CCD 12 and AFE 120, a signal representing reflected light generated when a specific LED element 112 is turned on by the light source control circuit 110. The image control circuit 130 acquires the signal for each X coordinate value in the individual light source acquisition area 201 as an individual light source lighting pattern 152 for the target object, and stores the acquired individual light source lighting pattern 152 for the target object in the memory area 150.

Figure 6 shows an example of a graph representing the reference individual light source lighting pattern 151. The horizontal and vertical axes in the graphs shown in Figures 6(a) and 6(b) are as described above with reference to Figures 5(a) and 5(b). In this graph, the X-coordinate value at which the reflected light has the maximum brightness is as described above with reference to Figure 5(a). Because reflected light is diffused on the reflecting surface (the surface of the object 20 to be read), the graph representing the individual light source lighting pattern 152 for the object to be read also exhibits a mountain shape as shown in Figure 6(a), similar to the graph shown in Figure 5(a). (In other words, the area where the mountain shape of Figure 6(a) is obtained when only a specific light source unit 11 is turned on is defined as the individual light source acquisition area 201, and this area is extracted.) The image control circuit 130 normalizes the individual light source lighting pattern 152 for the object to be read shown in Figure 6(a) so that the maximum brightness of the reflected light acquired by the CCD 12 is "1."

The normalized individual light source lighting pattern 152 for the reading target is shown in Figure 6 (b). The image control circuit 130 calculates L_eff1, which represents the width of the range of X coordinate values where the brightness of reflected light is equal to or greater than the threshold 1 described above, in the normalized individual light source lighting pattern 152 for the reading target. The image control circuit 130 calculates L_eff2, which represents the width of the range of X coordinate values where the brightness of reflected light is equal to or greater than the threshold 2 described above, in the normalized individual light source lighting pattern 152 for the reading target.

The image control circuit 130 generates shading correction data 154 for the read object based on the reference individual light source lighting pattern 151, the read object individual light source lighting pattern 152, and the general-purpose shading correction data 153 stored in the memory area 150. An example of the general-purpose shading correction data 153 is shown in FIG. 7. The vertical axis of the graph in FIG. 7 represents the correction value for the brightness of reflected light, and the horizontal axis represents the X-coordinate value. The general-purpose shading correction data 153 is shading correction data that does not depend on the light reflection characteristics (diffusion characteristics of reflected light) of the read object 20. The general-purpose shading correction data 153 is generated by a general function provided in the image reading device 10. In contrast, the shading correction data 154 for the read object is shading correction data that depends on the read object 20 and reflects the light reflection characteristics (diffusion characteristics of reflected light) of the read object 20.

The image control circuit 130 uses the above-mentioned L_ref1, L_ref2, L_eff1, and L_eff2 to calculate a correction value γ _eff for the general-purpose shading correction data 153, for example, as shown in the following equation (1).
γ _eff = {(L_ref1/L_ref2)-(Leff1/Leff2)}*T
...(1)
Here, in formula (1), "/" is an operator representing division, "-" is an operator representing subtraction, "*" is an operator representing multiplication, and "T" is a predetermined coefficient. The correction value γeff shown in formula (1) represents the difference between the diffusion rate of reflected light on a reflective surface when reading an image using a white reference and a black reference and the diffusion rate of reflected light on the surface of the object 20 to be read. The image control circuit 130 calculates the shading correction data 154 for the object to be read by performing a predetermined calculation using the correction value _γeff on the general-purpose shading correction data 153. Various calculations can be performed on the general-purpose shading correction data 153. For example, if the general-purpose shading correction data 153 represents a correction value for the luminance of reflected light relative to the X coordinate value (a value obtained by performing arithmetic operations on the observed luminance value), the image control circuit 130 adjusts the luminance correction value in the general-purpose shading correction data 153 based on the correction value _γeff .

For example, the image control circuit 130 generates the shading correction data 154 for the reading object using Seff(x) calculated by the following equation (3) applied to the sigmoid function shown in the following equation (2).
sigmoid(x)=1/{1+e^(-a*x)}...(2)
Here, in equation (2), e represents the base of the natural logarithm, a represents the gain in the sigmoid function, and ^ is an operator representing exponentiation.
Seff(x)=1/[1+e＾{-γ _eff *(x-(L1+L2)/2)}]
...(3)
In equation (3), Seff(x) represents the shading correction coefficient (applied to contrast adjustment) for the gradation value (luminance) x, and L1 and L2 represent the threshold 1 and threshold 2 related to the luminance of reflected light, respectively. When the value of _γeff is negative, the image control circuit 130 calculates Seff(x) by applying the absolute value of γeff to the inverse function of equation (3). For example, the image control circuit 130 generates shading correction data for the read object 154 by adding or multiplying the coefficient calculated by Seff(x) to the general-purpose shading correction data 153. An example of the shading correction data for the read object 154 is shown in FIG. 8. The vertical axis of the graph in FIG. 8 represents the correction value for the luminance of reflected light, and the horizontal axis represents the X-coordinate value.

In this way, the image reading device 10 generates shading correction data 154 for the read object by correcting the general-purpose shading correction data 153 based on the reference individual light source lighting pattern 151 obtained by lighting a specific LED element 112 and the individual light source lighting pattern 152 for the read object, taking into account the diffusion characteristics of the reflected light of the read object 20. This allows shading correction to be performed that flexibly responds to variations in the diffusion characteristics of the reflected light on the surface of the read object.

Memory area 150 is a non-volatile storage device such as an electronic memory or a magnetic disk. Memory area 150 stores a reference individual light source lighting pattern 151, a reading target individual light source lighting pattern 152, general-purpose shading correction data 153, and reading target shading correction data 154.

As will be explained next using the flowcharts in Figures 9 and 10, in this embodiment, the reading area of the CCD 12 is divided into a single light source acquisition area 201 and an image reading area 202, and the generation of the single light source lighting pattern 152 for the read object and shading correction data 154 for the read object and image reading are performed in a series of operations while reading the image of the read object 20. This makes it possible to automatically generate shading correction data 154 for the read object according to the characteristics of the read object 20 and apply it to image reading of the read object 20 without having to stop image reading of the read object 20 to obtain shading correction data.

(operation)
FIG. 9 is a flowchart illustrating an example of the preparation process according to the embodiment.
Prior to reading the image of the object 20, general-purpose shading correction data 153 and a reference individual light source lighting pattern 151 are obtained using specific white and black standards during manufacturing of the image reading device 10, and are stored in the memory area 150.
Specifically, the image reading device 10 places an image using a white reference and a black reference on the reading surface of the image scanner 1 (step S1). Next, the light source control circuit 110 turns on all of the LED elements 112 of the light source module 11 (step S2). Next, the image reading device 10 reads the image using the white reference and the black reference, generates general-purpose shading correction data 153 based on the image reading result, and stores and saves the generated general-purpose shading correction data 153 ( FIG. 7 ) in the memory area 150 (step S3).

Next, the light source control circuit 110 lights up a specific individual LED element 112 in the light source module 11 (step S4). For example, the light source control circuit 110 causes only one specific LED element 112 to emit light. Alternatively, the light source control circuit 110 causes the smallest unit block (e.g., three) of LED elements 112 that can be controlled to light up to emit light. The image reading device 10 reads the image using a white reference and a black reference. The image control circuit 130 acquires the diffusion pattern of reflected light represented by the image reading result, and stores and saves the acquired diffusion pattern of reflected light in the memory area 150 as a reference individual light source lighting pattern 151 (Figure 5) (step S5). This completes the preparation process.

Next, a process when an image of the object 20 is actually read will be described.
FIG. 10 is a flowchart illustrating an example of a process for generating shading correction data according to the embodiment.
First, in the image scanner 1, the object 20 is placed on the reading surface and transported as shown in FIG. 2 (step S11). Next, the light source control circuit 110 turns on a specific single LED element 112 in the light source module 11 (step S12). This process is the same as step S4 in FIG. 9. Next, the control board 100 controls the CCD 12 to capture an image of the object 20 (step S13). The CCD 12 outputs the captured image data 200 to the image control circuit 130 via the AFE 120. The image control circuit 130 then cuts out and extracts a single light source acquisition area 201 from the image data (step S14).

Next, the image control circuit 130 acquires the individual light source lighting pattern 152 (FIG. 6) for the reading target from the individual light source acquisition area 201 (step S15). Next, the image control circuit 130 reads the reference individual light source lighting pattern 151 (FIG. 5) stored in the memory area 150 (step S16). Next, the image control circuit 130 calculates the individual light source lighting pattern correction value γ _eff from the reference individual light source lighting pattern 151 and the individual light source lighting pattern 152 for the reading target using equation (1) (step S17).

Next, the image control circuit 130 reads out the general-purpose shading correction data 153 (FIG. 7) stored in the memory area 150, and reflects the individual light source lighting pattern correction value γ _eff calculated in step S17 (step S18), thereby generating shading correction data 154 (FIG. 8) for the read object (step S19). The image control circuit 130 stores and preserves the generated shading correction data 154 for the read object in the memory area 150.

Next, the light source control circuit 110 turns on all the light source modules 11 for image reading (step S20). The image reading device 10 reads the image using the shading correction data 154 for the read object generated in step S19. For example, the shading correction data 154 for the read object is applied as a filter (step S21), and the CCD 12 captures the image of the read object 20 (step S22). The CCD 12 outputs image data 200 to the image control circuit 130. The image control circuit 130 extracts an image reading area 202 from the image data 200 (step S23), performs shading correction on the extracted image reading area 202 using the shading correction data 154 for the read object, and outputs the result as a read image by the image scanner 1 to the outside via the external I/F 140 (step S24).

After this, the light source module 11 repeatedly switches on individual light sources and all light sources, generating shading correction data 154 for the object being read each time and reading the image.

The above embodiment is merely an example, and the following configurations may be used. For example, while a mirror 14 is provided in the optical path of the image reading device 10, a configuration without a mirror 14 is also possible. The memory area 150 may store three or more individual light source lighting patterns. The timing for generating the shading correction data 154 for the read object to be actually used can be set arbitrarily. For example, the shading correction data 154 for the read object may not be stored in the memory area 150, but may be generated each time an image is read. Alternatively, the shading correction data 154 for the read object may be generated each time the reading conditions for the read object 20 are changed (e.g., when the type of the read object 20 is changed from material 1 to material 2). Alternatively, the shading correction data 154 for the read object may be generated each time a predetermined number of image readings are performed (e.g., once every several image readings). The CCD 12 may be an area image sensor instead of a line image sensor. The light source module 11 may be an LED, but may also be another type of light-emitting element. The light source does not have to be integrated with the image reading device 10, as long as it is fixed within the configuration of the image scanner 1. The number of light source modules 11 can be one unit or multiple units, as long as it is possible to control switching between lighting a specific minimum unit block (which can be one or multiple units) and lighting all the lights. Also, although the image reading area 202 and the individual light source acquisition area 201 are different areas, there may be an overlapping area between the two.

(effect)
As described above, when reading an image of the reading object 20, the image reading device 10 of this embodiment cuts out the single light source acquisition area 201 from the image data 200, generates shading correction data 154 for the reading object using the cut-out single light source acquisition area 201, cuts out the image reading area 202 from the image data 200, and performs shading correction by applying the shading correction data 154 for the reading object to the cut-out image reading area 202.

For example, in a production line that handles many types of read objects, such as metal plates, shading correction data for each read object 20 must be acquired and changed each time. However, in an actual production site, it is difficult to generate and manage shading correction data for each individual read object 20. Furthermore, if shading correction data were to be provided for each read object, standardization of the production line would be impossible and equipment costs would increase. In contrast, according to this embodiment, shading correction data 154 for each read object 20 can be automatically acquired and applied, allowing for efficient shading correction to be performed according to the read object 20.

More specifically, because the shading correction data 154 for the read object can be generated directly from the read object 20, there is no need to place a white reference and a black reference on the reading surface to acquire the shading correction data. Therefore, there is no need to temporarily suspend the production line to reacquire the shading correction data.

In addition, since shading correction data 154 for the read object can be generated directly from the read object 20, shading correction data 154 for the read object can be obtained that corresponds to reading conditions such as variations in the diffusion characteristics of reflected light on the surface of the read object, thereby improving the quality of the read image.

In addition, since the acquisition of the individual light source lighting pattern 152 for the reading target and image reading can be performed in a single operation, there is no need to prepare shading correction data for each reading target in advance, which is expected to reduce implementation costs.

Furthermore, since the generation of shading correction data 154 for the read object can be performed in a series of operations along with image reading, different types of read objects 20 can be introduced into the same production line, which is expected to reduce equipment costs. For example, the shading correction data generation method of this embodiment can also be applied to image reading devices used for inspection in the manufacturing industry.

(Minimum configuration)
FIG. 12 is a block diagram showing the configuration of the image reading device 10 having the minimum configuration.
The image reading device 10 is an image reading device that generates general-purpose shading correction data by reading an image using a white reference and a black reference with all of a plurality of light sources turned on, and is equipped with a first acquisition means 801, a second acquisition means 802, a generation means 803, and a reading means 804.
The first acquisition means 801 acquires the diffusion state of the first reflected light generated by irradiating light from a specific light source among a plurality of light sources when reading an image using a white reference and the black reference.
The second acquisition unit 802 acquires the diffusion state of the second reflected light generated by irradiating the image reading target with light from the specific light source.
The generating means 803 generates shading correction data for the read object that depends on the read object, based on the diffusion state of the first reflected light, the diffusion state of the second reflected light, and the general-purpose shading correction data.
The reading unit 804 reads an image by using the shading correction data for the read object while irradiating the read object with light from all of the plurality of light sources.

FIG. 14 is a flow chart showing the operation of an image reading apparatus having a minimum configuration.
The image reading device 10 generates general-purpose shading correction data (step S801). The first obtaining unit 801 obtains the diffusion state of the first reflected light (step S802). The second obtaining unit 802 obtains the diffusion state of the second reflected light (step S803). The generating unit 803 generates shading correction data for the reading object (step S804). The reading unit 804 reads the image of the reading object (step S805).

Note that part of the image reading device 10 in the above-described embodiment may be implemented by a computer. In this case, a program for implementing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be loaded into a computer system and executed. Note that the "computer system" referred to here refers to a computer system built into the image reading device 10, and includes hardware such as the OS and peripheral devices.

In addition, "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording medium" may also include devices that dynamically store programs for a short period of time, such as communication lines when transmitting programs over networks like the Internet or communication lines like telephone lines, or devices that store programs for a fixed period of time, such as volatile memory within computer systems that serve as servers or clients in such cases. Furthermore, the above-mentioned programs may be those that implement some of the functions described above, or may be those that can implement the functions described above in combination with programs already stored in the computer system.

Furthermore, part or all of the image reading device 10 in the above-described embodiment may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each functional unit of the image reading device 10 may be individually implemented as a processor, or part or all of them may be integrated into a processor. Furthermore, the integrated circuit method is not limited to LSI, and may be implemented using a dedicated circuit or a general-purpose processor. If an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, an integrated circuit based on that technology may be used.

Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design modifications can be made without departing from the spirit of the invention. Furthermore, one aspect of the present invention can be modified in various ways within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of the present invention. Furthermore, configurations in which elements described in the above embodiments and variations are substituted with elements that achieve the same effect are also included.

1... Image scanner 10... Image reading device 11... Light source module 12... CCD
13: Lens 14: Mirror 15: Cover glass 20: Reading object 30: Reading object conveying system 100: Control board 110: Light source control circuit 120: AFE
130: Image control circuit 140: External I/F
150: Storage area 151: Reference individual light source lighting pattern 152: Reading target individual light source lighting pattern 153: General-purpose shading correction data 154: Reading target shading correction data 200: Image data 201: Individual light source acquisition area 202: Image reading area

Claims (8)

An image reading device that generates general-purpose shading correction data by reading an image using a white reference and a black reference while all of a plurality of light sources are turned on,
a first acquisition means for acquiring a diffusion state of a first reflected light generated by irradiating light from a specific light source among the plurality of light sources in a state in which reading of an image using the white reference and the black reference is executed;
a second acquisition means for acquiring a diffusion state of second reflected light generated by irradiating light from the specific light source in a state in which reading of an image reading target is being executed;
a generating means for generating shading correction data for the read object, the shading correction data being dependent on the read object, based on the diffusion state of the first reflected light, the diffusion state of the second reflected light, and the general-purpose shading correction data;
a reading unit that, in a state where reading of an image reading target is executed, performs image reading using the shading correction data for the reading target while irradiating light from all of the plurality of light sources;
Equipped with
the second acquisition means extracts a predetermined single light source acquisition area from the image of the object to be read, the single light source acquisition area including an area where the luminance of the reflected light generated by irradiation with light from the specific light source is maximum, and acquires a diffusion state of the second reflected light in the extracted single light source acquisition area;
the reading means cuts out, from the image of the read object, a remaining area obtained by cutting out the single light source acquisition area or an area including a part of the single light source acquisition area as an image reading area, and performs shading correction on the cut-out image reading area using the shading correction data for the read object;
Image reading device. Each time the image of the object to be read is read,
the second acquisition means acquires a diffusion state of the second reflected light,
the generating means generates shading correction data for the reading object,
performing shading correction using the shading correction data for the read object;
2. The image reading device according to claim 1. Each time the image reading of the reading target is performed a predetermined number of times,
the second acquisition means acquires a diffusion state of the second reflected light,
the generating means generates shading correction data for the reading object,
performing shading correction using the shading correction data for the read object;
3. The image reading device according to claim 1 or 2. Each time the reading conditions of the reading object are changed,
the second acquisition means acquires a diffusion state of the second reflected light,
the generating means generates shading correction data for the reading object,
performing shading correction using the shading correction data for the read object;
3. The image reading device according to claim 1 or 2. a light source control unit that controls the lighting of only a specific light source among the plurality of light sources or the lighting of all of the plurality of light sources,
the light source control means controls some of the light emitting elements constituting the plurality of light sources as the specific light source;
3. The image reading device according to claim 1 or 2. further comprising a storage means for storing the diffusion state of the first reflected light, the diffusion state of the second reflected light, the general-purpose shading correction data, and the shading correction data for the read object;
3. The image reading device according to claim 1 or 2. generating general-purpose shading correction data by reading an image using a white reference and a black reference with all of the plurality of light sources turned on;
acquiring a diffusion state of a first reflected light generated by irradiating light from a specific light source among the plurality of light sources in a state in which reading of an image using the white reference and the black reference is executed;
acquiring a diffusion state of second reflected light generated by irradiating light from the specific light source in a state in which reading of an image reading target is being executed;
generating shading correction data for the read object that depends on the read object based on the diffusion state of the first reflected light, the diffusion state of the second reflected light, and the general-purpose shading correction data;
a step of reading the image by using the shading correction data for the read object while irradiating light from all of the plurality of light sources in a state in which reading of the image read object is executed;
and
In the step of acquiring the diffusion state of the second reflected light, a predetermined single light source acquisition area including an area where the luminance of the reflected light generated by irradiation with light from the specific light source is maximum is cut out from the image of the reading target, and the diffusion state of the second reflected light in the cut-out single light source acquisition area is acquired;
In the step of reading the image, a remaining area obtained by cutting out the single light source acquisition area from the image of the read object, or an area including the single light source acquisition area as a part thereof, is cut out as an image reading area, and shading correction is performed on the cut-out image reading area using shading correction data for the read object.
Image reading control method. A program that causes a computer to execute the image reading control method described in claim 7.