JP2014158247A - Image input device and image input method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image input device where a distance between an image pickup section and an imaging target is separated, which reduces influence of peripheral environment.SOLUTION: An image input device includes: an image sensor for detecting reflected light from a target; and an image processing section for acquiring an image in response to the reflected light detected by the image sensor. The image processing section estimates a level of the reflected light in a case where the target is set to be an object under a first illumination condition on the basis of a first level change amount of the reflected light when a second illumination condition is added in a case where the target is set to be a reference target under the first illumination condition and a second level change amount of the reflected light when the second illumination condition is added in a case where the target is set to be a prescribed object under a third illumination condition.

Description

  The present invention relates to an image input apparatus that inputs an image while an original is stationary on the apparatus and a method thereof, and more particularly to a shadow correction process of a document camera type or a stand type image input apparatus in which the original is separated from an image capturing unit. .

  Here, the shadow correction is correction performed in a document camera type or stand type image input device in which the document and the image capturing unit are separated from each other. When an image of a document is input to an electronic device, light of different intensity is reflected on the document due to uneven illumination or shadows of objects, and when the reflected light is captured as an image, the light of this different intensity The process of removing the influence is called shadow correction.

  As a basic configuration of shadow correction performed in the image input device, an image capturing unit, an image storing unit for storing shadow data, and image capturing each time based on the stored shadow data An arithmetic unit that performs arithmetic processing on the data of the read image input by the unit is provided.

  As shadow data, a white reference sheet with no unevenness is prepared in advance and is read by an image input device. If there is a shadow at the time of reading, the density level value of that portion is low, so it is stored as shadow data.

  A method of performing shadow correction by performing arithmetic processing on a read image and stored shadow data for a document image input by an image capturing unit is performed.

  When illumination unevenness or shadow density or position changes, a correction program is started to update the stored shadow data, and a white reference sheet dedicated to adjustment is placed on the device and the image is displayed. Once acquired, the newly changed illumination unevenness and shadow situation must be stored in the shadow correction table as a density difference appearing in the image of the white reference sheet.

  In this method, a special white reference sheet is required, and when acquiring an image of a white reference sheet, it is necessary to acquire it in a state where no human shadow or hand enters, and save it as a shadow correction table. There was a problem. In actual financial operations, it is necessary to call a maintenance person who has taken the shadow correction method as a maintenance education and to change the shadow correction.

  As an example for solving such a problem, a technique as disclosed in Patent Document 1 is disclosed.

  In Patent Document 1, in image input, a main scan and a pre-scan that captures an image before the main scan are performed twice, a shadow correction region is identified by analyzing the image obtained at the time of the pre-scan, and A technique for performing the correction is disclosed. Unlike the method of creating a correction table in advance, prescanning is performed when a document image is input each time. In the correction method, a dark part is set as a shadow area by pre-scanning at a low resolution, and an area that is a shadow part by pre-scanning is corrected for a main scan image read at a high resolution.

  Japanese Patent Application Laid-Open No. 2004-228688 discloses a technique for reducing illumination unevenness by changing the light emission intensity of an LED constituting a light source unit of an image input device.

  Furthermore, in Patent Document 3, when acquiring shadow data based on the surrounding brightness environment, the shadow data is not always used from the white reference sheet, but is calculated from the density difference of the image on the document table itself on which nothing is placed as a document. A technique is disclosed in which shadow correction is performed by estimating fluctuations in the above.

JP 2011-035876 A JP 2001-298595 A JP 2008-199556 A

  In the technique described in Patent Document 1, the pre-scan performs image acquisition twice, and calculation for analyzing the shadow of the image is performed between the first time and the second time. For this reason, compared with the case where an image is acquired once, there is a problem that it takes a long time to acquire one image for completing the shadow correction.

  Further, in the technique described in Patent Document 2, when a shadow that differs in a complicated manner depending on a position or a density difference due to the shadow is steep, the shadow is erased corresponding to a complicated shape, or a steep density difference is caused. There was a problem that it was difficult to erase in correspondence.

  Furthermore, in the technique described in Patent Document 3, the shadow correction is performed by estimating the fluctuation of the shadow data from the density difference of the image on the original platen itself on which nothing is placed, and an extremely dark original is placed. In this case, there is a problem that it cannot be distinguished from the fact that no manuscript is placed.

  An object of the present invention is to provide an image input apparatus and method that solve the above-described problems.

  In one aspect, the present invention provides an image input device, and includes an image sensor that detects reflected light from an object, and an image processing unit that acquires an image based on the reflected light detected by the image sensor. The image processing unit includes a first level change amount of reflected light when the second illumination condition is added when the object is a reference object under the first illumination condition. Based on the second level change amount of the reflected light when the second illumination condition is added in the case where the object is a predetermined target under the third illumination condition, It is characterized in that a level of reflected light is estimated under the first illumination condition when the object is the object.

  In order to solve the above-described problem, the image input device according to the first aspect of the present invention detects an illumination device that irradiates light on an object, an image sensor that detects reflected light from the object, and an image sensor. An image processing unit for processing the reflected light is included. Then, when the object is a white reference sheet, the image processing unit determines the difference between the level of reflected light when the lighting device is lit and the level of reflected light when the lighting device is not lit, By calculating using the difference between the level of reflected light when the lighting device is lit and the level of reflected light when the lighting device is not lit and a predetermined correction value for a predetermined object The method is characterized in that an image of a predetermined object and having no influence of the surrounding environment is obtained.

In yet another aspect, the present invention provides an image input method, based on a reflected light detection step for detecting reflected light from an object, and reflected light detected by the reflected light detection step, An image processing step for acquiring an image, and in the image processing step, the reflected light when the second illumination condition is added in the case where the object is a reference object under the first illumination condition. The second level of reflected light when the second illumination condition is added when the target is a predetermined target under the first level change amount and the third illumination condition Based on the amount of change, the level of reflected light is estimated under the first illumination condition when the target is the target.
Note that the present method is linked to a specific machine called an image input device having an image sensor and an image processing unit.

  In another viewpoint, the present invention provides an image input method, and in the image input method of an image input device having an image sensor, an illumination device, and an image processing unit, the image sensor when the illumination device is not lit. The level value of the reflected light from the white reference sheet in the predetermined pixel above, the level value of the reflected light from the white reference sheet in the predetermined pixel on the image sensor when the lighting device is lit, and the lighting device From the level value of the reflected light from the predetermined object at the predetermined pixel on the image sensor when not lit, and the predetermined object at the predetermined pixel on the image sensor when the lighting device is lit A step of observing the reflected light level value, and a step of performing a predetermined calculation on each reflected light level value obtained from the observed step It is characterized by having a. Note that the invention is different from reducing the darkness of the shadow itself with the illumination device that irradiates the object with light.

  An effect of the present invention is that, in a document camera or a stand-type image input device, when the shadow density or the shadow position changes, the shadow correction can be easily updated.

It is a block diagram which shows the structure of the image input device in the 1st Embodiment of this invention. It is a perspective view which shows the detailed structure of the image input device in the 1st Embodiment of this invention. (A), (b) It is a figure explaining the state of the change of the reflectance density | concentration by the influence of the shadow in the 1st Embodiment of this invention. (A), (b), (c), (d) It is a figure explaining the state of the reflectance density | concentration in the original surface by the 1st Embodiment of this invention. (A), (b) It is a perspective view explaining the example of the illuminating device in the 1st Embodiment of this invention. It is a perspective view which shows the structure of the image input device in the 2nd Embodiment of this invention. (A), (b) It is a figure explaining the relationship between the wavelength of light and illumination in the 3rd and 4th embodiment of this invention. It is a figure explaining the state which smoothes the pixel of the image sensor in the 5th Embodiment of this invention. It is a figure explaining the field transfer system of the image sensor in the 6th Embodiment of this invention. It is a figure for demonstrating the outline | summary of one Embodiment.

  First, an outline of an embodiment will be described with reference to FIG. Note that the reference numerals of the drawings attached to the outline are attached to the respective elements for convenience as an example for facilitating understanding, and the description of the outline is not intended to be any limitation.

  As an example, an image input apparatus 100 shown in FIG. 10 is provided. The image input device 100 includes an image sensor 101 and an image processing unit 102. The image sensor 101 detects reflected light from the object. The image processing unit 102 acquires an image based on the reflected light detected by the image sensor.

  First, the image processing unit 102 calculates the first level change amount of the reflected light when the second illumination condition is added in the case where the object is a reference object under the first illumination condition. calculate. For example, a state in which the object is newly illuminated under a predetermined illumination condition (first illumination condition) may be a state in which the second illumination condition is added to the first illumination condition. Note that the reference object is preferably an object having a uniform reflectance. For example, the reference object is preferably a white reference sheet.

  Next, the image processing unit 102 uses the second level change amount of the reflected light when the second illumination condition is added in the case where the target object is the predetermined target under the third illumination condition. Is calculated. The third illumination condition is preferably an illumination condition different from the first illumination condition and the second illumination condition.

  Then, the image processing unit 102 sets the target object as the target object under the first illumination condition based on the first level change amount of the reflected light and the second level change amount of the reflected light. Estimate the level of reflected light in the case. That is, the image processing unit 102 can estimate the level of reflected light under an illumination condition (first illumination condition) different from the illumination condition (third illumination condition) in which the image sensor 101 detects reflected light.

  For example, it is assumed that the first illumination condition is an illumination condition in which no shadow is generated on the object. On the other hand, it is assumed that the third illumination condition is an illumination condition in which a shadow is generated on the object. In that case, the image processing unit 102, based on the level of reflected light detected in a state where the object has a shadow (third illumination condition), an illumination condition (first illumination condition) in which no shadow occurs. The level of reflected light at can be estimated. Specifically, the image processing unit 102 determines the level of reflected light when the same illumination condition (second illumination condition) is added for each of the illumination condition in which a shadow does not occur and the illumination condition in which a shadow occurs. calculate. Then, the image processing unit 102 estimates the reflected light levels of different objects by numerical calculation under illumination conditions in which no shadow is generated.

  Here, since the image input apparatus 100 only needs to acquire the target image once, it takes less time to complete the shadow correction than the technique described in Patent Document 1. Further, unlike the technique described in Patent Document 2, the image input apparatus 100 does not need to consider the shape of a shadow. In addition, unlike the technique described in Patent Document 3, the image input apparatus 100 is not affected by the color of the correction target image.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the reference object is described as a white reference sheet. However, this is not intended to limit the reference object to the white reference sheet.
(First embodiment)
FIG. 1 is a block diagram showing a configuration of an image input apparatus according to the first embodiment of the present invention.

  In FIG. 1, the present invention includes a lighting device 1, an image sensor 5, and an image processing unit 10. As shown in FIG. 1, the illumination device 1 irradiates light on the document that is the object 2, and the reflected light from the document is read by the image sensor 5. In the image sensor 5, input light is photoelectrically converted and image processing is performed by the image processing unit 10 to generate image data.

  Specifically, when the object 2 is a white reference sheet, the image processing unit 10 reflects the level of reflected light when the lighting device 1 is lit and the level of reflected light when the lighting device 1 is not lit. And the difference between the level of reflected light when the lighting device 1 is lit when the object 2 is a predetermined target and the level of reflected light when the lighting device 1 is not lit. The correction value is used for calculation. As a result, the image processing unit 10 can contribute to obtaining an image of a predetermined object and having no influence of the surrounding environment.

  FIG. 2 is a perspective view showing a detailed configuration of a specific image input apparatus according to the first embodiment of the present invention.

  2, the image input apparatus of the present invention includes an image pickup unit 3 including an image sensor 5, a lens 4 that forms incident light on the image sensor 5, and a document table 6 on which a document to be imaged is placed. And an illuminating device 1 for irradiating the document surface. In addition, a stand unit 7 is provided to maintain a certain distance without bringing the document surface on the document table and the image pickup unit 3 into close contact with each other. Further, the image processing apparatus 10 includes a calculation unit 11 that calculates the density level value of the image and an image storage unit 12 that stores the image data.

  The image storage unit 12 may be a memory in the apparatus, an HDD or a semiconductor memory controlled from a personal computer (PC). Moreover, the whole is illuminated with the installation environment illumination 20.

  The processing of the calculation unit 11 of the image processing apparatus 10 will be described with reference to FIGS.

The white reference sheet 30 as the object 2 is placed on the document surface of the image input apparatus according to the present invention, and attention is paid to the reflectance and brightness at predetermined points on the surface.
As shown in FIG.
Reflectance of the white reference sheet 30 at a predetermined point: Ni
Brightness of the installation environment at the time of calibration at the above point: Li
And

Brightness of a spot by the lighting device 1 according to the present invention: Lr
Then,
The lighting device 1 is further turned on under the brightness of the installation environment at the time of calibration, and the brightness at a certain point is: Li + Lr
Indicated by

The level value of the reflected light observed by the image input device from a predetermined point on the document surface is reflectance × brightness = level assuming that there is no stagnation or smoke in the normal office space. As shown in (a),
The level value of reflected light observed at a point on the white reference sheet 30 at the brightness at the time of calibration: P (i, i) is
P (i, i) = Ni × Li (1)
It is expressed.

Further, as shown in FIG. 4B, in addition to the brightness at the time of calibration, the lighting device 1 is turned on, and the reflected light level value observed at a point on the white reference sheet 30: P (i, ir) Is
P (i, ir) = Ni * (Li + Lr) (2)
It is expressed.

  Next, it is assumed that there is a shadow that is different from that at the time of installation.

  In the case where there is a shadow as shown in FIG. 3B, the brightness of illuminating the document surface also changes due to the shadow, and in addition, an arbitrary reflectance density, which is the target, is not the white reference sheet 30 during operation. The form you have will be placed on the platen.

Brightness to illuminate the document surface with illumination changed from the time of calibration due to shadows, etc .: Ly
Reflectivity of any form on the manuscript surface (printing with arbitrary darkness): Nx
Then, as shown in FIG. 4C, the reflected light level value P (x, y) observed from an arbitrary form during operation is:
P (x, y) = Nx × Ly (3)
It becomes. Next, when the lighting device 1 according to the present invention is lit under this changed illumination, the brightness of the lighting device 1 is not affected by changes such as shadows,
Ly + Lr
Indicated by

In addition to this changed illumination, the lighting device 1 is turned on, and the reflectivity level of an arbitrary form: Nx is the reflected light level value observed by the device, as shown in FIG.
P (x, yr) = Nx × (Ly + Lr) (4)
It becomes.
What is required is the level value of the reflected light observed from the density Nx of an arbitrary form by the brightness Li when there is no influence of the shadow,
P (x, i) = Nx × Li (5)
Is the level value of the reflected light that is required.
The reflected light level value P (x, i) is an observation value input to the apparatus so far, P (i, i), P (i, ir), P (x, y), P (X, yr)
If it can be shown, it will be found.
Subtracting both sides of (1) from (2)
P (i, ir) −P (i, i) = Ni × Lr (6)
Subtracting both sides from (4) to (3)
P (x, yr) −P (x, y) = Nx × Lr (7)
It becomes.
Substituting (1) for (6) and erasing Ni,
P (i, ir) −P (i, i) = P (i, i) × Lr / Li (8)
Substituting (7) and (8) into (5), which is the originally obtained value,
P (x, i) = (P (x, yr) −P (x, y)) / (P (i, ir) −P (i, i)) × P (i, i) (9) )
Thus, P (x, i) can be represented only by observed values.

  In the above description, for the sake of simplicity, the level value observed from the image sensor in a brightness state where there is no light is assumed to be zero, and the brightness and the level value are described as a simple proportional relationship. However, in an actual image sensor, the brightness and level value may not be zero even when there is no light.

  In order to obtain a proportional relationship, it is necessary to provide a black level correction value when the brightness is zero. By adding the black level correction value: Pb to the observed value, more accurate shadow correction can be performed.

That is, in (1), (2), (3), (4), (5) that appeared in the description of the operation,
P (i, i) = Ni × Li + Pb (1) ′
P (i, ir) = Ni x (Li + Lr) + Pb (2) '
P (x, y) = Nx × Ly + Pb (3) ′
P (x, yr) = Nx × (Ly + Lr) + Pb (4) ′
P (x, i) = Nx × Li + Pb (5) ′
far.

  For Pb, Li is 0 in (1) ′, that is, use the value observed when no light is given, or (1) is prepared from a plurality of observed values by preparing a known concentration form, Li may be 0. Alternatively, as another method, in (1), an accurate illuminometer is prepared and the level value observed by the apparatus is measured while observing the brightness, and Li is set to 0 from the obtained approximate line. good.

Using Pb determined in this manner and recalculating (9), which is the level value to be calculated again, using the equation:
P (x, i) = (P (x, yr) −P (x, y)) / (P (i, ir) −P (i, i)) ×
(P (i, i) −Pb) + Pb (9) ′
It becomes.

  An embodiment of the lighting device 1 according to the present invention is shown in FIGS. The illuminating device 1 is preferably irradiated with illumination light as evenly as possible on the document surface at a position where no shadow is formed on the document surface. In FIG. 5A, an LED element is provided as a light emitter, and a lens that efficiently irradiates the document surface by changing the optical path from the LED element. In addition, an LED drive circuit that applies current to the LED element and a blinking control circuit that sends a signal to the LED drive circuit to turn on the lighting device light when necessary and to turn off the light when not necessary.

FIG. 5B shows another embodiment of the lighting device 1. The LED has a structure in which an LED element and a lens are integrated, and five LEDs are arranged to constitute one lighting device. The lighting device is provided with an LED drive circuit and a blinking control circuit as described above, and the blinking of the illumination is controlled in response to the blinking control signal.
(Second Embodiment)
FIG. 6 is a perspective view showing the configuration of the image input apparatus according to the second embodiment of the present invention.

  Compared to the diagram of the first embodiment in FIG. 2, a storage unit 13 for storing a correction table is added. The same components as those in FIG. 2 are given the same numbers.

  In order to calculate the reflected light level value P (x, i) that does not have the influence of the shadow for the density Nx of an arbitrary form in the above equation (9) ', an arbitrary form is placed. It was necessary to observe the image P (x, y) to be acquired. In addition, it is necessary to observe P (x, yr), which can be obtained by turning on the lighting device 1 for the form.

  However, if the lighting that has changed since the calibration occurred and there is no change after that, update the shadow correction table when the shadow changes, so that each time, It is not necessary to blink the light, and it is possible to remove the influence of the shadow.

  That is, an updated shadow correction table is created by the following calculation for illumination that has changed due to the occurrence of a shadow or the like since calibration.

  The shadow correction table is to obtain the level value P (i, y) obtained by the reflectance of the white reference sheet 30 density: Ni in the changed illumination: Ly.

As before,
P (i, i) = Ni × Li + Pb (1) ′
P (i, ir) = Ni x (Li + Lr) + Pb (2) '
P (x, y) = Nx × Ly + Pb (3) ′
P (x, yr) = Nx × (Ly + Lr) + Pb (4) ′
From the above, P (i, y) is represented by P (i, i), P (i, ir), P (x, y), P (x, yr), Pb.
P (i, y) = (P (x, y) −Pb) × (P (i, ir) −P (i, i)) / (P (x, yr) −P (x, y)) + Pb ... (10)
It becomes.

  By saving the P (i, y) value of (10) as an updated correction table and dividing it from the level value obtained by inputting an image of an arbitrary form by the updated correction table value. The effect of changing after the shadow calibration can be eliminated. After that, it is only necessary to obtain a level value of the reflected light by applying a uniform magnification so that the brightest part has a desired brightness.

When obtaining the level value P (x, i) of the document reflected light in the general ceiling lamp illumination in a state free from the influence of the surrounding environment, the formula: P (x, i) = (P (x, y) −Pb) / ( P (i, y) -Pb) * (P (i, i) -Pb) + Pb
Thus, it can be obtained by performing calculation in the arithmetic unit.

According to the second embodiment, compared to the first embodiment, the level value of the reflected light from which the influence of the surrounding environment is removed can be obtained without causing the lighting device 1 to blink each time.
(Third embodiment)
A third embodiment of the present invention will be described with reference to FIGS. 7 (a) and 7 (b).

  The third embodiment of the present invention is characterized in that the wavelength region of the illumination device 1 is in the infrared as compared with the first and second embodiments. Other configurations are the same as those in the first and second embodiments, and thus are omitted.

  About the illuminating device 1, a center wavelength does not necessarily need to be in a visible region.

  As shown in FIG. 7A, the sensitivity range of the image sensor according to the present invention, the curve of the form density in which the density of an arbitrary form appears, and the overlap of the wavelength curve of the illumination that creates the surrounding environment, It suffices if a wavelength region exists. For example, as an example, an infrared LED having a center wavelength at a wavelength of 870 nm can be used.

As shown in FIG. 7A, regarding the monochrome sensor among the image sensors, there is an overlap with the spectral wavelength of the image sensor in the infrared region. On the other hand, as shown in FIG. 7B, in the case of a sensor having a primary color filter of a general Bayer arrangement among color image sensors, there is an overlap with the spectral region of the image sensor in the infrared region. Therefore, it is possible to use an infrared LED as the lighting device 1.
(Fourth embodiment)
A fourth embodiment according to the present invention will be described with reference to FIGS.

  The fourth embodiment of the present invention is characterized in that the wavelength region of the illumination device 1 is in the ultraviolet as compared with the first and second embodiments. Other configurations are the same as those in the first and second embodiments, and thus are omitted.

  About the illuminating device 1, a center wavelength does not necessarily need to be in a visible region.

  As shown in FIG. 7A, for example, an ultraviolet LED having a center wavelength at a wavelength of 380 nm can be used as the illumination device 1. The ultraviolet LED to be used has the wavelength region of the illumination device 1 in the overlap of the sensitivity region of the image sensor according to the present invention, the curve of the form density in which the density of an arbitrary form appears, and the wavelength curve of the illumination that creates the surrounding environment. That's fine.

  As shown in FIG. 7A, regarding the monochrome sensor among the image sensors, there is an overlap with the spectral wavelength of the image sensor in the ultraviolet region. On the other hand, as shown in FIG. 7B, in the case of a sensor having a primary color filter of a general Bayer arrangement among color image sensors, in the ultraviolet region, only in the case of a blue filter, the spectral region with the image sensor is changed. There is an overlap.

For this reason, when the color image sensor and the illumination device 1 in the ultraviolet region are used, processing may be performed using blue pixels.
(Fifth embodiment)
The fifth embodiment will be described with reference to FIG.

  In the fifth embodiment, the use method of the pixels included in the image sensor is different. Other configurations are the same as those in the first and second embodiments, and thus are omitted.

  It is not necessary to use a shadow correction table having values for correcting each pixel of the image sensor. For example, the value of the updated shadow correction table obtained in the above embodiment is averaged over four pixels and set as a representative value. In the shadow correction table, four pixels are set to the same value and the shadow of the above-described representative value update is updated. A correction table is used.

  FIG. 8 shows a case where the image sensor element is a color element with a Bayer arrangement. In this case, for color elements of the same color, the average value of two pixels, such as an average value of neighboring elements, for example, an average value of G1 and G2 pixels, or an average value of G3 and G4 pixels, is used as a representative value. It is possible to use a correction table.

In this way, the memory required for the shadow correction table can be reduced, and the memory access time is one-fourth in the former example and half in the latter example. Can be fast.
(Sixth embodiment)
A sixth embodiment will be described with reference to FIG. In the sixth embodiment, the method of using pixels included in the image sensor is different. Other configurations are the same as those in the first and second embodiments, and thus are omitted.

  FIG. 9 is a diagram of a CCD sensor in which charges are transferred in units of fields. Here, the entire screen is divided into six fields per line, and fields with the same number are transferred at the same time.

  As shown in FIG. 9, in a CCD sensor transferred in field units, one field is exposed with a lighting device (not shown) using an LED turned on, and another field is formed using an LED. An image is acquired by performing exposure with the illumination device turned off.

  Then, the level value of the reflected light of a predetermined pixel obtained from one field of both is acquired, and this value is used as a representative value of the level of the reflected light in the vicinity. If an illumination device using an LED is used, it can be turned on and off in a short period of time when the field is switched. Then, within a short period of time when the field is switched, as a strip-shaped partial image covering the entire screen, a partial image in which the lighting device using the LED is turned on and a partial image in the case of being turned off are acquired. Can do.

  Since it is a short time during which one field is switched as compared with the acquisition and transfer time of the whole image, it is possible to reduce the fluctuation of the influence of the ceiling lamp illumination and the environment surrounding the apparatus. For this reason, the processing accuracy of the shadow correction according to the present invention can be improved, and since two types of partial images can be acquired at high speed, an image for performing shadow correction can be acquired at high speed.

  A part or all of the above embodiments can be described as in the following supplementary notes, but is not limited thereto.

  (Supplementary Note 1) An image sensor that detects reflected light from an object and an image processing unit that acquires an image based on the reflected light detected by the image sensor. The image sensor includes: In the case where the object is a reference object under the first illumination condition, the first level change amount of the reflected light when the second illumination condition is added, and the third illumination condition Below, in the case where the object is a predetermined object, based on the second level change amount of the reflected light when the second illumination condition is added, the first illumination condition An image input device that estimates a level of reflected light when the target is the target.

  (Additional remark 2) It has an illuminating device which irradiates light to a target object, an image sensor which detects the reflected light from the said target object, and an image processing part which processes the reflected light detected by the said image sensor, The said image The processing unit is configured such that when the object is a white reference sheet, a difference between a level of the reflected light when the lighting device is turned on and a level of the reflected light when the lighting device is not turned on, and The difference between the level of the reflected light when the lighting device is lit and the level of the reflected light when the lighting device is not lit when the object is a predetermined target, and a predetermined correction value An image input device that obtains an image of the predetermined object and having no influence of the surrounding environment by calculating using.

(Supplementary Note 3) In the supplementary note 1 or the supplementary note 2, the image processing unit obtains an image of the predetermined target object and having no influence of the surrounding environment by performing the calculation of the following expression (1). The image input device described,
P (x, i) = (P (x, yr) −P (x, y)) / (P (i, ir) −P (i, i)) × (P (i, i) −Pb) + Pb ... (1)
In the above equation (1),
P (x, i): level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when there is no influence of the surrounding environment,
P (i, i): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is not lit,
P (i, ir): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is turned on,
P (x, y): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is not turned on,
P (x, yr): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is turned on,
Pb: Black level correction value when there is no illumination

(Additional remark 4) The said image processing part calculates | requires the level value P (i, y) of the reflected light from a white reference sheet when there exists an influence of surrounding environment by calculating the following (2) Formula, and after that, If there is no change in the surrounding environment, the P (i, y) is used in the following expression (3) to obtain an image of the predetermined object and having no influence of the surrounding environment. The image input device according to any one of 1 to appendix 3,
P (i, y) = (P (x, y) −Pb) × (P (i, ir) −P (i, i)) / (P (x, yr) −P (x, y)) + Pb ... (2)
P (x, i) = (P (x, y) −Pb) / (P (i, y) −Pb) × (P (i, i) −Pb) + Pb (3)
P (x, i): level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when there is no influence of the surrounding environment,
P (i, y): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when there is an influence of the surrounding environment,
P (i, i): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is not lit,
P (i, ir): Light level value on the white reference sheet when there is no shadow due to auxiliary light in addition to the illumination at the time of installation P (x, y): On the image sensor when the illumination device is not lit A level value of reflected light from the predetermined object at a predetermined pixel of
P (x, yr): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is turned on,
Pb: Black level correction value when there is no illumination

  (Supplementary note 5) The image input device according to any one of supplementary note 1 to supplementary note 4, wherein no shielding object is provided between the illumination device and the object.

  (Supplementary note 6) The image input device according to any one of supplementary note 1 to supplementary note 5, wherein the illumination device emits light including a wavelength in an infrared region.

  (Supplementary note 7) The image input device according to any one of supplementary notes 1 to 6, wherein the illumination device irradiates light including a wavelength in an ultraviolet region.

  (Additional remark 8) The said image process part calculates | requires the average value of the level value of the said reflected light about the several predetermined pixel which has the same wavelength of the spectral sensitivity which the said image sensor adjoins, and performs the said calculation using the said average value. The image input device according to any one of appendix 3 to appendix 7, which is performed.

  (Supplementary note 9) The image sensor has a structure in which each field is divided into a plurality of fields each having a plurality of strip-like pixels, and the charge stored in the pixels is transferred by switching for each field. The apparatus performs lighting or extinguishing corresponding to a field to be switched of the image sensor, and the image processing unit includes the white reference sheet in a predetermined field on the image sensor when the lighting device is lit and The level value of the reflected light from the predetermined object and the reflection from the white reference sheet and the predetermined object in a field different from the field on the image sensor when the illumination device is not lit. The image input according to any one of appendix 3 to appendix 8, wherein the calculation of the formula is performed using a light level value. Apparatus.

  (Additional remark 10) The reflected light detection step which detects the reflected light from a target object, The image processing step which acquires an image based on the reflected light detected by the said reflected light detection step, In the said image processing step, In the case where the object is a reference object under the first illumination condition, the first level change amount of the reflected light and the third illumination condition when the second illumination condition is added. In the case where the object is a predetermined object, the second level change amount of the reflected light when the second illumination condition is added is determined based on the first illumination condition. An image input method for estimating a level of reflected light when the object is the object.

(Additional remark 11) In the image input method of the image input device which has the said image sensor, an illuminating device, and the said image process part, when the said illuminating device is lighting as said 1st illumination condition, said 2nd When it is assumed that the illumination device is not lit as an illumination condition, the image processing step includes a level value of reflected light from a white reference sheet at a predetermined pixel on the image sensor when the illumination device is not lit. A level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is turned on, and a predetermined value on the image sensor when the lighting device is not turned on The level value of the reflected light from the predetermined target in the pixel of the pixel and the predetermined purpose in the predetermined pixel on the image sensor when the lighting device is turned on A step of observing the level value of the reflected light from,
An image input method comprising: calculating the following expression (4) for each reflected light level value obtained from the observed step.
P (x, i) = (P (x, yr) −P (x, y)) / (P (i, ir) −P (i, i)) × (P (i, i) −Pb) + Pb ... (4)
In the above equation (4),
P (x, i): level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when there is no influence of the surrounding environment,
P (i, i): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is not lit,
P (i, ir): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is turned on,
P (x, y): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is not turned on,
P (x, yr): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is turned on,
Pb: Black level correction value when there is no illumination

(Additional remark 12) The step which memorize | stores the level value of each reflected light calculated | required from the said observed step, and the level value P (i, y) of the reflected light from a white reference sheet when there is an influence of surrounding environment And calculating the following equation (5), and if there is no change in the surrounding environment, the P (i, y) is an image of the predetermined object using the following equation (6): The image input method according to claim 11, further comprising a step of obtaining an image that is not affected by the surrounding environment.
P (i, y) = (P (x, y) −Pb) × (P (i, ir) −P (i, i)) / (P (x, yr) −P (x, y)) + Pb ... (5)
P (x, i) = (P (x, y) −Pb) / (P (i, y) −Pb) × (P (i, i) −Pb) + Pb (6)
P (x, i): level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when there is no influence of the surrounding environment,
P (i, y): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when there is an influence of the surrounding environment,
P (i, i): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is not lit,
P (i, ir): Light level value on the white reference sheet when there is no shadow due to auxiliary light in addition to the illumination at the time of installation P (x, y): On the image sensor when the illumination device is not lit A level value of reflected light from the predetermined object at a predetermined pixel of
P (x, yr): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is turned on,
Pb: Black level correction value when there is no illumination

  The present invention is not limited to the above-described embodiment, and can be implemented with various changes and modifications without departing from the gist of the present invention.

  The disclosure of the cited patent document is incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. In addition, various combinations of various indication elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) within the scope of the claims of the present invention, Selection is possible. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea. In particular, with respect to the numerical ranges described in this document, any numerical value or small range included in the range should be construed as being specifically described even if there is no specific description.

  Furthermore, although the calculation formula appearing in the above embodiment is an example in which output is linearly output with respect to the brightness irradiated by the image sensor that is the image sensor, even if the relationship is non-linear, the non-linear The calculation can be performed by expressing the sex with a mathematical expression. That is, if it can be expressed by a value observed for the presence or absence of irradiation of the lighting device and a value that is known in advance by measurement or the like like Pb in the previous example, the influence of the surrounding environment can be removed by the lighting device. Is possible.

  INDUSTRIAL APPLICABILITY The present invention is applicable to an image input device that reduces the influence of the surrounding environment in an image input device in which the distance between the image capturing unit and the object to be imaged is large.

  This application claims the priority of the previous Japanese Patent Application No. 2013-005042 (filed on January 16, 2013), and the entire content of the previous application is incorporated herein by reference. It is considered to be. Regarding the initial description (including claims, description, drawings) of the earlier application that is the basis of the domestic priority claim, the filing date of the earlier application shall be determined as the priority date (reference date). Therefore, it should be judged that there is no effect without being affected by the added items.

DESCRIPTION OF SYMBOLS 1 Illuminating device 2 Object 3 Image pick-up part 4 Lens 5, 101 Image sensor 6 Original mounting stand 7 Stand part 10, 102 Image processing part 11 Calculation part 12 Image storage part 13 Storage part 20 Installation environment illumination 30 White reference sheet 100 Image Input device

Claims (12)

An image sensor for detecting reflected light from an object;
An image processing unit that acquires an image based on reflected light detected by the image sensor,
In the case where the object is a reference object under the first illumination condition, the image processing unit includes a first level change amount of reflected light when the second illumination condition is added,
In a case where the object is a predetermined object under a third illumination condition, a second level change amount of reflected light when the second illumination condition is added;
Based on the first illumination condition, to estimate the level of reflected light when the target is the target,
An image input apparatus characterized by that. An illumination device for irradiating the object with light;
An image sensor for detecting reflected light from the object;
An image processing unit for processing reflected light detected by the image sensor;
The image processing unit
When the object is a white reference sheet, the difference between the level of the reflected light when the lighting device is lit and the level of the reflected light when the lighting device is not lit,
A difference between a level of the reflected light when the lighting device is turned on and a level of the reflected light when the lighting device is not turned on when the object is a predetermined target;
A predetermined correction value,
An image input apparatus characterized by obtaining an image that is an image of the predetermined object and that is not affected by the surrounding environment by performing an operation using. The image input device according to claim 2, wherein the image processing unit obtains an image that is an image of the predetermined object and has no influence of the surrounding environment by performing the calculation of the following expression (1).
P (x, i) = (P (x, yr) −P (x, y)) / (P (i, ir) −P (i, i)) × (P (i, i) −Pb) + Pb ... (1)
In the above equation (1),
P (x, i): level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when there is no influence of the surrounding environment,
P (i, i): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is not lit,
P (i, ir): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is turned on,
P (x, y): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is not turned on,
P (x, yr): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is turned on,
Pb: Black level correction value when there is no illumination The image processing unit obtains the level value P (i, y) of the reflected light from the white reference sheet when there is an influence of the surrounding environment by calculating the following formula (2), and thereafter changes in the surrounding environment 3. The method according to claim 2, wherein when there is no image, the image of the predetermined object and having no influence of the surrounding environment is obtained by using the P (i, y) in the following expression (3). Image input device,
P (i, y) = (P (x, y) −Pb) × (P (i, ir) −P (i, i)) / (P (x, yr) −P (x, y)) + Pb ... (2)
P (x, i) = (P (x, y) −Pb) / (P (i, y) −Pb) × (P (i, i) −Pb) + Pb (3)
P (x, i): level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when there is no influence of the surrounding environment,
P (i, y): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when there is an influence of the surrounding environment,
P (i, i): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is not lit,
P (i, ir): Light level value on the white reference sheet when there is no shadow due to auxiliary light in addition to the illumination at the time of installation P (x, y): On the image sensor when the illumination device is not lit A level value of reflected light from the predetermined object at a predetermined pixel of
P (x, yr): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is turned on,
Pb: Black level correction value when there is no illumination   The image input device according to claim 2, wherein there is no shielding object between the illumination device and the object.   The image input device according to claim 2, wherein the illumination device irradiates light including a wavelength in an infrared region.   The image input device according to claim 2, wherein the illumination device emits light including a wavelength in an ultraviolet region.   The image processing unit obtains an average value of level values of the reflected light for a plurality of predetermined pixels having the same wavelength of spectral sensitivity adjacent to the image sensor, and performs the calculation using the average value. The image input device according to any one of claims 1 to 7. The image sensor has a structure in which each field is divided into a plurality of fields having a plurality of strip-like pixels, and the charge stored in the pixels is transferred by switching for each field,
The lighting device is turned on or off corresponding to the field to which the image sensor is switched,
The image processing unit includes a level value of reflected light from the white reference sheet and the predetermined object in a predetermined field on the image sensor when the illumination device is lit.
Using the level value of the reflected light from the white reference sheet and the predetermined object in a field different from the field on the image sensor when the lighting device is not lit,
The image input apparatus according to claim 3, wherein the calculation of the expression is performed. A reflected light detecting step for detecting reflected light from the object;
An image processing step of acquiring an image based on the reflected light detected by the reflected light detection step;
In the image processing step, when the object is a reference object under the first illumination condition, a first level change amount of the reflected light when the second illumination condition is added;
In a case where the object is a predetermined object under a third illumination condition, a second level change amount of reflected light when the second illumination condition is added;
Based on the first illumination condition, to estimate the level of reflected light when the target is the target,
An image input method characterized by the above. In an image input method of an image input device having an image sensor, an illumination device, and an image processing unit,
A level value of reflected light from a white reference sheet in a predetermined pixel on the image sensor when the lighting device is not lit;
A level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the illumination device is lit;
A level value of reflected light from a predetermined object in a predetermined pixel on the image sensor when the lighting device is not lit;
A level value of reflected light from the predetermined object in a predetermined pixel on the image sensor when the lighting device is turned on; and
A step of observing
A step of calculating the following equation (4) for each reflected light level value obtained from the observed step;
An image input method comprising:
P (x, i) = (P (x, yr) −P (x, y)) / (P (i, ir) −P (i, i)) × (P (i, i) −Pb) + Pb ... (4)
In the above equation (4),
P (x, i): level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when there is no influence of the surrounding environment,
P (i, i): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is not lit,
P (i, ir): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is turned on,
P (x, y): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is not turned on,
P (x, yr): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is turned on,
Pb: Black level correction value when there is no illumination Storing a level value of each reflected light obtained from the observed step;
Obtaining the level value P (i, y) of the reflected light from the white reference sheet when there is an influence of the surrounding environment by calculating the following equation (5);
If there is no change in the surrounding environment, using the P (i, y) in the following equation (6) to obtain an image of the predetermined object and having no influence of the surrounding environment;
The image input method according to claim 11, further comprising:
P (i, y) = (P (x, y) −Pb) × (P (i, ir) −P (i, i)) / (P (x, yr) −P (x, y)) + Pb ... (5)
P (x, i) = (P (x, y) −Pb) / (P (i, y) −Pb) × (P (i, i) −Pb) + Pb (6)
P (x, i): level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when there is no influence of the surrounding environment,
P (i, y): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when there is an influence of the surrounding environment,
P (i, i): a level value of reflected light from the white reference sheet at a predetermined pixel on the image sensor when the lighting device is not lit,
P (i, ir): Light level value on the white reference sheet when there is no shadow due to auxiliary light in addition to the illumination at the time of installation P (x, y): On the image sensor when the illumination device is not lit A level value of reflected light from the predetermined object at a predetermined pixel of
P (x, yr): a level value of reflected light from the predetermined object at a predetermined pixel on the image sensor when the lighting device is turned on,
Pb: Black level correction value when there is no illumination

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