JP6838348B2 - Image reader and image reading method - Google Patents

Description

The present technology relates to an image reading device and an image reading method for generating image information from a reading target.

An image reading device that optically reads image information from an arbitrary reading target is widely used. Such an image reader is often implemented as part of an image forming apparatus such as a copier, a facsimile, or a multifunction device.

As one of the typical configurations in which the image reader optically reads the image information from the reading target, a configuration using a line sensor is adopted.

As an example, an image reader has been proposed in which a document is conveyed and its surface is read by a CIS (Contact Image Sensor). In this type of image reading device, the document is conveyed to the CIS fixed to the image reading device, and the document is read (scanned) by the CIS.

In order to correct the image in reading the CIS, a shading plate (opposing plate) is provided so as to face the CIS.

Here, the shading plate is an image caused by non-uniform illuminance when a light source that irradiates light toward a document is turned on, or non-uniform sensitivity of an image sensor that receives light reflected by the document. It is a white plate used as a reference for the density level of an image to correct the unevenness of the density level (shading correction).

However, since the shading plate is provided in the document transport path where paper dust and the like are likely to fly, deposits (dust) are likely to adhere.

If deposits (dust) such as paper dust and toner adhere to the shading board, the CIS reading result will be low, and the shading correction will work to brighten the same pixels, resulting in white streaks in the output image. There is a possibility that it will end up.

In order to prevent this white streak, in Japanese Patent Application Laid-Open No. 2008-187531, dust is detected and removed from the difference between the initial shading data before dust adhesion and the shading data before scanning the original, which are held in advance. A method has been proposed.

Japanese Unexamined Patent Publication No. 2008-187531

However, in the above method, a memory for holding the initial data is required, and when compared with the initial value, it is not possible to cope with the level fluctuation due to the change of CIS with time, and the detection accuracy of the deposit is improved. May decrease.

The present technology has been made to solve the above problems, and provides an image reading device and an image reading method capable of detecting deposits with high accuracy with a simple configuration.

An image reading device according to a certain aspect includes a white member, a reading unit that reads an image by condensing the reflected light reflected from the white member or the original with a lens, and an image processing unit that executes shading correction. The image processing unit includes an acquisition unit that acquires shading data of the white member read by the reading unit, an approximation formula calculation unit that calculates an approximation formula of shading data based on the shading data acquired by the acquisition unit, and an approximation formula calculation unit. Includes the approximate expression calculated in 1 and the determination unit for detecting deposits based on the shading data.

Preferably, the approximate expression calculation unit includes a polarization point detection unit that detects a plurality of polarization points of the shading data, and a periodic amplitude calculation unit that calculates the period and amplitude based on the plurality of polarization points detected by the polarization point detection unit. And a sine wave calculation unit that calculates an approximate expression of a sine wave based on the calculation result of the periodic amplitude calculation unit.

Preferably, the depolarizing point detecting unit detects the pixels and the gradation of the plurality of depolarizing points, respectively, and the periodic amplitude calculating unit calculates the period based on the distance between the adjacent pixels of the plurality of depolarizing points, and a plurality of. The amplitude is calculated based on the gradation difference between the peak gradation and the bottom gradation of the pole change point.

Preferably, the periodic amplitude calculation unit calculates the period by excluding the variable poles when the distance between the adjacent pixels is equal to or larger than a predetermined value among the plurality of variable poles.

Preferably, the periodic amplitude calculation unit calculates the amplitude by excluding the poles when there is a pole whose gradation difference between the peak gradation and the bottom gradation is equal to or more than a predetermined value among the plurality of poles. To do.

Preferably, the sine wave calculation unit calculates an approximate expression of the sine wave by adding the intermediate values between the peak gradation and the bottom gradation of the plurality of poles.

Preferably, the image processing unit further includes an area setting unit that sets a range in which deposits are detected based on the detection result of the determination unit.

Preferably, the area setting unit sets the range between the poles having a peak gradation adjacent to the pole where the deposit is detected to the range where the deposit is detected.

Preferably, the area setting unit determines whether or not the poles having adjacent peak gradations are the poles having continuous peak gradations, and between the poles having continuous peak gradations. Set the range of to the range where deposits are detected.

An image reading method according to a certain aspect, in which a step of acquiring shading data by condensing the reflected light reflected from a white member with a lens and a step of calculating an approximate expression of shading data based on the acquired shading data. And a step of detecting deposits based on the calculated approximate expression and the shading data.

It is a schematic diagram which shows the appearance configuration example of the image forming apparatus which includes the image reading apparatus according to Embodiment 1. FIG. It is a schematic diagram which shows the cross-sectional configuration example of the image reading apparatus 4 according to Embodiment 1. It is a figure explaining the outline of the shading correction based on Embodiment 1. It is a block diagram explaining the functional structure of the image reading apparatus 4 based on Embodiment 1. It is a flow figure explaining the determination process of the deposit in the image processing unit 100 based on Embodiment 1. It is a figure explaining the calculation of the approximate expression of shading data based on Embodiment 1. It is a figure explaining the detection of dust based on Embodiment 1. It is a block diagram explaining the functional structure of the image reading apparatus 4 based on Embodiment 2. It is a figure explaining the expansion method of the area expansion part 112 based on Embodiment 2. It is a figure explaining the specific example (the 1) of the waste determination area based on Embodiment 2. It is a figure explaining the specific example (the 2) of the garbage determination area based on Embodiment 2.

Embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

(Embodiment 1)
<A. Device configuration>
Next, an apparatus configuration of an image reader and an image forming apparatus including the image reader according to the first embodiment will be described. Hereinafter, as a typical example, an image forming apparatus 1 mounted as a multi-function peripheral (MFP) including an image reading apparatus will be described. The present invention is not particularly limited to this, and the image reading device may be mounted as a copying machine or a facsimile including an image reading device, or the image reading device may be mounted as a single device.

(A1: Image forming apparatus)
FIG. 1 is a schematic view showing an example of external configuration of an image forming apparatus including an image reading apparatus according to the first embodiment.

With reference to FIG. 1, the image forming apparatus 1 according to the first embodiment has a plurality of functions such as a copy function, a scanner function, a printer function, and a fax function, and is a network such as a LAN (Local Area Network) or a telephone line. Data can be sent and received via. That is, the image forming apparatus 1 can output the image information (image data) read from the reading target to another computer via the network as a scanner function or a copy function, and can output the image information (image data) read from the reading target to another computer via the network, and as a printer function or a fax function, via the network. Image information (image data) can be acquired from another computer, and printing or FAX transmission based on the image data can be performed.

When the image reader is mounted on the image forming apparatus, any method may be adopted for the image forming portion (print engine) of the image forming apparatus. For example, an electrophotographic method (monochrome method or color method), an inkjet method, a heat-sensitive method, a heat transfer method, and the like can be mentioned. FIG. 1 shows an image forming apparatus 1 adopting an electrophotographic method as a typical example.

The image forming apparatus 1 includes an image forming unit 5, a paper feeding unit 6 arranged below the image forming unit 5, and an image reading device 4 arranged above the image forming unit 5.

The image reading device 4 reads image information from a scanning target and outputs image data or the like, and mainly includes a reading main body unit 2 and an automatic document transporting unit 3. The user can also arrange one original directly on the scanning main body 2 to read the image information, or arrange one or more originals on the automatic document conveying unit 3 to continuously read the image information. It can also be read. In this continuous scanning operation, the scanning main body 2 and the automatic document transporting unit 3 operate in synchronization with each other to transport the documents arranged in the automatic document transporting unit 3 one by one toward the scanning main body 2. , The scanning main body 2 reads image information when the document passes a predetermined position and generates image data.

The paper feeding unit 6 stores paper, which is a recording medium, and supplies the stored recording media to the image forming unit 5 one by one in correspondence with the image forming operation in the image forming unit 5.

The image forming unit 5 outputs an image on the recording medium supplied from the paper feeding unit 6 based on the image data read by the image reading device 4, the image data acquired via the network, the directly input image data, and the like. Form. In this way, the image forming unit 5 prints arbitrary image data on the recording medium. As one typical example, the image forming unit 5 forms an image based on the image information read by the image reading device 4. The recording medium on which the image is formed by the image forming unit 5 is output to the paper ejection unit 7 between the image forming unit 5 and the reading main body unit 2.

An operation panel 8 having a plurality of keys or buttons is provided on the front side (the side operated by the user) of the image forming apparatus 1. The operation panel 8 receives an operation instruction from the user and outputs the received operation instruction to the image forming unit 5 or the like.

(A2: Image reader)
Next, the device configuration of the image reading device 4 shown in FIG. 1 will be described in more detail.

FIG. 2 is a schematic view showing a cross-sectional configuration example of the image reading device 4 according to the first embodiment.
In the configuration example of the image reading device 4 shown in FIG. 2, image information can be read from both sides of the document. Specifically, the automatic document transport unit 3 has a paper feed tray 31 on which one or a plurality of documents 70 are arranged. The documents 70 arranged in the paper feed tray 31 are sent out one by one from the top layer to the document transport path 30 by the pickup roller 32 and the paper feed roller pair 33. In the document transport path 30, the document 70 is transported to the resist roller pair 35 by the intermediate roller pair 34. The resist roller pair 35 functions as a skew correction roller, corrects the conveyed document 70 to its original posture, and feeds the document 70 toward the first transfer roller pair 36 at a predetermined timing. The document 70 is sent out onto the slit glass 21 which is the transport reading surface of the reading main body 2 by the first transport roller pair 36, and passes over the slit glass 21 by the reading roller 42.

When the document 70 passes over the slit glass 21, the first reading unit 22 located below the slit glass 21 reads the image information of the downward surface (front surface) of the document 70.

A second transport roller pair 37, a second reading unit 38, a third transport roller pair 39, and a paper ejection roller 40 are arranged on the transport downstream side of the slit glass 21 of the document transport path 30. The document 70 that has passed over the slit glass 21 is sent out to just below the second reading unit 38 by the second transport roller pair 37. When the document 70 passes directly under the second reading unit 38, the image information of the upward surface (back surface) of the document 70 is read.

The document 70 that has passed directly under the second reading unit 38 is ejected onto the paper ejection tray 41 by the third transport roller pair 39 and the paper ejection roller 40.

A slit glass 21 and a platen glass 23 are provided on the upper surface of the reading main body 2. The first reading unit 22 is arranged inside the reading main body unit 2. The first reading unit 22 is used to read the image information of the surface of the document 70 passing over the slit glass 21 and / or the image information of the document 70 arranged on the platen glass 23. When reading the image information of the document 70 passing over the slit glass 21, the scanning unit 24 and the traveling unit 25 are placed in a fixed state. On the other hand, when reading the image information of the document 70 arranged on the platen glass 23, the scanning unit 24 and the traveling unit 25 move in the sub-scanning direction Y, so that the range read by the first reading unit 22 is sequentially changed. To do.

The scanning unit 24 and the traveling unit 25 are supported by a pair of support rails 46 arranged in the reading main body 2, and slide and move by the power of an actuator (not shown).

The second reading unit 38 is fixedly arranged in the automatic document transporting unit 3. Further, the shading plate 43 is fixedly arranged so as to face the second reading unit 38. The shading plate 43 has a function as a white reference body for shading correction.

The first reading unit 22 and the second reading unit 38 include light sources 50 and 52 for irradiating light toward the surface of the document to be read, and line sensors 51 for receiving the reflected light generated by the reading target. Includes 53 and. The line sensors 51 and 53 are composed of a plurality of photoelectric conversion elements arranged along the main scanning direction, and output an output value according to the brightness (light intensity) of the incident reflected light. That is, the line sensor converts the optically reflected image generated in the reading target into an electrical image signal and outputs it.

In the image reading device 4 according to the present embodiment, CIS is used as a line sensor of at least one of the first reading unit 22 and the second reading unit 38. In particular, the 1-line CIS reading method is adopted for the first reading unit 22 and / or the second reading unit 38.

It is not necessary to adopt the 1-line CIS reading method for both the first reading unit 22 and the second reading unit 38, and the 1-line CIS reading method may be adopted for only one of them, or the image reading may be performed. The device 4 may employ only one of the first reading unit 22 and the second reading unit 38.

<B. Shading correction>
FIG. 3 is a diagram illustrating an outline of shading correction based on the first embodiment.

As shown in FIG. 3, the line sensor 53 is a linear image sensor in which a plurality of light receiving pixels are arranged in a row. The line sensor 53 photoelectrically converts the reflected light from the shading plate 43 or the document 70 and outputs an RGB analog signal.

The shading plate 43 is a reference member, and a white plate brighter than the original is used. The line sensor 53 corresponds to a reference document for adjusting the white gradation level.

Here, the line sensor 53 has a self-focused lens array (SLA) that collects the reflected light. Since the image read by the Selfock lens array becomes a cyclically wavy sinusoidal image, it is necessary to perform shading correction to correct the image to a constant gradation, and therefore it is necessary to acquire shading data. is there.

FIG. 3A shows a case where dust such as paper dust is attached to the shading plate 43 as deposits. In this case, a value in which the shading data is lower than the assumed gradation is detected for the pixel to which the deposit is attached. That is, it is judged to be dark.

As a result, in the shading correction, a correction for brightening the pixel is executed.
FIG. 3B shows a case where shading correction is executed on the original 70 based on the shading data. In this case, a specific pixel portion determined to be dark by the shading correction is corrected to be bright. As a result, white vertical stripes are generated in the reading result of the document 70.

Therefore, it is necessary to remove the influence of the deposits adhering to the shading plate 43.
FIG. 4 is a block diagram illustrating a functional configuration of the image reading device 4 based on the first embodiment.

As shown in FIG. 4, the image reading device 4 based on the first embodiment includes an image processing unit 100.

The image processing unit 100 includes a data acquisition unit 103, a data holding unit 104, a determination unit 101, a shading data interpolation unit 200, a shading data holding unit 201, and a shading correction unit 202.

The data acquisition unit 103 is composed of an AFE (analog front end) that A / D-converts an analog signal from the line sensor 53 into a digital signal.

The data holding unit 104 temporarily holds the shading data acquired by the data acquisition unit 103.

The determination unit 101 executes the determination process of the adhered matter (dust) based on the shading data held by the data holding unit 104.

The shading data interpolation unit 200 executes an interpolation process for removing deposits (dust) from the shading data.

The shading data holding unit 201 holds the interpolation processing result of the shading data interpolation unit 200.

The shading correction unit 202 executes a shading correction process for correcting unevenness of the original data based on the shading data held by the shading data holding unit 201 with respect to the data acquired by the data acquisition unit 103.

The determination unit 101 includes an approximation formula calculation unit 102 and a dust detection unit 110.
The approximation formula calculation unit 102 calculates an approximation formula for shading data based on the shading data held by the data holding unit 104.

The dust detection unit 110 detects deposits (dust) based on the shading data held by the data holding unit 104 and the approximate formula calculated by the approximate formula calculation unit 102.

The approximate expression calculation unit 102 includes a peak pixel detection unit 105, a bottom pixel detection unit 106, a dynamic range calculation unit 107, a period calculation unit 108, and a calculation unit 109.

The peak pixel detection unit 105 detects a pixel having a peak gradation among a plurality of poles of shading data.

The bottom pixel detection unit 106 detects a pixel having a bottom gradation among a plurality of poles of shading data.

In this example, a configuration in which the peak pixel detection unit 105 and the bottom pixel detection unit 106 are provided separately will be described, but the present invention is not particularly limited to this, and a configuration in which a pole change point is detected as a unit is also possible. Is.

The period calculation unit 108 calculates the period of the approximate expression of the sine wave of the shading data based on the distance between the pixels having the peak gradation.

The dynamic range calculation unit 107 calculates the amplitude of the approximate expression of the sine wave of the shading data based on the gradation difference between the peak gradation and the bottom gradation.

In this example, a configuration in which the period calculation unit 108 and the dynamic range calculation unit 107 are provided separately will be described, but the configuration is not particularly limited to this, and the period and amplitude can be calculated integrally. Is.

The calculation unit 109 calculates an approximate expression of a sine wave of shading data based on the period calculated by the period calculation unit 108 and the amplitude calculated by the dynamic range calculation unit 107.

FIG. 5 is a flow chart illustrating a process of determining deposits in the image processing unit 100 based on the first embodiment.

As shown in FIG. 5, first, the image processing unit 100 acquires shading data (step S2). Specifically, the data acquisition unit 103 acquires the shading data detected by the line sensor 53.

Next, the image processing unit 100 calculates an approximate expression for shading data (step S4). Specifically, the approximate expression calculation unit 102 calculates an approximate expression for shading data.

Next, the image processing unit 100 executes the comparison process (step S6). Specifically, the dust detection unit 110 executes a comparison process between the acquired shading data and the approximate expression calculated by the approximate expression calculation unit 102.

Next, the image processing unit 100 determines whether or not there is an abnormal value (step S8). Specifically, the dust detection unit 110 determines whether or not there is an abnormal value based on the comparison processing result.

In step S8, when the image processing unit 100 determines that there is an abnormal value (YES in step S8), it determines that there is dust (step S10). Specifically, when the dust detection unit 110 determines that there is an abnormal value based on the comparison processing result, it determines that there is dust.

Then, the process ends (end).
On the other hand, in step S8, when the image processing unit 100 determines that there is no abnormal value (NO in step S8), it determines that there is no dust (step S12). Specifically, when the dust detection unit 110 determines that there is no abnormal value based on the comparison processing result, it determines that there is dust.

Then, the process ends (end).
FIG. 6 is a diagram illustrating calculation of an approximate expression of shading data based on the first embodiment.

As shown in FIG. 6, the shading data acquired by the data acquisition unit is shown. Here, what is indicated by a white circle is what was detected as a pole.

With respect to the plurality of poles detected in the shading data, the peak pixel detection unit 105 detects the pixels of the poles with high gradation as peak pixels. Further, the bottom pixel detection unit 106 detects a pixel at a pole of a low gradation as a bottom pixel.

The period calculation unit 108 calculates the period T of the sine wave based on the distance between adjacent peak pixels among the plurality of peak pixels detected by the peak pixel detection unit 105. The period calculation unit 108 calculates the period T by excluding the peak pixels that are singular points from the plurality of peak pixels. Specifically, the period T may be calculated by excluding the peak pixels in which the distance between the peak pixels is equal to or greater than a predetermined value.

The dynamic range calculation unit 107 calculates the amplitude H of the sine wave based on the gradation difference between the peak pixel and the bottom pixel. The dynamic range calculation unit 107 calculates the amplitude H by excluding the peak pixel and the bottom pixel, which are singular points, from the peak pixel and the bottom pixel. Specifically, the amplitude H may be calculated by excluding the peak pixel in which the peak pixel is equal to or more than a predetermined value or the bottom pixel in which the bottom pixel is equal to or less than a predetermined value.

The calculation unit 109 calculates an approximate expression for a sine wave based on the calculated period T and amplitude H. The intermediate value between the gradation values of the peak pixel and the bottom pixel is calculated as the offset value z.

As a general formula, it is calculated as the following approximate formula.
y = Hsin2πx / T + z
y is the gradation value and x is the pixel position.

FIG. 7 is a diagram illustrating the detection of dust based on the first embodiment.
As shown in FIG. 7, the shading data acquired by the data acquisition unit and the approximate expression are shown.

In addition, the difference data between the shading data and the approximate expression is also shown.
The left vertical axis represents the gradation value, and the right vertical axis indicates the difference value.

In this example, the case where the difference value is set to ± 5 is shown as the threshold value.
In this example, a region where the difference value exceeds ± 5 is shown in the range surrounded by the dotted line, and since there is a value exceeding the threshold value, it is determined that there is dust.

In the first embodiment, an approximate expression is calculated based on the acquired shading data. Then, based on the comparison between the calculated approximate expression and the acquired shading data, if there is a value exceeding the threshold value, it is determined that there is deposit (dust). On the other hand, if the threshold value is not exceeded, it is determined that there is no deposit (dust).

Therefore, it is not necessary to acquire shading data (initial data) in advance and store it in the memory, and it is possible to detect deposits with a simple configuration. Further, since the determination of the presence or absence of deposits (dust) is executed based on the shading data including the amount of change with time of CIS, highly accurate detection is possible.

(Embodiment 2)
In the second embodiment, a method of setting a range determined to have deposits (dust) will be described.

FIG. 8 is a block diagram illustrating a functional configuration of the image reading device 4 based on the second embodiment.
As shown in FIG. 8, the image reading device 4 based on the second embodiment includes an image processing unit 100 #.

The image processing unit 100 # is different from the image processing unit 100 described with reference to FIG. 4 in that the determination unit 101 is replaced with the determination unit 101 #. The determination unit 101 # is different from the determination unit 101 in that the area expansion unit 112 is further added. Since the other configurations are the same as those described in FIG. 4, the detailed description thereof will not be repeated.

The area expansion unit 112 expands and sets the area determined to have deposits (dust). Specifically, the area expansion unit 112 expands the area to the range between the peak pixels adjacent to the points determined to be deposits (dust).

FIG. 9 is a diagram illustrating an expansion method of the area expansion unit 112 based on the second embodiment.
As shown in FIG. 9, an approximate expression is calculated based on the acquired shading data, and it is determined whether or not the threshold value is exceeded based on the comparison between the calculated approximate expression and the acquired shading data.

In this example, it is determined that the threshold value is exceeded in the region of the alternate long and short dash line, that is, there is deposit (dust).

The area expansion unit 112 expands to the adjacent peak pixels with respect to the region determined to have the deposit (dust) (the region where the thick line rises).

By this method, the area to be shading-corrected is expanded. If shading correction is performed only on the area where it is determined that there is dust, there is a possibility that discontinuous parts may occur in the correction data. Streaks may occur at the discontinuity.

In the second embodiment, it is possible to suppress the appearance of discontinuous portions of the correction data by expanding the region determined to have dust (also referred to as a dust determination region) to a certain range between the peak pixels. This makes it possible to suppress the occurrence of streaks.

FIG. 10 is a diagram illustrating a specific example (No. 1) of the waste determination area based on the second embodiment.
FIG. 10 shows a case where a plurality of dusts are attached to the shading plate 43.

As shown in FIG. 10A, it is determined that there is dust based on the comparison between the approximate expression (solid line) and the shading data line (dotted line). In this example, it is determined that there is dust at a plurality of points.

The area expansion unit 112 sets the area between the peak pixels adjacent to the point where it is determined that there is dust in the dust determination area.

The same applies to FIG. 10 (B).
FIG. 11 is a diagram illustrating a specific example (No. 2) of the waste determination area based on the second embodiment.

FIG. 11 shows a case where a wide range of dust is attached to the shading plate 43.

As shown in FIG. 11A, it is determined that there is dust based on the comparison between the approximate expression (solid line) and the shading data line (dotted line). In this example, it is determined that there is dust in a wide range.

The area expansion unit 112 sets the area between the peak pixels adjacent to the point where it is determined that there is dust in the dust determination area.

The same applies to FIGS. 11 (B) and 11 (C).
The area expansion unit 112 determines whether or not the peak pixel is a continuous peak pixel, and if it is determined that the peak pixel is a continuous peak pixel, the area between the peak pixels may be set in the dust determination area. good.

Specifically, when the gradation value of adjacent peak pixels is low (peak value B) as shown in FIG. 11B, the adjacent peak pixels are continuous peak pixels (peak value A). Whether or not it is determined, and the area between the continuous peak pixels (peak value A) is set as the dust determination area.

Although the embodiments based on the present invention have been described above, the embodiments disclosed this time are exemplary in all respects and are not restrictive. The technical scope of the present invention is indicated by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

1 Image forming device, 2 Main body, 3 Automatic document transporting section, 4 Image reading device, 5 Image forming section, 6 Feeding section, 7 Paper ejection section, 8 Operation panel, 21 Slit glass, 22 First reading section, 23 Platen glass, 24 scanning unit, 25 traveling unit, 30 document transport path, 31 paper feed tray, 32 pickup roller, 33 paper feed roller pair, 34 intermediate roller pair, 35 resist roller pair, 36 first transport roller pair, 37th 2 transport roller pair, 38 second reader pair, 39 third transport roller pair, 40 paper ejection roller, 41 paper ejection tray, 42 reader roller, 43 shading plate, 46 support rail, 50, 52 light source, 51, 53 line sensor , 70 manuscript, 100 image processing unit, 101 judgment unit, 102 approximation formula calculation unit, 103 data acquisition unit, 104 data retention unit, 105 peak pixel detection unit, 106 bottom pixel detection unit, 107 dynamic range calculation unit, 108 cycle calculation Unit, 109 calculation unit, 110 dust detection unit, 112 area expansion unit, 200 shading data interpolation unit, 201 shading data holding unit, 202 shading correction unit.

Claims (9)

White members and
A reading unit that reads an image by condensing the reflected light reflected from the white member or the original with a lens.
Equipped with an image processing unit that executes shading correction
The image processing unit
An acquisition unit that acquires shading data of the white member read by the reading unit, and
An approximation formula calculation unit that calculates an approximation formula for the shading data based on the shading data acquired by the acquisition unit, and an approximation formula calculation unit.
Includes an approximation formula calculated by the approximation formula calculation unit and a determination unit for detecting deposits adhering to the white member based on the shading data.
The approximate expression calculation unit
A depolarizing point detection unit that detects a plurality of depolarizing points of the shading data, and
A periodic amplitude calculation unit that calculates the period and amplitude based on a plurality of depolarization points detected by the depolarization point detection unit, and a periodic amplitude calculation unit.
Including a sine wave calculation unit that calculates an approximate expression of a sine wave based on the calculation result of the periodic amplitude calculation unit.
The depolarizing point detection unit detects pixels and gradations of the plurality of depolarizing points, respectively.
The periodic amplitude calculation unit
The period is calculated based on the distance between adjacent pixels of the plurality of poles.
The amplitude is calculated based on the gradation difference between the peak gradation and the bottom gradation of the plurality of poles.
In the calculation of the period, it calculates the period excluding the inflection point in the case where the distance between pixels adjacent in the plurality of inflection point is the inflection point to be a predetermined value or more, images reader. White members and
A reading unit that reads an image by condensing the reflected light reflected from the white member or the original with a lens.
Equipped with an image processing unit that executes shading correction
The image processing unit
An acquisition unit that acquires shading data of the white member read by the reading unit, and
An approximation formula calculation unit that calculates an approximation formula for the shading data based on the shading data acquired by the acquisition unit, and an approximation formula calculation unit.
Includes an approximation formula calculated by the approximation formula calculation unit and a determination unit for detecting deposits adhering to the white member based on the shading data.
The approximate expression calculation unit
A depolarizing point detection unit that detects a plurality of depolarizing points of the shading data, and
A periodic amplitude calculation unit that calculates the period and amplitude based on a plurality of depolarization points detected by the depolarization point detection unit, and a periodic amplitude calculation unit.
Including a sine wave calculation unit that calculates an approximate expression of a sine wave based on the calculation result of the periodic amplitude calculation unit.
The depolarizing point detection unit detects pixels and gradations of the plurality of depolarizing points, respectively.
The periodic amplitude calculation unit
The period is calculated based on the distance between adjacent pixels of the plurality of poles.
The amplitude is calculated based on the gradation difference between the peak gradation and the bottom gradation of the plurality of poles.
In the calculation of the amplitude, if there is a pole that has a gradation difference between the peak gradation and the bottom gradation of a predetermined value or more among the plurality of poles, the pole is excluded and the amplitude is calculated. , images reader. The image reading according to claim 1 or 2, wherein the sine wave calculation unit calculates an approximate expression of the sine wave by adding an intermediate value between the peak gradation and the bottom gradation of the plurality of poles. apparatus. The image reading device according to claim 1 or 2, wherein the image processing unit further includes an area setting unit that sets a range in which the deposit is detected based on the detection result of the determination unit. The image reading device according to claim 4, wherein the area setting unit sets a range between the poles having a peak gradation adjacent to the pole where the deposit is detected to a range where the deposit is detected. White members and
A reading unit that reads an image by condensing the reflected light reflected from the white member or the original with a lens.
Equipped with an image processing unit that executes shading correction
The image processing unit
An acquisition unit that acquires shading data of the white member read by the reading unit, and
An approximation formula calculation unit that calculates an approximation formula for the shading data based on the shading data acquired by the acquisition unit, and an approximation formula calculation unit.
An approximation unit calculated by the approximation formula calculation unit, a determination unit for detecting deposits adhering to the white member based on the shading data, and a determination unit.
Including an area setting unit that sets a range in which the deposit is detected based on the detection result of the determination unit.
The area setting unit
The range between the poles having a peak gradation adjacent to the pole where the deposit was detected was set to the range where the deposit was detected.
It is determined whether or not the poles having adjacent peak gradations are poles having continuous peak gradations.
To set the range between inflection point having a peak tone with the continuity of the range of detection the deposits, the image reading apparatus. The step of acquiring shading data by condensing the reflected light reflected from the white member with a lens, and
A step of calculating an approximate expression of the shading data based on the acquired shading data, and
A step of detecting deposits adhering to the white member based on the calculated approximate expression and the shading data is provided.
The step of calculating the approximate expression of the shading data is
A step of detecting a plurality of poles of the shading data and
Steps to calculate the period and amplitude based on the multiple poles detected, and
Including the step of calculating the approximate expression of the sine wave based on the calculation result of the period and the amplitude.
In the step of detecting a plurality of poles of the shading data, the pixels and gradations of the plurality of poles are detected, respectively.
The step of calculating the period and amplitude based on the plurality of detected poles is
A step of calculating a period based on the distance between adjacent pixels of the plurality of poles, and a step of calculating the period.
Including the step of calculating the amplitude based on the gradation difference between the peak gradation and the bottom gradation of the plurality of poles.
The step of calculating the period based on the distance between the adjacent pixels of the plurality of poles is the change when there is a pole in which the distance between the adjacent pixels of the plurality of poles is equal to or greater than a predetermined value. An image reading method for calculating the period by excluding extreme points. The step of acquiring shading data by condensing the reflected light reflected from the white member with a lens, and
A step of calculating an approximate expression of the shading data based on the acquired shading data, and
A step of detecting deposits adhering to the white member based on the calculated approximate expression and the shading data is provided.
The step of calculating the approximate expression of the shading data is
A step of detecting a plurality of poles of the shading data and
Steps to calculate the period and amplitude based on the multiple poles detected, and
Including the step of calculating the approximate expression of the sine wave based on the calculation result of the period and the amplitude.
In the step of detecting a plurality of poles of the shading data, the pixels and gradations of the plurality of poles are detected, respectively.
The step of calculating the period and amplitude based on the plurality of detected poles is
A step of calculating a period based on the distance between adjacent pixels of the plurality of poles, and a step of calculating the period.
Including the step of calculating the amplitude based on the gradation difference between the peak gradation and the bottom gradation of the plurality of poles.
In the step of calculating the amplitude based on the gradation difference between the peak gradation and the bottom gradation of the plurality of poles, the gradation difference between the peak gradation and the bottom gradation among the plurality of poles is a predetermined value. An image reading method for calculating the amplitude by excluding the poles when there is a pole that becomes the above. The step of acquiring shading data by condensing the reflected light reflected from the white member with a lens, and
A step of calculating an approximate expression of the shading data based on the acquired shading data, and
A step of detecting deposits adhering to the white member based on the calculated approximate expression and the shading data, and a step of detecting the deposits.
A step of setting a range in which the deposit is detected based on the detection result of the deposit is provided.
The step of setting the range in which the deposit is detected is
A step of setting the range between the poles having a peak gradation adjacent to the pole where the deposit was detected to the range where the deposit was detected, and
A step of determining whether or not the pole having an adjacent peak gradation is a pole having a continuous peak gradation, and a step of determining whether or not the pole has a continuous peak gradation.
An image reading method including a step of setting a range between poles having continuous peak gradation to a range in which deposits are detected.