JP2021093717A - Image data processing apparatus, image reading device, image forming apparatus, and image data processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate visible light reading data from visible light + invisible light reading data while suppressing a change in the level of image data and deterioration of color reproducibility. SOLUTION: A first wavelength image data is acquired from both reflected light of a first wavelength light and a second wavelength light emitted from a light source and incident on a first image sensor. The first offset component removing unit that removes the first offset component contained in the wavelength image data to generate the first image data, and the light of the second wavelength that is irradiated from the light source and incident on the second image sensor. The second offset component removing unit that acquires the second wavelength image data from the reflected light of the above, removes the second offset component contained in the second wavelength image data, and generates the second image data, and the first A second image data component removal that is provided after the offset component removing section and the second offset component removing section of the above and removes the second image data from the first image data to generate the third image data. It is provided with a processing unit. [Selection diagram] FIG. 8

Description

The present invention relates to an image data processing device, an image reading device, an image forming device, and an image data processing method.

Conventionally, there is already known a technique of irradiating a subject with visible light and invisible light at the same time to read an image and obtaining invisible light image data or visible light image data from the obtained read data.

For example, Patent Document 1 discloses a technique for removing an infrared wavelength component from a visible wavelength component including an infrared wavelength component without using an optical infrared cut filter. More specifically, according to the technique disclosed in Patent Document 1, in order to obtain a visible wavelength component, an infrared + visible wavelength component is detected by a visible component image sensor, and at the same time, an infrared wavelength component is detected by an infrared component image sensor. Is detected. Then, according to the technique disclosed in Patent Document 1, only the visible wavelength component is extracted by removing the infrared wavelength component from the infrared + visible wavelength component before the shading correction processing by utilizing these detection results. ..

However, according to the conventional technique, the infrared + visible wavelength component is detected by the visible component image sensor, and at the same time, the infrared wavelength component is detected by the infrared component image sensor, and the infrared wavelength component is detected from the infrared + visible wavelength component. Is a method of directly removing. That is, it is affected by the offset component (component other than the regular reading information) included in each image sensor output information, and even a part of the visible wavelength component is removed, and as a result, the data level of the visible light image changes (monochrome image). There was a problem that the color reproducibility was deteriorated (color image).

The present invention has been made in view of the above, and an object of the present invention is to suppress changes in the level of image data and deterioration of color reproducibility, and to generate visible light reading data from visible light + invisible light reading data. ..

In order to solve the above-mentioned problems and achieve the object, the present invention presents the reflected light of both the first wavelength light and the second wavelength light emitted from the light source and incident on the first image sensor. The first offset component removing unit that acquires the first wavelength image data from the data, removes the first offset component contained in the first wavelength image data, and generates the first image data, and irradiates from the light source. Then, the second wavelength image data is acquired from the reflected light of the light of the second wavelength incident on the second image sensor, and the second offset component contained in the second wavelength image data is removed. A second offset component removing section for generating the second image data, a second offset component removing section, and the second offset component removing section are provided after the first offset component removing section, and the second offset component removing section is provided from the first image data. It is characterized by including a second image data component removing processing unit that removes the image data of the above and generates a third image data.

According to the present invention, it is possible to suppress changes in image data and deterioration of color reproducibility, and to generate visible light reading data from visible light + invisible light reading data.

FIG. 1 is a diagram showing a configuration of an example of an image processing device according to the first embodiment. FIG. 2 is a cross-sectional view illustrating the structure of the image reading unit as an example. FIG. 3 is a block diagram showing an optical connection of each part constituting the image reading unit according to the first embodiment. FIG. 4 is a diagram showing a flow of processing according to the first embodiment. FIG. 5 is a diagram schematically showing an image reading example of the second embodiment. FIG. 6 is a diagram schematically showing an image reading example of the second embodiment. FIG. 7 is a block diagram showing an optical connection of each part constituting the image reading unit according to the second embodiment. FIG. 8 is a diagram showing a flow of processing according to the second embodiment. FIG. 9 is a diagram schematically showing an image reading example of the third embodiment. FIG. 10 is a diagram schematically showing an image reading example of the third embodiment. FIG. 11 is a diagram showing an example of the spectral sensitivity characteristic of the image sensor. FIG. 12 is a diagram showing an example of the spectral sensitivity characteristic (luminous efficiency characteristic) of the human eye. FIG. 13 is a diagram schematically showing an image reading example of the fourth embodiment. FIG. 14 is a diagram schematically showing an image reading example of the fourth embodiment. FIG. 15 is a diagram schematically showing an image reading example of the fifth embodiment. FIG. 16 is a diagram schematically showing an image reading example of the fifth embodiment. FIG. 17 is a diagram showing a modified example of the image sensor according to the sixth embodiment. FIG. 18 is a diagram showing another modification of the image sensor according to the seventh embodiment. FIG. 19 is a block diagram showing an electrical connection of each part constituting the image reading unit according to the eighth embodiment. FIG. 20 is a block diagram showing an electrical connection of each part constituting the image reading unit according to the ninth embodiment. FIG. 21 is a block diagram showing an electrical connection of each part constituting the image reading unit according to the tenth embodiment. FIG. 22 is a block diagram showing an electrical connection of each part constituting the image reading unit according to the eleventh embodiment. FIG. 23 is a flowchart showing a flow of processing for removing invisible light data from visible light + invisible light data. FIG. 24 is a diagram showing a modified example of the block diagram showing the electrical connection of each portion constituting the image reading unit according to the eighth to eleventh embodiments. FIG. 25 is a diagram showing another modification of the block diagram showing the electrical connection of each portion constituting the image reading unit according to the eighth to eleventh embodiments. FIG. 26 is a block diagram showing an electrical connection of each part constituting the image reading unit according to the twelfth embodiment. FIG. 27 is a diagram showing an example of the offset addition process. FIG. 28 is a diagram showing another example of the offset addition process.

Hereinafter, embodiments of an image data processing device, an image reading device, an image forming device, and an image data processing method will be described in detail with reference to the accompanying drawings.

(First Embodiment)
FIG. 1 is a diagram showing a configuration of an example of an image data processing device 100 according to the first embodiment. In FIG. 1, the image data processing device 100 is an image forming device generally called a multifunction device, which has at least two functions of a copy function, a printer function, a scanner function, and a facsimile function.

The image data processing device 100 has an image reading unit 101 and an ADF (Automatic Document Feeder) 102, which are image reading devices, and an image forming unit 103 below the image reading unit 101. In order to explain the internal configuration of the image forming unit 103, the external cover is removed to show the internal configuration.

The ADF 102 is a document support unit that positions a document for reading image data at a reading position. The ADF 102 automatically conveys the document placed on the mounting table to the reading position. The image reading unit 101 reads the document conveyed by the ADF 102 at a predetermined reading position. Further, the image reading unit 101 has a contact glass on the upper surface, which is a document supporting portion on which the document is placed, and reads the document on the contact glass at the reading position. Specifically, the image reading unit 101 is a scanner having a light source, an optical system, and an image sensor such as a CCD (Charge Coupled Device) inside, and reads the reflected light of the document illuminated by the light source with the image sensor through the optical system. ..

The image forming unit 103 prints the original image data read by the image reading unit 101. The image forming unit 103 includes a manual roller 104 for manually feeding the recording paper and a recording paper supply unit 107 for supplying the recording paper. The recording paper supply unit 107 has a mechanism for feeding out the recording paper from the multi-stage recording paper paper feed cassette 107a. The supplied recording paper is sent to the secondary transfer belt 112 via the resist roller 108.

The toner image data on the intermediate transfer belt 113 is transferred to the recording paper carried on the secondary transfer belt 112 at the transfer unit 114.

Further, the image forming unit 103 includes an optical writing device 109, a tandem type image forming unit (Y, M, C, K) 105, an intermediate transfer belt 113, the secondary transfer belt 112, and the like. By the image forming process by the image forming unit 105, the image data written by the optical writing device 109 is formed as toner image data on the intermediate transfer belt 113.

Specifically, the image processing unit (Y, M, C, K) 105 has four photoconductor drums (Y, M, C, K) rotatably, and a charging roller is formed around each photoconductor drum. , A developer, a primary transfer roller, a cleaner unit, and an image forming element 106 including a static eliminator, respectively. The image forming element 106 functions in each photoconductor drum, and the image data on the photoconductor drum is transferred onto the intermediate transfer belt 113 by each primary transfer roller.

The intermediate transfer belt 113 is arranged on the nip between each photoconductor drum and each primary transfer roller by being stretched by a driving roller and a driven roller. The toner image data primaryly transferred to the intermediate transfer belt 113 is secondarily transferred to the recording paper on the secondary transfer belt 112 by the secondary transfer device by running the intermediate transfer belt 113. The recording paper is conveyed to the fixing device 110 by the running of the secondary transfer belt 112, and the toner image data is fixed on the recording paper as color image data. After that, the recording paper is discharged to the output tray outside the machine. In the case of double-sided printing, the front and back sides of the recording paper are reversed by the reversing mechanism 111, and the inverted recording paper is sent onto the secondary transfer belt 112.

The image forming unit 103 is not limited to the one that forms the image data by the electrophotographic method as described above, and may be the one that forms the image data by the inkjet method.

Next, the image reading unit 101 will be described.

FIG. 2 is a cross-sectional view schematically showing the structure of the image reading unit 101. As shown in FIG. 2, the image reading unit 101 has a sensor substrate 10 including an image sensor 9 which is an image sensor, a lens unit 8, a first carriage 6, and a second carriage 7 in the main body 11. The image sensor 9 is, for example, a CCD or a CMOS image sensor. The first carriage 6 has a light source 2 and a mirror 3 which are LEDs (Light Emitting Diodes). The second carriage 7 has mirrors 4 and 5. Further, the image reading unit 101 is provided with a contact glass 1 and a reference white plate 13 on the upper surface thereof.

In the reading operation, the image reading unit 101 irradiates light from the light source 2 upward while moving the first carriage 6 and the second carriage 7 from the standby position (home position) to the sub-scanning direction (A direction). Then, the first carriage 6 and the second carriage 7 form an image of the reflected light from the document 12 on the image sensor 9 via the lens unit 8.

Further, the image reading unit 101 reads the reflected light from the reference white plate 13 to set a reference when the power is turned on or the like. That is, the image reading unit 101 moves the first carriage 6 directly under the reference white plate 13, turns on the light source 2, and forms an image of the reflected light from the reference white plate 13 on the image sensor 9, thereby adjusting the gain. Do.

FIG. 3 is a block diagram showing an optical connection of each unit constituting the image reading unit 101 according to the first embodiment, and is a configuration example in the case of reading the subject 201.

First, the first offset component os1 which is the output signal of the first image sensor 9a when the light source 2 is turned off is detected.

The first offset component os1 is an analog signal component that is electrically generated, and is different for each pixel of the image sensor and may fluctuate depending on environmental conditions such as temperature.

Next, the light source 2 irradiates the subject 201 with light having a first wavelength λ1 and a second wavelength λ2, the light is reflected by the subject 201, and the light reflected from the subject 201 is reflected by the first image sensor 9a. The first wavelength λ1 and the second wavelength λ2 are incident.

At this time, the first wavelength image data img1 + img2 + os1 obtained by adding the offset component os1 to the reflected light image data component img1 + img2 by the first wavelength λ1 and the second wavelength λ2 is obtained from the first image sensor 9a.

Next, similarly to the detection of the first offset component os1, the second offset component os2, which is the output signal of the second image sensor 9b when the light source 2 is turned off, is detected.

This second offset component os2 is also an analog signal component that is electrically generated, and is different for each pixel of the image sensor and may fluctuate depending on environmental conditions such as temperature.

Further, the light source 2 irradiates the subject 201 with light having a second wavelength λ2, the light is reflected by the subject 201, and the second image sensor 9b has a second wavelength λ2 which is the reflected light from the subject 201. Is incident.

At this time, the second image sensor 9b obtains the second wavelength image data img2 + os2 in which the offset component os2 is added to the reflected light image data component img2 by the second wavelength λ2.

This example is applied to a case where it is difficult to acquire image data of only the first wavelength λ1 such that light of the first wavelength λ1 is generated as excitation light of the second wavelength λ2. ..

Although FIG. 3 shows an example in which only the second wavelength λ2 is emitted from the light source 2, for example, the second wavelength is still emitted with the configuration of emitting light of both the first wavelength and the second wavelength. A filter that cuts the first wavelength may be provided in front of the image sensor 9b.

In the above examples, the first offset component os1, the first wavelength image data img1 + img2 + os1, the second offset component os2, and the second wavelength image data img2 + os2 are detected and acquired in this order. The order may be different.

Further, as long as a change in environmental conditions such as temperature is allowed, the detection of each offset component may be detected and held in advance at a timing completely different from the subject reading such as at the time of product shipment.

Next, the first offset component removing unit 211a removes the first offset component os1 from the first wavelength image data img1 + img2 + os1 to obtain the first wavelength image data img1 + img2. Similarly, the second offset component removing unit 211b removes the second offset component os2 from the second wavelength image data img2 + os2 to obtain the second image data img2.

Further, in the second image data component removing processing unit, the third image data img1 is obtained by removing the second image data img2 from the first image data img1 + img2. The third image data mg1 is purely read image data information when the subject 201 is read by the first wavelength λ1. Therefore, after that, image data correction / processing suitable for shading correction or the like may be performed.

Further, when the second image data img2 is used in addition to the third image data img1, it may be configured to be output from the second image data component removing unit 212a as shown in the figure.

The shading correction processing unit 221 functions as an image data correction unit, and performs shading correction on the third image data img1 and the second image data img2, respectively. The shading correction is a correction that removes fluctuations in the reading level in the main scanning direction by maintaining the reading level of the reference white plate 13 for each main scanning pixel and normalizing the document scanning data with the reading level of the reference white plate 13. ..

FIG. 4 is a diagram showing a flow of processing according to the first embodiment.

As shown in FIG. 4A, after acquiring the first wavelength image data img1 + img2 + os1, the first offset component removing unit 211a removes the offset component os1 as shown in FIG. 4B. Similarly, the second offset component removing unit 211b removes the offset component os2 after acquiring the second image data img2 + os2 shown in FIG. 4 (a).

As a result, the first image data img1 + img2, which is the light receiving component of the first image sensor 9a, and the second image data img2, which is the light receiving component of the second image sensor 9b, can be obtained.

Next, as shown in FIG. 4C, the second image data component removing processing unit 212a removes the second image data img2 from the first image data img1 + img2, and does not include the second image data. One image data, that is, the third image data mg1 is generated.

Finally, as shown in FIG. 4D, the shading correction processing unit 221 performs shading correction on the third image data mg1.

As described above, according to the present embodiment, in order to remove an unintended image data component (= second image data component included in the first image data) after appropriately removing the offset component at any time, for example, an image sensor. Even in a situation where the offset component changes with temperature or the like due to the characteristics of the above, there is no side effect of changing the data (such as deterioration of color reproducibility in the prior art), and it is possible to remove the data with high accuracy. That is, since a stable image data component can always be obtained even when the offset fluctuates, it is invisible from the visible light + invisible light read data without causing a change in the image data level or deterioration of color reproducibility. Optical data can be removed.

(Second Embodiment)
5 and 6 are diagrams schematically showing an image reading example of the second embodiment. FIG. 7 is a block diagram showing an optical connection of each part constituting the image reading unit according to the second embodiment.

In the second embodiment, the first wavelength image data img1 + img2 + os1 and the second wavelength image data img2 + os2 are A / D converted, and the digital data IMG1 + IMG2 + OS1 of the first wavelength image data and the second wavelength image are respectively. It differs from the first embodiment in that the data is converted into digital data IMG2 + OS2. Hereinafter, in the following description of the second embodiment, the description of the same part as that of the first embodiment will be omitted, and the parts different from the first embodiment will be described.

In the various signal processing units 222, A / D conversion is mainly performed on the first wavelength image data img1 + img2 + os1 and the second wavelength image data img2 + os2. However, the present invention is not limited to this processing, and general signal processing such as signal amplification, detection and adjustment of offset components, and noise removal may be performed to assist the processing in the subsequent stage.

Next, in the first offset component removing unit 211a shown in FIG. 7, the first offset component OS1 is removed from the first wavelength image data IMG1 + IMG2 + OS1 to obtain the first image data IMG1 + IMG2. Further, in the second offset component removing unit 211b, the second offset component OS2 is removed from the second wavelength image data IMG2 + OS2 to obtain the second image data IMG2.

Since the first offset component OS1 and the second offset component OS2 are components obtained from the image sensor when the light source 2 is turned off, for example, they may be detected at any time, or they may be detected in advance at the time of shipment. You may prepare for it.

Next, the second image data component removing processing unit 212a obtains the third image data IMG1 by removing the second image data IMG2 from the first image data IMG1 + IMG2.

Since the image data of the subject 201 with the first wavelength can be obtained by these processes, the same processing as the conventional shading correction may be performed thereafter.

FIG. 8 is a diagram showing a flow of processing according to the second embodiment.

As shown in FIG. 8B, the first offset component removing unit 211a removes the offset component OS1 from the digital data (IMG1 + IMG2 + OS1) of the first wavelength image data shown in FIG. 8A.

Similarly, the second offset component removing unit 211b removes the offset component OS2 from the digital data (IMG2 + OS2) of the second wavelength image data shown in FIG. 8A.

As a result, the first image data IMG1 + IMG2, which is the light receiving component of the first image sensor 9a, and the second image data IMG2, which is the light receiving component of the second image sensor 9b, can be obtained.

Next, as shown in FIG. 8C, the second image data component removing processing unit 212a removes the second image data IMG2 from the first image data IMG1 + IMG2 and does not include the second wavelength image data. The first wavelength image data, that is, the digital data of the third image data IMG1 is generated.

Finally, as shown in FIG. 8D, the shading correction processing unit 221 performs shading correction on the third image data IMG1.

As described above, according to the present embodiment, since the removal processing of various data is performed by digital data, it is possible to apply a well-known digital arithmetic processing circuit, that is, the removal of unnecessary offset components and wavelength components is further performed. It can be implemented at higher speed with a simple and small-scale configuration.

(Third Embodiment)
The third embodiment is different from the second embodiment in that unnecessary invisible light components are removed with high accuracy.

When the image data is read by the image sensor, the image data of the subject 201 may be different from the visual data due to the difference in the spectral sensitivity characteristics between the human eye and the image sensor. In particular, when the image sensor has a sensitivity in the invisible light region, it is essential to remove the invisible light component in order to ensure the color reproducibility of any subject 201.

9 and 10 are diagrams schematically showing an image reading example of the third embodiment. For example, an unnecessary invisible light component is used in reading the subject 201 in which the first wavelength λ1 and the second wavelength λ2 in FIGS. 5 and 6 are set to visible light λ3 and invisible light λ4 as shown in FIGS. 9 and 10. Can be removed with high accuracy.

An example of removing such an unnecessary invisible light component with high accuracy will be described with reference to FIGS. 11 and 12. Here, FIG. 11 is a diagram showing an example of the image sensor spectral sensitivity characteristic, and FIG. 12 is a diagram showing an example of the spectral sensitivity characteristic (luminous efficiency characteristic) of the human eye.

An image sensor made of general silicon as a constituent material as shown in FIG. 11 has spectral sensitivity characteristics in the visible light wavelength range (λ1 = 400 to 780 nm) of three colors of Red / Green / Blue.

That is, for the visible wavelength λ3, light having emission energy at a wavelength of 400 to 780 nm is used.

Further, the second wavelength λ2 is light having emission energy in the near infrared wavelength region (λ2 = 780 to 1100 nm), which is another wavelength region having the effective sensitivity of silicon.

By doing so, it becomes possible to read the subject 201 and convert it into image data.

As shown in FIG. 12, the human eye is significantly different from the image sensor 9 in the sensitivity of the near-infrared light region (invisible light region) after 780 nm. This is because the silicon constituting the pixels of the image sensor 9 has sensitivity, which is a big difference from the human eye.

That is, when a general image sensor having sensitivity in the invisible light region is used, it is essential to remove the invisible light component in order to ensure the color reproducibility of any subject 201.

(Fourth Embodiment)
The fourth embodiment is different from the third embodiment in that visible light and infrared light are used.

Here, FIGS. 13 and 14 are diagrams schematically showing an image reading example of the fourth embodiment. Since the description of the reading operation and the signal processing in FIGS. 13 and 14 is the same as that shown in FIGS. 5 and 6, the description here will be omitted.

As shown in FIGS. 13 and 14, reading of the subject 201 using visible light and infrared light can be inexpensively and easily configured with a general silicon image sensor.

The process of removing the infrared light reading component img2 from the image data read by the first image sensor 9a according to the present embodiment is an effective means for ensuring highly accurate color reproducibility.

(Fifth Embodiment)
The fifth embodiment is different from the third embodiment in that the light source is composed of two different types of visible light components (visible light λ3 and visible light λ6).

Here, FIGS. 15 and 16 are diagrams schematically showing an image reading example of the fifth embodiment. As shown in FIGS. 15 and 16, the processes shown in FIGS. 5 and 6 can be applied even when the light source is composed of two different types of visible light components (visible light λ3 and visible light λ6).

When reading the subject 201, there is a method in which one image sensor having a sensitivity characteristic in a wide wavelength range is configured and the reflected light component of each color is read by switching the light source.

According to the present embodiment, for example, the Green component contained in the Red LED, which is one of the light sources, can be removed by using the data read by the Green LED. That is, according to the present embodiment, it is possible to obtain highly accurate color image data closer to a single color.

(Sixth Embodiment)
In each of the above-described embodiments, the image sensor 9 includes the first image sensor 9a and the second image sensor 9b, but the present invention is not limited to this. The sixth embodiment is different from the other embodiments in that the image sensor 9 is composed of a single image sensor and includes optical filters having different transmission characteristics.

Here, FIG. 17 is a diagram showing a modified example of the image sensor 9 according to the sixth embodiment. As shown in FIG. 17, the first image sensor 9a and the second image sensor 9b are configured by a single image sensor 9c, and the first image sensor 9c transmits light of the first wavelength λ1 and the second wavelength λ2. An optical filter 213a may be provided, and a second optical filter 213b that transmits the second wavelength λ and reflects or absorbs the first wavelength λ1 may be provided.

According to the present embodiment, in the other embodiments, reading is performed a plurality of times while switching the emission wavelength of the light source, whereas the first wavelength image data img1 + img2 + os1 and the second wavelength image data img2 + os2 are read once. Since both of them can be acquired, faster reading becomes possible.

(7th Embodiment)
The seventh embodiment is different from the other embodiments in that the image sensor 9 is an image sensor including R / G / B / IR pixels capable of reading in each color.

Here, FIG. 18 is a diagram showing another modification of the image sensor 9 according to the seventh embodiment. As shown in FIG. 18, the image sensor 9 may be an image sensor 9d including R / G / B / IR pixels capable of reading in each color. This makes it possible to read full-color and invisible light image data at the same time.

In FIG. 18, r, g, b, and ir are the read signal components of the subject 201 output from the image sensor, and ros, gos, bos, and iros are their respective offset signal components, R, G, B, and IR. Ros, Gos, Bos, and IRos are digital signals after A / D conversion, and the first offset component removing section 211a and the second offset component removing section 211b are the first to fourth offset component removing sections 211a. It becomes ~ 211d.

(8th Embodiment)
Next, the eighth embodiment will be described.

The eighth embodiment is different from the other embodiments in that the data correction unit 214 is provided in front of the second image data component removal processing unit 212a.

FIG. 19 is a block diagram showing an electrical connection of each part constituting the image reading unit 101 according to the eighth embodiment.

There are cases where the reading conditions are different for each reading by visible light and invisible light. For example, there are variations and differences in signal amplification factor, reading line period, and sensitivity of the image sensor, and in this case, there are differences in the size of invisible components contained in each data.

In order to correct this difference and enable more accurate removal by the second image data component removal processing unit 212a in the subsequent stage, as shown in FIG. 19, the second image data component removal processing unit 212a A data correction unit 214 is provided in the previous stage.

The data correction unit 214 corrects the size of the invisible light data component included in the visible light + invisible light data and the invisible light data component.

Here, an example of correction by the data correction unit 214 will be described.

_{For example, the data correction unit 214 uses the coefficients α 1} , β ₁ , and an arbitrary constant k ₁ that change depending on the reading conditions for the output data of the first image sensor 9a and the second image sensor 9b, respectively. , Perform the following correction calculation.
α ₁ (IMG1 + IMG2) × k ₁ / α ₁ = k ₁ (IMG1 + IMG2) ・ ・ ・ Equation (1)
β ₁・ IMG 2 × k ₁ / β ₁ = K ₁・ IMG 2 ・ ・ ・ Equation (2)

In the second image data component removing processing unit 212a in the subsequent stage, the removal of the second image data IMG2 is realized by taking the difference between the equation (1) and the equation (2).

As described above, according to the present embodiment, the second image data IMG2 can be removed with high accuracy even when the image data is processed by the data correction.

(9th embodiment)
Next, a ninth embodiment will be described.

The ninth embodiment is different from the other embodiments in that the correction of each data in the data correction unit 214a is corrected by the ratio of the signal amplification factor set in the various signal processing units 222.

FIG. 20 is a block diagram showing an electrical connection of each part constituting the image reading unit 101 according to the ninth embodiment. As shown in FIG. 20, the correction of each data in the data correction unit 214a is corrected by the ratio of the signal amplification factor set in the various signal processing units 222.

As a result, it is possible to deal with the amplification factor that changes to the optimum value at any time, and it is possible to easily improve the removal accuracy of the second image data IMG2.

For example, the data correction unit 214a performs the following correction calculation using _{the signal amplification factors α 2} , β ₂ and the arbitrary constant k ₂ of the output data of the first image sensor 9a and the second image sensor 9b, respectively.
α ₂ (IMG1 + IMG2) × k ₂ / α ₂ = k ₂ (IMG1 + IMG2) ・ ・ ・ Equation (3)
β ₂・ IMG _{2 × k 2} / β ₂ = K ₂・ IMG 2 ・ ・ ・ Equation (4)

As described above, according to the present embodiment, the second image data IMG2 can be easily and highly accurately removed.

(10th Embodiment)
Next, a tenth embodiment will be described.

The tenth embodiment is different from the other embodiments in that the correction of each data in the data correction unit 214b is corrected by the ratio of the reading line period of the first image sensor 9a and the second image sensor 9b.

FIG. 21 is a block diagram showing an electrical connection of each part constituting the image reading unit 101 according to the tenth embodiment. As shown in FIG. 21, the correction of each data in the data correction unit 214b is corrected by the ratio of the reading line period of the first image sensor 9a and the second image sensor 9b. When improving each image quality (S / N ratio), it is effective to change (longen) the reading line period.

This makes it possible to easily improve the accuracy of removing invisible components.

For example, the data correcting unit 214b includes a first image sensor 9a, the second image sensor 9b reading line period ratio alpha ₃ of _using a beta _3, and an arbitrary constant k _3, a correction operation is performed below.
α ₃ (IMG1 + IMG2) × k ₃ / α ₃ = k ₃ (IMG1 + IMG2) ・ ・ ・ Equation (5)
β ₃・ IMG 2 × k ₃ / β ₃ = K ₃・ IMG 2 ・ ・ ・ Equation (6)

As described above, according to the present embodiment, the invisible component can be removed with high accuracy.

The data correction unit 214 may perform correction using both the amplification factor and the ratio of the read line period.

(11th Embodiment)
Next, the eleventh embodiment will be described.

The eleventh embodiment is different from the other embodiments in that the reference second wavelength data is acquired in advance and the change is estimated from the ratio with the second wavelength data reacquired at the time of data correction. different.

FIG. 22 is a block diagram showing an electrical connection of each unit constituting the image reading unit 101 according to the eleventh embodiment. The level may change depending on the data acquisition timing, such as changes in characteristics that depend on the ambient temperature. Therefore, in the present embodiment, as shown in FIG. 22, the reference second wavelength data is acquired in advance. After that, by estimating the change amount from the ratio with the second wavelength data reacquired at the time of data correction at the time of reading the subject 201, more accurate removal processing becomes possible.

Next, the first wavelength λ1 is set to visible light and the second wavelength is set to invisible light, and the second image data read by the second image sensor is read from the image data of visible light + invisible light read by the first image sensor. The flow of processing when removing image data will be described.

Here, FIG. 23 is a flowchart showing a flow of processing for removing invisible light data from visible light + invisible light data. As shown in FIG. 23, first, the control unit 23 controls the light source driving unit 24 and the image sensor 9 at the timing of initial adjustment and the like to turn on only the light (invisible light) of the second wavelength of the light source 2. Acquire reference data as a reference in the state (step S1).

The acquired reference data is processed by using the signal components from which the offset components have been removed, as in the examples shown in the first embodiment to the tenth embodiment.

At this time, assuming that the output data from the first image sensor 9a and the second image sensor 9b is IV ₁ , and the coefficients representing the difference in amplification factor and sensitivity are α ₄ and β ₄ , the results are as follows.

[Light source: visible light off, invisible light on]
Output data of the first image sensor: α ₄ IV ₁
Output data of the second image sensor: β ₄ IV ₁

In particular, since the first image sensor 9a has sensitivity in both visible and invisible wavelength regions, the invisible light reference data in the first image sensor 9a is acquired here as the visible light source off and the invisible light source on. , It is retained as data for removing invisible light later.

Next, when the reading of the subject 201 is instructed (Yes in step S2), the control unit 23 controls the light source driving unit 24 and the image sensor 9 to acquire the reference data again prior to reading the subject 201. (Step S3).

Since both the visible light source and the invisible light source are lit when the subject 201 is read, the control unit 23 controls the light source driving unit 24 and the image sensor 9 and acquires the reference data at this time under the same conditions. To do. The acquired reference data is also provided as the second data for the removal process.

On the other hand, there is a possibility that the ambient environment such as temperature has changed between the time when the reference data acquired in advance is acquired and the time when the subject 201 is read. For example, the amount of light emitted from the reading light source and the sensitivity of the image sensor change. Can be done. Assuming that this fluctuation amount is n, the output data from the first image sensor 9a and the second image sensor 9b are as follows.

[Light source: visible light on, invisible light on]
Output data of the first image sensor: nα ₄ (IMGV ₁ + IV ₁ )
Output data of the second image sensor: nβ ₄ IV ₁

Following the reacquisition of the reference data in step S3, the control unit 23 controls the light source driving unit 24 and the image sensor 9 to read the subject 201 (step S4). The output data from the first image sensor 9a and the second image sensor 9b are as follows.

[Light source: visible light on, invisible light on]
Output data of the first image sensor: nα ₄ (V ₂ + IV ₂ )
Output data of the second image sensor: nβ ₄ IV ₂

_{Next, the data correction unit 214 calculates the correction coefficient k 4} using the two output data of the first image sensor 9a and the second image sensor 9b (step S5). With this correction coefficient k ₄ , the sensitivity of the first image sensor 9a and the second image sensor 9b, the difference in the amount of incident light, and the like are corrected.

Correction coefficient k ₄ = α ₄ IV ₁ / β ₄ IV ₁

Finally, the second image data component removal processing unit 212a performs the removal processing of the invisible light component IV ₂ from the read data of the subject 201 of the first image sensor 9a (step S6).

nα ₄ (V ₂ + IV ₂ ) -nβ ₄ IV ₂ × k ₄ = nα ₄ V ₂

The coefficient nα ₄ of the visible light reading data V ₂ of the subject 201 is removed in the shading correction processing (normalization processing) in the shading correction processing unit 221 in the subsequent stage.

In the present embodiment, the correction coefficient calculation (step S5) is immediately before the removal calculation (step S6), but the present invention is not limited to this, and any execution timing is between steps S2 and S6. There may be.

By setting the reference data acquisition target to the reference white plate 13 mounted on a general image reading device, it is possible to stably acquire the data and further improve the accuracy.

Further, the reference data using the reference white plate 13 acquired in step S3 can serve as both invisible light removal and shading correction data. In that case, it is necessary to remove the invisible light component in the correction coefficient calculation (step S5) and the removal calculation (step S6) of the reference white plate data, and the processing is performed by the following calculation in the same manner as the subject data.

[Calculation of correction coefficient]
Correction coefficient k ₄ = α ₄ IV ₁ / β ₄ IV ₁・ ・ ・ Similar to data processing of subject 201

[Invisible light removal processing]
nα ₄ (V ₁ + IV ₁ ) -nβ ₄ IV ₁ × k ₄ = nα ₄ V ₁ ... Removal processing using each reference data

Here, a modified example of the eighth to eleventh embodiments will be described.

FIG. 24 is a diagram showing a modified example of the block diagram showing the electrical connection of each unit constituting the image reading unit 101 according to the eighth to eleventh embodiments. The data correction unit 214 is shown as a stage before the second image data component removal processing unit 212a and after the first offset component removal unit 211a and the second offset component removal unit 211b, but is limited to this. Instead, for example, as shown in FIG. 24, it may be provided before the first offset component removing unit 211a and the second offset component removing unit 211b.

FIG. 25 is a diagram showing another modification of the block diagram showing the electrical connection of each unit constituting the image reading unit 101 according to the eighth to eleventh embodiments. As shown in FIG. 25, various signal processing units & data correction units 222a may also serve as data correction units 214. In the example shown in FIG. 25, for example, the signal amplification factor in the various signal processing units & data correction unit 222a is the same for IMG1 + IMG2 and IMG2, and the offset component to be added is also the same, so that the size of the invisible component and the offset component contained are the same. Since it is the same, each component can be removed with a simpler configuration.

As described above, according to the present embodiment, it is possible to realize the removal of invisible components that can cope with data fluctuations due to environmental changes.

(12th Embodiment)
Next, a twelfth embodiment will be described.

In the twelfth embodiment, the first offset addition processing unit 215a and the second offset addition processing unit between the various signal processing units (AD conversion processing unit) 222 and the second image data component removal processing unit Offset signal addition processing in 215b, offset signal detection processing in the first offset detection processing unit 216a and second offset detection processing unit 216b, and the first offset component removing unit 211a and using the detected offset signal. The second offset component removing unit 211b is different from other embodiments in that the offset signal is subtracted.

FIG. 26 is a block diagram showing an electrical connection of each part constituting the image reading unit 101 according to the twelfth embodiment.

The first offset addition processing unit 215a and the second offset addition processing unit 215b execute the offset addition processing.

Here, the offset addition processing in the first offset addition processing unit 215a and the second offset addition processing unit 215b will be described.

FIG. 27 is a diagram showing an example of the offset addition process. FIG. 27A is an example of noise superimposed on the image data signal from the image sensor 9. The level of the image data signal shown in FIG. 27 (a) is 0 digit (= noise component only). As shown in FIG. 27B, data less than 0 digit is clipped to 0 digit, so that a value larger than 0 digit is detected during the offset detection process (averaging process) on the image data signal receiving side, that is, It causes an error.

Therefore, the first offset addition processing unit 215a and the second offset addition processing unit 215b add an offset component to the image data signal as shown in FIG. 27 (c). In the example shown in FIG. 27 (c), an offset component of 10 bits is added. By adding the offset components to the data in this way, it is possible to prevent the occurrence of detection errors.

Here, FIG. 28 is a diagram showing another example of the offset addition processing. As shown in the sensor sensitivity spectral characteristics of FIG. 11, the invisible region (IR) has a lower sensitivity characteristic than the visible region (R / G / B), that is, the output signal level of the image sensor 9 is often smaller. Therefore, it is desirable to secure a certain level of image quality (gradation) as an image data signal by setting the amplification factor of the image data signal to be larger than that of the visible region data. On the other hand, since the amplification factor is large, the noise component is also amplified as shown in FIG. 28 (a). Further, as in the example of FIG. 27, the image data signal is clipped to 0 digit, which causes an error in the detection level. Therefore, it is effective to add an offset larger than that of the visible light read data to the invisible light read data. Therefore, in the example shown in FIG. 28 (c), the occurrence of an offset detection error is prevented by adding an offset component of 10 bits to the visible light read data and 20 bits to the invisible light read data.

It should be noted that increasing the offset component also leads to narrowing the dynamic range width that the real signal component can take, so it is desirable to set it to the optimum value for each data.

As a result, it is possible to prevent the invisible information from changing during black shading correction (subtraction), and the dynamic range of the actual information data is reduced by unnecessarily increasing the offset of the amount data. Can be prevented.

More specifically, the first offset detection processing unit 216a detects the offset component OS1 included in the output signal of the image sensor 9 and the offset component OS3 added by the first offset addition processing unit 215a. The first offset component removing unit 211a removes the offset components OS1 and OS3 detected by the first offset detection processing unit 216a.

The second offset detection processing unit 216b detects the offset component OS2 included in the output signal of the image sensor 9 and the offset component OS4 added by the second offset addition processing unit 215b. The second offset component removing unit 211b removes the offset components OS2 and OS4 detected by the second offset detection processing unit 216b.

In each of the above embodiments, the image forming apparatus of the present invention will be described with reference to an example in which the image forming apparatus of the present invention is applied to a multifunction device having at least two functions of a copy function, a printer function, a scanner function and a facsimile function. It can be applied to any image forming apparatus such as a machine, a printer, a scanner apparatus, and a facsimile apparatus.

2 Light source 9 Image sensor 9a First image sensor 9b Second image sensor 13 Reference white plate 22 Image processing device 101 Reading device 201 Subject 211a First offset component removing part 211b Second offset component removing part 211c Third offset Component removal unit 211d Fourth offset component removal unit 212a Second image data component removal processing unit 213a First optical filter 213b Second optical filter 214 Data correction unit 214a Data correction unit (amplification rate ratio)
214b Data correction unit (line period ratio)
215a First offset addition processing unit 215b Second offset addition processing unit 216a First offset detection processing unit 216b Second offset detection processing unit 221 Shading correction processing unit 222 Various signal processing units 222a Various signal processing units & data correction Department

Japanese Unexamined Patent Publication No. 2007-043427

Claims (18)

The first wavelength image data is acquired from the reflected light of both the first wavelength light and the second wavelength light emitted from the light source and incident on the first image sensor, and the first wavelength image data is obtained. The first offset component removing unit that removes the first offset component contained in the light source and generates the first image data,
The second wavelength image data is acquired from the reflected light of the light of the second wavelength that is irradiated from the light source and incident on the second image sensor, and the second offset component included in the second wavelength image data. A second offset component remover that removes the light and generates a second image data,
A third image data is generated by removing the second image data from the first image data, which is provided after the first offset component removing unit and the second offset component removing unit. The second image data component removal processing unit and
An image data processing device comprising. The first wavelength image data, the first offset component, the first image data, the second wavelength image data, the second offset component, and the second image data. The third image data is digital data.
The image data processing apparatus according to claim 1. The light of the first wavelength is visible light.
The light of the second wavelength is invisible light,
The image data processing apparatus according to claim 1 or 2. The invisible light is infrared light,
The image data processing apparatus according to claim 3, wherein the image data processing apparatus is characterized in that. The light having the first wavelength and the light having the second wavelength are both visible light.
The image data processing apparatus according to claim 1 or 2. The first image sensor includes a first optical filter having a property of transmitting light of the first wavelength and light of the second wavelength.
The second image sensor is characterized by comprising a second optical filter having a property of transmitting the light of the second wavelength and reflecting or absorbing the light of the first wavelength. The image data processing apparatus according to any one of 5. The first image sensor is composed of three color reading pixels of Red, Green, and Blue.
The second image sensor is composed of reading pixels of light having the second wavelength.
The first image sensor and the second image sensor are integrated image sensors.
The image data processing apparatus according to claim 6. A data correction unit that corrects a difference between the reading condition of the first wavelength image data and the reading condition of the second wavelength image data is provided before the second image data component removing processing unit.
The image data processing apparatus according to any one of claims 1 to 7. The data correction unit
Using the ratio of the first amplification factor given to the first wavelength image data to the second amplification factor given to the second wavelength image data, the first wavelength image data and the first wavelength image data are used. Correct one or both of the two wavelength image data,
The image data processing apparatus according to claim 8. The data correction unit
The first amplification factor given to the first wavelength image data and the second amplification factor given to the second wavelength image data are made equal to each other.
The image data processing apparatus according to claim 9. The data correction unit
Using the ratio of the first reading line period when reading the first wavelength image data to the second reading line period when reading the second wavelength image data, the first wavelength image data and the first wavelength image data are used. Correcting one or both of the second wavelength image data,
The image data processing apparatus according to claim 9. The third wavelength image data was acquired by the first image sensor for the reflected light from the reference member having only the light of the second wavelength, and the first offset component was removed by the first offset component removing unit. From the fourth wavelength image data and the fourth wavelength image data obtained by detecting the reflected light from the reference member having only the light of the second wavelength in the second image sensor, in the second offset component removing unit. The fifth wavelength image data from which the second offset component has been removed and the fifth wavelength image data have been acquired in advance.
The data correction unit calculates the ratio of the second wavelength image data and the fifth wavelength image data as a correction coefficient, and calculates the ratio.
The second image data component removing processing unit uses the fourth wavelength image data and the correction coefficient to remove the reflected light component of the light of the second wavelength from the first wavelength image data. ,
The image data processing apparatus according to any one of claims 8 to 11. The reference member is a reference white plate.
The image data processing apparatus according to claim 12. A first offset addition processing unit that adds a third offset component to the first wavelength image data or the third wavelength image data,
A second offset addition processing unit that adds a fourth offset component to the second wavelength image data or the fourth wavelength image data,
With
The first offset component removing unit includes a first offset detection processing unit that detects the first offset component and the third offset component contained in the first wavelength image data or the third wavelength image data. Prepare,
The second offset component removing unit includes a second offset detection processing unit that detects the second offset component and the fourth offset component contained in the second wavelength image data or the fourth wavelength image data. Prepare, prepare
The image data processing apparatus according to any one of claims 1 to 13. The second offset component is larger than the first offset component.
The image data processing apparatus according to any one of claims 1 to 14. A light source that irradiates the subject with light of the first wavelength and light of the second wavelength,
An image sensor that reads the reflected light from the subject due to the light emitted from the light source, and
The image data processing apparatus according to any one of claims 1 to 15.
An image reading device comprising. The image reading device according to claim 16 and
An image forming unit that forms an image on a recording medium based on the image data read by the image reading device, and an image forming unit.
An image forming apparatus comprising. This is an image processing method in an image data processing device.
The first offset component contained in the first wavelength image data obtained from the reflected light of both the first wavelength light and the second wavelength light emitted from the light source and incident on the image sensor is removed. The first offset component removal step to generate one image data,
The second image data is generated by removing the second offset component included in the second wavelength image data obtained from the reflected light of the light of the second wavelength that is irradiated from the light source and incident on the image sensor. The second offset component removal step and
After the processing of the first offset component removing step and the second offset component removing step, the second image data is removed from the first image data to generate a third image data. Component removal processing step and
An image data processing method comprising.

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