Image data processing device, image reading device, image forming device, and image data processing method

Abstract

To prevent a change in the level of image data and a deterioration in color reproducibility and generate visible light read data from visible light+invisible light read data.SOLUTION: An image data processing apparatus comprises: a first offset component removal unit that acquires first wavelength image data from reflected light of both light with a first wavelength and light with a second wavelength emitted from a light source and incident on a first image sensor, and removes a first offset component included in the first wavelength image data to generate first image data; a second offset component removal unit that acquires second wavelength image data from reflected light of the light with the second wavelength emitted from the light source and incident on a second image sensor, and removes a second offset component included in the second wavelength image data to generate second image data; and a second image data component removal processing unit that is provided on the subsequent stage of the first offset component removal unit and the second offset component removal unit, and removes the second image data from the first image data to generate third image data.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an image data processing device, an image reading device, an image forming device, and an image data processing method. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is already known a technique for simultaneously irradiating a subject with visible light and invisible light to read an image, and obtaining invisible light image data or visible light image data from the obtained read data.

[0003] For example, Patent Document 1 discloses a technique for removing infrared wavelength components from visible wavelength components including infrared wavelength components without using an optical infrared cut filter. More specifically, according to the technique disclosed in Patent Document 1, in order to obtain the visible wavelength components, infrared+visible wavelength components are detected by a visible component image sensor, and at the same time, infrared wavelength components are detected by an infrared component image sensor. Then, according to the technique disclosed in Patent Document 1, these detection results are used to remove the infrared wavelength components from the infrared+visible wavelength components before shading correction processing, thereby extracting only the visible wavelength components. Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the conventional technology, the infrared+visible wavelength component is detected by the visible component image sensor, and the infrared wavelength component is simultaneously detected by the infrared component image sensor, and the infrared wavelength component is directly removed from the infrared+visible wavelength component. In other words, there was a problem that the visible wavelength component was partially removed due to the influence of the offset component (component other than the normal read information) contained in the output information of each image sensor, resulting in a change in the data level of the visible light image (monochrome image) and a deterioration in color reproducibility (color image).

[0005] The present invention has been made in consideration of the above, and aims to suppress changes in image data levels and deterioration of color reproducibility, and generate visible light read data from visible light + invisible light read data. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention provides a first offset component removal unit that acquires first wavelength image data from reflected light of both light of a first wavelength and light of a second wavelength that are irradiated from a light source and incident on a first image sensor, and removes a first offset component contained in the first wavelength image data to generate first image data, a second offset component removal unit that acquires second wavelength image data from reflected light of light of the second wavelength that is irradiated from the light source and incident on a second image sensor, and removes a second offset component contained in the second wavelength image data to generate second image data, a second image data component removal processing unit that is provided after the first offset component removal unit and the second offset component removal unit, and removes the second image data from the first image data to generate third image data, a shading correction processing unit provided at a stage subsequent to the second image data component removal processing unit and performing shading correction processing on the third image data and the second image data; The present invention is characterized by comprising: Effect of the Invention

[0007] According to the present invention, it is possible to suppress changes in image data and deterioration in color reproducibility, and to generate visible light read data from visible light+invisible light read data. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of an image processing apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view illustrating an example of the structure of the image reading unit. [Diagram 3] FIG. 3 is a block diagram showing optical connections of the components constituting the image reading unit according to the first embodiment. As shown in FIG. [Figure 4]FIG. 4 is a diagram illustrating a process flow according to the first embodiment. [Diagram 5] FIG. 5 is a diagram illustrating an example of image reading according to the second embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of image reading according to the second embodiment. [Figure 7] FIG. 7 is a block diagram showing optical connections of the components constituting the image reading unit according to the second embodiment. [Figure 8] FIG. 8 illustrates a process flow according to the second embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of image reading according to the third embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of image reading according to the third embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of the spectral sensitivity characteristic of an image sensor. [Figure 12] FIG. 12 is a diagram showing an example of the spectral sensitivity characteristic (relative luminous efficiency characteristic) of the human eye. [Figure 13] FIG. 13 is a diagram illustrating an example of image reading according to the fourth embodiment. [Figure 14] FIG. 14 is a diagram illustrating an example of image reading according to the fourth embodiment. [Figure 15] FIG. 15 is a diagram illustrating an example of image reading according to the fifth embodiment. [Figure 16] FIG. 16 is a diagram illustrating an example of image reading according to the fifth embodiment. [Figure 17] FIG. 17 is a diagram showing a modification of the image sensor according to the sixth embodiment. [Figure 18] FIG. 18 is a diagram showing another modified example of the image sensor according to the seventh embodiment. [Figure 19] FIG. 19 is a block diagram showing electrical connections of the components constituting an image reading unit according to the eighth embodiment. [Figure 20] FIG. 20 is a block diagram showing electrical connections of the components constituting an image reading unit according to the ninth embodiment. [Figure 21] FIG. 21 is a block diagram showing electrical connections of the components constituting an image reading unit according to the tenth embodiment. [Figure 22] FIG. 22 is a block diagram showing electrical connections of the components constituting an image reading unit according to the eleventh embodiment. [Diagram 23] FIG. 23 is a flowchart showing the flow of a process for removing invisible light data from visible light+invisible light data. [Figure 24] FIG. 24 is a block diagram showing a modification of the electrical connections of the components constituting the image reading unit according to the eighth to eleventh embodiments. [Diagram 25] FIG. 25 is a block diagram showing another modification of the electrical connections of the components constituting the image reading unit according to the eighth to eleventh embodiments. [Figure 26] FIG. 26 is a block diagram showing electrical connections of the components constituting an image reading unit according to the twelfth embodiment. As shown in FIG. [Figure 27] FIG. 27 illustrates an example of the offset addition process. [Figure 28] FIG. 28 is a diagram illustrating another example of the offset addition process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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.

[0010] (First embodiment) Fig. 1 is a diagram showing an example of a configuration of an image data processing device 100 according to a first embodiment. In Fig. 1, the image data processing device 100 is an image forming device generally called a multifunction device having at least two functions of a copy function, a printer function, a scanner function, and a facsimile function.

[0011] The image data processing device 100 has an image reading unit 101, which is an image reading device, and an ADF (Automatic Document Feeder) 102, and below that has an image forming unit 103. In order to explain the internal configuration of the image forming unit 103, the external cover is removed to show the internal configuration.

[0012] The ADF 102 is an original support unit that positions an original, the image of which is to be read, at a reading position. The ADF 102 automatically transports an original placed on a placement table to the reading position. The image reading unit 101 reads the original transported by the ADF 102 at a predetermined reading position. The image reading unit 101 also has a contact glass on its upper surface, which is an original support unit on which an original is placed, and reads the original on the contact glass, which is the reading position. Specifically, the image reading unit 101 is a scanner that includes a light source, an optical system, and an image sensor such as a CCD (Charge Coupled Device), and reads the reflected light from an original illuminated by a light source through the optical system with the image sensor.

[0013] The image forming unit 103 prints the document image data read by the image reading unit 101. The image forming unit 103 has a manual feed roller 104 for manually feeding recording paper, and a recording paper supply unit 107 for supplying recording paper. The recording paper supply unit 107 has a mechanism for feeding recording paper from a multi-stage recording paper feed cassette 107a. The supplied recording paper is sent to a secondary transfer belt 112 via a registration roller 108.

[0014] The toner image data on the intermediate transfer belt 113 is transferred to the recording paper conveyed on the secondary transfer belt 112 in a transfer section 114 .

[0015] The image forming unit 103 also includes an optical writing device 109, tandem imaging units (Y, M, C, K) 105, an intermediate transfer belt 113, and the secondary transfer belt 112. Through an image creation process by the imaging units 105, the image data written by the optical writing device 109 is formed on the intermediate transfer belt 113 as toner image data.

[0016] Specifically, the imaging unit (Y, M, C, K) 105 has four rotatable photoconductor drums (Y, M, C, K), and is provided with imaging elements 106 including a charging roller, a developing unit, a primary transfer roller, a cleaner unit, and a static eliminator around each photoconductor drum. The imaging elements 106 function for each photoconductor drum, and image data on the photoconductor drum is transferred onto the intermediate transfer belt 113 by each primary transfer roller.

[0017] The intermediate transfer belt 113 is stretched across a drive roller and a driven roller in the nip between each photosensitive drum and each primary transfer roller. The toner image data primarily transferred onto the intermediate transfer belt 113 is secondarily transferred to the recording paper on the secondary transfer belt 112 by the secondary transfer device as the intermediate transfer belt 113 runs. The recording paper is transported to the fixing device 110 as the secondary transfer belt 112 runs, and the toner image data is fixed onto the recording paper as color image data. The recording paper is then discharged to a paper discharge tray outside the machine. In the case of double-sided printing, the front and back of the recording paper are inverted by the inversion mechanism 111, and the inverted recording paper is sent onto the secondary transfer belt 112.

[0018] The image forming unit 103 is not limited to one that forms image data by the electrophotographic method as described above, but may be one that forms image data by an inkjet method.

[0019] Next, the image reading unit 101 will be described.

[0020] Fig. 2 is a cross-sectional view showing an example of the structure of the image reading unit 101. As shown in Fig. 2, the image reading unit 101 has a sensor board 10 equipped with an image sensor 9, which is an imaging element, a lens unit 8, a first carriage 6, and a second carriage 7 in a main body 11. The image sensor 9 is, for example, a CCD or CMOS image sensor. The first carriage 6 has a light source 2, which is an LED (Light Emitting Diode), and a mirror 3. The second carriage 7 has mirrors 4 and 5. In addition, the image reading unit 101 has a contact glass 1 and a reference white plate 13 on the upper surface.

[0021] In the reading operation, the image reading unit 101 irradiates light upward from the light source 2 while moving the first carriage 6 and the second carriage 7 from a standby position (home position) in the sub-scanning direction (direction A). Then, the first carriage 6 and the second carriage 7 form an image on the image sensor 9 via the lens unit 8 using the light reflected from the original 12.

[0022] Furthermore, when the power is turned on, the image reading unit 101 sets a reference by reading the reflected light from the reference white plate 13. That is, the image reading unit 101 moves the first carriage 6 to directly below 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 performing gain adjustment.

[0023] FIG. 3 is a block diagram showing optical connections of the components constituting image reading unit 101 according to the first embodiment, and shows an example of the configuration when reading subject 201. As shown in FIG.

[0024] First, the first offset component os1, which is the output signal from the first image sensor 9a when the light source 2 is turned off, is detected.

[0025] This first offset component os1 is an electrically generated analog signal component, which differs for each pixel of the image sensor and can also vary depending on environmental conditions such as temperature.

[0026] Next, the light source 2 irradiates the subject 201 with light of a first wavelength λ1 and a second wavelength λ2, which are reflected by the subject 201, and the first wavelength λ1 and the second wavelength λ2, which are reflected light from the subject 201, are incident on the first image sensor 9a.

[0027] At this time, the first image sensor 9a obtains first wavelength image data img1+img2+os1 in which an offset component os1 is added to the reflected light image data components img1+img2 due to the first wavelength λ1 and the second wavelength λ2.

[0028] Next, similarly to the detection of the first offset component os1, a second offset component os2 which is the output signal of the second image sensor 9b when the light source 2 is in an off state is detected.

[0029] This second offset component os2 is also an electrically generated analog signal component, and differs for each pixel of the image sensor, and may also vary depending on environmental conditions such as temperature.

[0030] Furthermore, the light source 2 irradiates the subject 201 with light of the second wavelength λ2, which is reflected by the subject 201, and the reflected light from the subject 201, that is, the second wavelength λ2, enters the second image sensor 9b.

[0031] At this time, the second image sensor 9b obtains second wavelength image data img2+os2 in which an offset component os2 is added to the reflected light image data component img2 of the second wavelength λ2.

[0032] This example is applied to a case where it is difficult to obtain image data of only the first wavelength λ1, for example, when excitation light of the second wavelength λ2 generates light of the first wavelength λ1.

[0033] Although FIG. 3 shows an example in which only the second wavelength λ2 is emitted from the light source 2, it is also possible to provide a filter in front of the second image sensor 9b that cuts out the first wavelength while maintaining the configuration in which light of both the first wavelength and the second wavelength is emitted.

[0034] In the example shown above, 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, but the order may be different.

[0035] Furthermore, if changes in environmental conditions such as temperature are within an allowable range, the offset components may be detected and stored in advance at a timing completely different from the time of subject scanning, such as at the time of product shipment.

[0036] Next, the first offset component os1 is removed from the first wavelength image data img1+img2+os1 in the first offset component removal unit 211a to obtain the first wavelength image data img1+img2. Similarly, the second offset component os2 is removed from the second wavelength image data img2+os2 in the second offset component removal unit 211b to obtain the second image data img2.

[0037] Furthermore, in the second image data component removal processing unit, the second image data img2 is removed from the first image data img1+img2 to obtain the third image data img1. The third image data img1 is pure read image data information obtained when the subject 201 is read using the first wavelength λ1. Therefore, after that, image data correction and processing such as shading correction may be performed as necessary.

[0038] Furthermore, when the second image data img2 is used in addition to the third image data img1, it may be configured so that they are output from the second image data component removal unit 212a as shown in the figure.

[0039] 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. The shading correction is a correction that removes fluctuations in the read level in the main scanning direction by retaining the read level of the reference white board 13 for each main scanning pixel and normalizing the document read data with the read level of the reference white board 13.

[0040] FIG. 4 is a diagram illustrating a process flow according to the first embodiment.

[0041] As shown in Fig. 4(a), after acquiring the first wavelength image data img1+img2+os1, the first offset component removal unit 211a removes the offset component os1 as shown in Fig. 4(b). Similarly, after acquiring the second image data img2+os2 shown in Fig. 4(a), the second offset component removal unit 211b removes the offset component os2.

[0042] As a result, it is possible to obtain first image data img1+img2 which are the light receiving components of the first image sensor 9a, and second image data img2 which are the light receiving components of the second image sensor 9b.

[0043] Next, as shown in Figure 4(c), the second image data component removal processing unit 212a removes the second image data img2 from the first image data img1+img2 to generate first image data that does not include the second image data, i.e., the third image data img1.

[0044] Finally, as shown in FIG. 4(d), the shading correction processing unit 221 performs shading correction on the third image data img1.

[0045] In this way, according to this embodiment, since unintended image data components (= second image data components included in the first image data) are removed after appropriately removing offset components as needed, even in a situation where the offset components change due to temperature or the like due to the characteristics of the image sensor, there is no side effect of data change (such as deterioration of color reproducibility in the conventional technology) and it is possible to remove them with high accuracy. In other words, since stable image data components can always be obtained even when the offset fluctuates, invisible light data can be removed from visible light + invisible light read data without causing changes in the image data level or deterioration of color reproducibility.

[0046] (Second embodiment) Fig. 5 and Fig. 6 are diagrams that show an example of image reading according to the second embodiment. Fig. 7 is a block diagram showing optical connections of the components that constitute the image reading unit according to the second embodiment.

[0047] The second embodiment differs from the first embodiment in that the first wavelength image data img1+img2+os1 and the second wavelength image data img2+os2 are A / D converted to digital data IMG1+IMG2+OS1 of the first wavelength image data and digital data IMG2+OS2 of the second wavelength image data, respectively. In the following description of the second embodiment, descriptions of the same parts as in the first embodiment will be omitted, and only differences from the first embodiment will be described.

[0048] 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, this is not the only processing, and general signal processing such as signal amplification, detection and adjustment of offset components, and noise removal that supports subsequent processing may also be performed.

[0049] 7, the first offset component OS1 is removed from the first wavelength image data IMG1+IMG2+OS1 to obtain first image data IMG1+IMG2. Also, the second offset component removal unit 211b removes the second offset component OS2 from the second wavelength image data IMG2+OS2 to obtain second image data IMG2.

[0050] The first offset component OS1 and the second offset component OS2 may be detected at any time since they are components obtained from the image sensor when the light source 2 is turned off, or may be detected in advance, such as at the time of shipment, and stored.

[0051] Next, in the second image data component removal processing unit 212a, the second image data IMG2 is removed from the first image data IMG1+IMG2 to obtain the third image data IMG1.

[0052] By carrying out these processes, image data of the subject 201 at the first wavelength can be obtained, and thereafter, processes such as shading correction similar to those in the conventional method may be carried out.

[0053] FIG. 8 illustrates a process flow according to the second embodiment.

[0054] As shown in FIG. 8(b), a first offset component remover 211a removes the offset component OS1 from the digital data (IMG1+IMG2+OS1) of the first wavelength image data shown in FIG. 8(a).

[0055] Similarly, the second offset component remover 211b removes the offset component OS2 from the digital data (IMG2+OS2) of the second wavelength image data shown in FIG. 8(a).

[0056] As a result, first image data IMG1+IMG2, which are the light receiving components of the first image sensor 9a, and second image data IMG2, which are the light receiving components of the second image sensor 9b, can be obtained.

[0057] Next, as shown in FIG. 8(c), the second image data component removal processing unit 212a removes the second image data IMG2 from the first image data IMG1+IMG2, and generates digital data of the first wavelength image data that does not include the second wavelength image data, i.e., the third image data IMG1.

[0058] Finally, as shown in FIG. 8(d), the shading correction processing unit 221 performs shading correction on the third image data IMG1.

[0059] As described above, according to this embodiment, the process of removing various types of data is performed on digital data, so that it is possible to apply well-known digital arithmetic processing circuits. In other words, it is possible to remove unnecessary offset components and wavelength components at higher speed with a simpler and smaller-scale configuration.

[0060] (Third embodiment) The third embodiment differs from the second embodiment in that unnecessary invisible light components are removed with high accuracy.

[0061] When image data is read by an image sensor, due to differences in the spectral sensitivity characteristics of the human eye and the image sensor, image data of the subject 201 that differs from what is seen with the naked eye may be reproduced. In particular, when the image sensor has sensitivity in the invisible light region, it is essential to remove the invisible light component in order to ensure color reproducibility for all subjects 201.

[0062] Figures 9 and 10 are schematic diagrams showing an example of image reading according to the third embodiment. For example, when reading an object 201 by changing the first wavelength λ1 and the second wavelength λ2 in Figures 5 and 6 to visible light λ3 and invisible light λ4 as shown in Figures 9 and 10, it is possible to remove unnecessary invisible light components with high accuracy.

[0063] An example of removing such unnecessary invisible light components with high accuracy will be described with reference to Fig. 11 and Fig. 12. Here, Fig. 11 is a diagram showing an example of the spectral sensitivity characteristic of an image sensor, and Fig. 12 is a diagram showing an example of the spectral sensitivity characteristic (relative luminous efficiency characteristic) of the human eye.

[0064] As shown in FIG. 11, an image sensor made of general silicon has spectral sensitivity characteristics in the visible light wavelength range (λ1=400 to 780 nm) of three colors: Red, Green, and Blue.

[0065] That is, for the visible wavelength λ3, light having emission energy at wavelengths of 400 to 780 nm is used.

[0066] 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 in which silicon has effective sensitivity.

[0067] In this way, it becomes possible to read the subject 201 and convert it into image data.

[0068] 12, the human eye has a significantly different sensitivity to the near-infrared light region (invisible light region) from 780 nm onwards compared to the image sensor 9. This is because the silicon that constitutes the pixels of the image sensor 9 has sensitivity, which is a major difference from the human eye.

[0069] That is, when using a general image sensor having sensitivity in the invisible light region, in order to ensure color reproducibility for all subjects 201, it is essential to remove invisible light components.

[0070] (Fourth embodiment) The fourth embodiment differs from the third embodiment in that visible light and infrared light are used.

[0071] Here, Fig. 13 and Fig. 14 are diagrams that show an example of image reading according to the fourth embodiment. Note that the reading operation and signal processing in Fig. 13 and Fig. 14 are similar to those shown in Fig. 5 and Fig. 6, and therefore will not be described here.

[0072] As shown in FIGS. 13 and 14, reading of a subject 201 using visible light and infrared light can be achieved inexpensively and easily using a general silicon image sensor.

[0073] The process of removing the infrared light read component img2 from the read image data by the first image sensor 9a according to this embodiment is an effective means for ensuring highly accurate color reproducibility.

[0074] (Fifth embodiment) The fifth embodiment differs from the third embodiment in that the light source is made up of two different types of visible light components (visible light λ3 and visible light λ6).

[0075] Here, Fig. 15 and Fig. 16 are diagrams that show an example of image reading in the fifth embodiment. As shown in Fig. 15 and Fig. 16, even when the light source is composed of two different types of visible light components (visible light λ3 and visible light λ6), the processes shown in Fig. 5 and Fig. 6 can be applied.

[0076] In reading the subject 201, there is a method in which a single image sensor having sensitivity characteristics over a wide wavelength range is configured, and the reflected light components of each color are read by switching the light source.

[0077] According to this embodiment, for example, the green component contained in a red LED, which is one of the light sources, can be removed by using the data read by the green LED. In other words, according to this embodiment, it is possible to obtain highly accurate color image data that is closer to a single color.

[0078] (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 is not limited to this. The sixth embodiment differs from the other embodiments in that the image sensor 9 is configured as a single image sensor and includes optical filters having different transmission characteristics.

[0079] 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 may be configured as a single image sensor 9c, which includes a first optical filter 213a that transmits light of the first wavelength λ1 and the second wavelength λ2, and a second optical filter 213b that transmits the second wavelength λ and reflects or absorbs the first wavelength λ1.

[0080] According to this embodiment, while in other embodiments multiple readings were performed while switching the emission wavelength of the light source, both the first wavelength image data img1+img2+os1 and the second wavelength image data img2+os2 can be obtained in a single reading, enabling faster reading.

[0081] (Seventh embodiment) The seventh embodiment differs from the other embodiments in that the image sensor 9 is an image sensor having R / G / B / IR pixels capable of reading in each color.

[0082] Here, Fig. 18 is a diagram showing another modified example 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 having R / G / B / IR pixels capable of reading in each color. This makes it possible to simultaneously read full-color and invisible light image data.

[0083] In FIG. 18, r, g, b, and ir are the read signal components of the subject 201 output from the image sensor, ros, gos, bos, and iros are their respective offset signal components, and R, G, B, IR, Ros, Gos, Bos, and IRos are the respective digital signals after A / D conversion, and the first offset component removal unit 211a and the second offset component removal unit 211b become the first to fourth offset component removal units 211a to 211d.

[0084] (Eighth embodiment) Next, an eighth embodiment will be described.

[0085] The eighth embodiment differs from the other embodiments in that a data correction unit 214 is provided upstream of a second image data component removal processor 212a.

[0086] FIG. 19 is a block diagram showing electrical connections of the components constituting an image reading unit 101 according to the eighth embodiment.

[0087] There are cases where the reading conditions differ between visible light and invisible light reading, such as variations or differences in the signal amplification rate, reading line cycle, and image sensor sensitivity, which causes differences in the magnitude of the invisible components contained in each data.

[0088] In order to correct this difference and enable more accurate removal in the subsequent second image data component removal processing unit 212a, a data correction unit 214 is provided upstream of the second image data component removal processing unit 212a, as shown in FIG. 19.

[0089] The data correction unit 214 corrects the invisible light data components contained in the visible light+invisible light data and the magnitude of the invisible light data components.

[0090] Here, an example of the correction performed by the data corrector 214 will be described.

[0091] For example, the data correction unit 214 performs the following correction calculations on the output data of the first image sensor 9a and the second image sensor 9b, using coefficients α1 and β1 that change depending on the reading conditions, and an arbitrary constant k1. α1(IMG1+IMG2)×k1 / α1=k1(IMG1+IMG2)...Equation (1) β1·IMG2×k1 / β1=K1·IMG2···Formula (2)

[0092] In the subsequent second image data component removal processing unit 212a, the removal of the second image data IMG2 is realized by taking the difference between equation (1) and equation (2).

[0093] As described above, according to this embodiment, the second image data IMG2 can be removed with high accuracy by data correction even in a state where the image data has been processed.

[0094] Ninth embodiment Next, a ninth embodiment will be described.

[0095] The ninth embodiment differs from the other embodiments in that the data correction unit 214a corrects each piece of data according to the ratio of the signal amplification factor set in the various signal processing unit 222.

[0096] Fig. 20 is a block diagram showing electrical connections of the components 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 performed according to the ratio of the signal amplification factor set in the various signal processing unit 222.

[0097] This makes it possible to deal with an amplification factor that changes to an optimal value at any time, and easily improves the accuracy of removing the second image data IMG2.

[0098] For example, the data correction unit 214a performs the following correction calculation using the signal amplification factors α2 and β2 of the output data of the first image sensor 9a and the second image sensor 9b, respectively, and an arbitrary constant k2. α2(IMG1+IMG2)×k2 / α2=k2(IMG1+IMG2)...Equation (3) β2 IMG2×k2 / β2=K2 IMG2 Formula (4)

[0099] As described above, according to this embodiment, the second image data IMG2 can be removed easily and with high accuracy.

[0100] (Tenth embodiment) Next, a tenth embodiment will be described.

[0101] The tenth embodiment differs from the other embodiments in that the data correction unit 214b corrects each piece of data based on the ratio between the reading line periods of the first image sensor 9a and the second image sensor 9b.

[0102] Fig. 21 is a block diagram showing electrical connections of the components 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 performed based on the ratio of the reading line cycles of the first image sensor 9a and the second image sensor 9b. To improve the image quality (S / N ratio) of each, it is effective to change (lengthen) the reading line cycle.

[0103] This makes it possible to easily improve the accuracy of removing invisible components.

[0104] For example, the data correction unit 214b performs the following correction calculation using a ratio α3, β3 of the reading line periods of the first image sensor 9a and the second image sensor 9b, and an arbitrary constant k3. α3(IMG1+IMG2)×k3 / α3=k3(IMG1+IMG2)...Equation (5) β3·IMG2×k3 / β3=K3·IMG2···Formula (6)

[0105] In this way, according to this embodiment, invisible components can be removed with high accuracy.

[0106] The data correction section 214 may perform the correction using both the amplification factor and the ratio of the reading line period.

[0107] (Eleventh embodiment) Next, an eleventh embodiment will be described.

[0108] The eleventh embodiment differs from the other embodiments in that reference second wavelength data is acquired in advance, and the amount of change is estimated from the ratio to the second wavelength data reacquired during data correction.

[0109] Fig. 22 is a block diagram showing electrical connections of the components constituting the image reading unit 101 according to the eleventh embodiment. The level may change depending on the timing of data acquisition, such as due to changes in characteristics dependent on the ambient temperature. Therefore, in this embodiment, reference second wavelength data is acquired in advance, as shown in Fig. 22. Thereafter, the change is estimated from the ratio with the second wavelength data reacquired during data correction when reading the subject 201, thereby enabling more accurate removal processing.

[0110] Next, we will explain the processing flow when the first wavelength λ1 is visible light and the second wavelength is invisible light, and the second image data read by the second image sensor is removed from the image data of visible light + invisible light read by the first image sensor.

[0111] Here, Fig. 23 is a flowchart showing the flow of a process for removing invisible light data from visible light+invisible light data. As shown in Fig. 23, first, at the timing of an initial adjustment or the like, control unit 23 controls light source driving unit 24 and image sensor 9 to obtain reference data serving as a reference in a state in which only the light of the second wavelength (invisible light) of light source 2 is turned on (step S1).

[0112] The acquired reference data is processed using signal components from which the offset components have been removed, similarly to the examples shown in the first to tenth embodiments.

[0113] In this case, if the output data from the first image sensor 9a and the second image sensor 9b are IV1, and the coefficients representing the amplification factor, the difference in sensitivity, etc. are α4 and β4, then the following is obtained.

[0114] [Light source: visible light off, invisible light on] First image sensor output data: α4IV1 Output data of the second image sensor: β4IV1

[0115] In particular, since the first image sensor 9a has sensitivity to both visible and invisible wavelength ranges, the visible light source is turned off and the invisible light source is turned on, and invisible light reference data for the first image sensor 9a is acquired and stored as data for later use in removing invisible light.

[0116] Next, when an instruction to read the subject 201 is given (Yes in step S2), the control unit 23 controls the light source driving unit 24 and the image sensor 9 to first obtain the reference data again prior to reading the subject 201 (step S3).

[0117] When reading the subject 201, both the visible light source and the invisible light source are turned on, so the control unit 23 controls the light source driving unit 24 and the image sensor 9 to obtain reference data at this time under the same conditions. The obtained reference data is also provided as the second data for the removal process.

[0118] On the other hand, the surrounding environment such as temperature may have changed between the time when the previously acquired reference data was acquired and the time when the subject 201 was read, and for example, the light emission amount of the reading light source and the sensitivity of the image sensor may change. If this change is n, the output data from the first image sensor 9a and the second image sensor 9b will be as follows.

[0119] [Light source: visible light on, invisible light on] First image sensor output data: nα4(IMGV1+IV1) Output data of the second image sensor: nβ4IV1

[0120] Following reacquisition of the reference data in step S3, control unit 23 controls light source driving unit 24 and image sensor 9 to read subject 201 (step S4). The output data from first image sensor 9a and second image sensor 9b is as follows.

[0121] [Light source: visible light on, invisible light on] First image sensor output data: nα4(V2+IV2) Output data of the second image sensor: nβ4IV2

[0122] Next, the data correction unit 214 calculates a correction coefficient k4 using the two output data of the first image sensor 9a and the second image sensor 9b (step S5). The correction coefficient k4 is used to correct the difference in sensitivity and the amount of incident light between the first image sensor 9a and the second image sensor 9b.

[0123] Correction coefficient k4=α4IV1 / β4IV1

[0124] Finally, the second image data component removal processor 212a removes the invisible light component IV2 from the read data of the subject 201 by the first image sensor 9a (step S6).

[0125] nα4(V2+IV2)-nβ4IV2×k4=nα4V2

[0126] The coefficient nα4 of the visible light read data V2 of the subject 201 is removed in the shading correction process (normalization process) in the shading correction processor 221 at the subsequent stage.

[0127] In this embodiment, the correction coefficient calculation (step S5) is performed immediately before the removal calculation (step S6), but this is not limited to this and may be performed at any timing between steps S2 to S6.

[0128] By using the reference white board 13 mounted on a general image reading device as the object for obtaining the reference data, it becomes possible to obtain data stably, and the accuracy can be further improved.

[0129] Moreover, the reference data obtained using the reference white board 13 in step S3 can serve as both invisible light removal and shading correction data. In that case, it is necessary to remove invisible light components from this reference white board data in the correction coefficient calculation (step S5) and removal calculation (step S6), and processing is performed by the following calculation, similar to the subject data.

[0130] [Calculation of correction coefficient] Correction coefficient k4 = α4IV1 / β4IV1...same as data processing for subject 201

[0131] [Invisible light removal processing] nα4(V1+IV1)-nβ4IV1×k4=nα4V1... Removal process using each standard data

[0132] Here, modifications of the eighth to eleventh embodiments will be described.

[0133] 24 is a diagram showing a modified example of the block diagram showing the electrical connections of the components constituting the image reading unit 101 according to the eighth to eleventh embodiments. The data correction unit 214 is shown as being located 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 not limited thereto, and may be located before the first offset component removal unit 211a and the second offset component removal unit 211b, for example, as shown in FIG.

[0134] Fig. 25 is a diagram showing another modified example of the block diagram showing the electrical connections of the components constituting the image reading unit 101 according to the eighth to eleventh embodiments. As shown in Fig. 25, the various signal processing unit & data correction unit 222a may also function as the data correction unit 214. In the example shown in Fig. 25, for example, by setting the signal amplification factor in the various signal processing unit & data correction unit 222a to be the same for IMG1+IMG2 and IMG2 and setting the offset component to be added to be the same, the magnitude of the invisible component contained and the offset component become the same, so that each component can be removed with a simpler configuration.

[0135] As described above, according to this embodiment, it is possible to realize invisible component removal that can also accommodate data fluctuations due to environmental changes.

[0136] (Twelfth embodiment) Next, a twelfth embodiment will be described.

[0137] The twelfth embodiment differs from the other embodiments in that, between the various signal processing units (AD conversion processing unit) 222 and the second image data component removal processing unit, a first offset addition processing unit 215a and a second offset addition processing unit 215b add offset signals, a first offset detection processing unit 216a and a second offset detection processing unit 216b detect offset signals, and a first offset component removal unit 211a and a second offset component removal unit 211b subtract offset signals using the detected offset signals.

[0138] FIG. 26 is a block diagram showing electrical connections of the components constituting the image reading unit 101 according to the twelfth embodiment.

[0139] The first offset addition processor 215a and the second offset addition processor 215b execute the offset addition process.

[0140] Here, the offset addition processing in the first offset addition processing unit 215a and the second offset addition processing unit 215b will be described.

[0141] Fig. 27 is a diagram showing an example of offset addition processing. Fig. 27(a) is an example of noise superimposed on an image data signal from an image sensor 9. The level of the image data signal shown in Fig. 27(a) is 0 digits (=only noise components). Data less than 0 digits is clipped to 0 digits as shown in Fig. 27(b), so that a value greater than 0 digits is detected during offset detection processing (averaging processing) on ​​the image data signal receiving side, i.e., an error occurs.

[0142] 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 digits is added. By adding the offset component to the data in this way, it is possible to prevent the occurrence of detection errors.

[0143] Here, FIG. 28 is a diagram showing another example of the offset addition process. As shown in the sensor sensitivity spectral characteristics of FIG. 11, the invisible region (IR) has lower sensitivity characteristics compared to the visible region (R / G / B), that is, in many cases the output signal level of the image sensor 9 is small. Therefore, it is desirable to secure a certain degree of image quality (gradation) as the 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, noise components are also amplified as shown in FIG. 28(a). Also, as in the example of FIG. 27, clipping to 0 digit of the image data signal also occurs, causing 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), an offset component of 10 digits is added to the visible light read data and 20 digits is added to the invisible light read data to prevent the occurrence of an offset detection error.

[0144] In addition, since increasing the offset component narrows the dynamic range that the actual signal component can have, it is desirable to set the offset component to an optimal value for each data.

[0145] This makes it possible to prevent invisible information from changing during black shading correction (subtraction), and also to prevent the dynamic range of the actual information data from being reduced by unnecessarily increasing the offset of the quantity data.

[0146] More specifically, the first offset detection processing unit 216a detects an offset component OS1 included in the output signal of the image sensor 9 and an offset component OS3 added by the first offset addition processing unit 215a. The first offset component removal unit 211a removes the offset components OS1 and OS3 detected by the first offset detection processing unit 216a.

[0147] 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 removal unit 211b removes the offset components OS2 and OS4 detected by the second offset detection processing unit 216b.

[0148] In each of the above embodiments, the image forming apparatus of the present invention is described as being applied to a multifunction device having at least two of the functions of a copy function, a printer function, a scanner function, and a facsimile function. However, the image forming apparatus can be applied to any image forming apparatus, such as a copier, printer, scanner device, or facsimile device. [Explanation of symbols]

[0149] 2 light source 9 Image Sensor 9a First image sensor 9b Second Image Sensor 13 Standard white board 22 Image processing device 101 Reading device 201 Subject 211a First offset component removal unit 211b Second offset component removal unit 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 section (amplification ratio) 214b Data correction section (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 units [Prior art documents] [Patent documents]

[0150] [Patent Document 1] JP 2007-043427 A

Claims

1. a first offset component removal unit that acquires first wavelength image data from both reflected light of a first wavelength and light of a second wavelength that are irradiated from a light source and incident on a first image sensor, and removes a first offset component included in the first wavelength image data to generate first image data; a second offset component removal unit that acquires second wavelength image data from reflected light of the second wavelength light irradiated from the light source and incident on a second image sensor, and removes a second offset component included in the second wavelength image data to generate second image data; and a second image data component removal processing unit that is provided after the first offset component removal unit and the second offset component removal unit and removes the second image data from the first image data to generate third image data; a shading correction processing unit provided downstream of the second image data component removal processing unit and performing shading correction processing on the third image data and the second image data; 13. An image data processing device comprising:

2. the first wavelength image data, the first offset component, the first image data, the second wavelength image data, the second offset component, the second image data, and the third image data are all digital data; 2. The image data processing apparatus according to claim 1,

3. the light of the first wavelength is visible light, The light of the second wavelength is invisible light.

3. The image data processing device according to claim 1, wherein the image data processing device is a computer.

4. The invisible light is infrared light.

4. The image data processing device according to claim 3.

5. The light of the first wavelength and the light of the second wavelength are both visible light.

3. The image data processing device according to claim 1, wherein the image data processing device is a computer.

6. the first image sensor includes a first optical filter having a characteristic of transmitting light of the first wavelength and light of the second wavelength; The second image sensor includes a second optical filter having a characteristic of transmitting light of the second wavelength and reflecting or absorbing light of the first wavelength.

6. An image data processing device according to claim 1, wherein the image data processing device is a computer.

7. the first image sensor is composed of reading pixels of three colors, red, green, and blue; the second image sensor is composed of pixels for reading light of the second wavelength, the first image sensor and the second image sensor are an integral image sensor.

7. The image data processing apparatus according to claim 6,

8. a data correction unit, which is provided in a stage preceding the second image data component removal processing unit and which corrects a difference between a reading condition of the first wavelength image data and a reading condition of the second wavelength image data; 8. An image data processing device according to claim 1, wherein the image data processing device is a computer.

9. The data correction unit is correcting one or both of the first wavelength image data and the second wavelength image data using a ratio between a first amplification factor applied to the first wavelength image data and a second amplification factor applied to the second wavelength image data; 9. The image data processing apparatus according to claim 8,

10. The data correction unit is making the first amplification factor applied to the first wavelength image data equal to the second amplification factor applied to the second wavelength image data; 10. The image data processing apparatus according to claim 9,

11. The data correction unit is correcting one or both of the first wavelength image data and the second wavelength image data using a ratio between a first read line period when reading the first wavelength image data and a second read line period when reading the second wavelength image data; 10. The image data processing apparatus according to claim 9,

12. fourth image data obtained by removing a first offset component in the first offset component removing unit from third wavelength image data obtained by detecting, in the first image sensor, reflected light from a reference member of only the light of the second wavelength; and fifth image data obtained by removing a second offset component in the second offset component removing unit from fourth wavelength image data obtained by detecting, in the second image sensor, reflected light from a reference member of only the light of the second wavelength; the data correction unit calculates a ratio between the fourth image data and the fifth image data as a correction coefficient; the second image data component removal processing unit removes a reflected light component of the light of the second wavelength from the first image data by using the second image data and the correction coefficient; 12. An image data processing device according to claim 8, wherein the image data processing device comprises:

13. The reference member is a reference white board.

13. An image data processing apparatus according to claim 12.

14. a first offset addition processing unit that adds a third offset component to the first wavelength image data to the third wavelength image data; a second offset addition processor that adds a fourth offset component to the second wavelength image data through the fourth wavelength image data; Equipped with the first offset component removal unit includes a first offset detection processing unit that detects the first offset component and the third offset component included in the first wavelength image data to the third wavelength image data, the second offset component removal unit includes a second offset detection processing unit that detects the second offset component and the fourth offset component included in the second wavelength image data to the fourth wavelength image data; 14. An image data processing apparatus according to claim 1, wherein the image data processing apparatus comprises:

15. the second offset component is greater than the first offset component; 15. An image data processing apparatus according to claim 1, wherein the image data processing apparatus comprises:

16. a light source that irradiates a subject with light of a first wavelength and light of a second wavelength; an image sensor that reads light reflected from a subject by the light irradiated from the light source; An image data processing device according to any one of claims 1 to 15; An image reading device comprising:

17. The image reading device according to claim 16, an image forming unit that forms an image on a recording medium based on image data read by the image reading device; An image forming apparatus comprising:

18. An image processing method in an image data processing device, comprising: a first offset component removing step of removing a first offset component included in first wavelength image data obtained from both reflected light of the first wavelength and light of the second wavelength irradiated from a light source and incident on an image sensor, thereby generating first image data; a second offset component removal step of removing a second offset component included in second wavelength image data obtained from reflected light of the second wavelength light irradiated from the light source and incident on the image sensor to generate second image data; a second image component removal processing step of removing the second image data from the first image data to generate third image data after the first offset component removal step and the second offset component removal step; a shading correction processing step of performing a shading correction process on the third image data and the second image data after the second image component removal processing step; 13. An image data processing method comprising:

Images