JP2006086577A - Image scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image scanner capable of sufficiently reducing smear. <P>SOLUTION: Shift pulses of a gate signal TG shift electric charges produced by a light emitting element to a transmission register (t0<t<t1). Thereafter drive pulse signals Φ1, Φ2, Φ1L are applied to the transfer register to allow the transfer register to transfer the electric charges toward an output section (t1<t<t8). In this case, the output section outputs an output signal with a signal level in response to an amount of the electric charges transferred from the transfer register. A correction value introduction section introduces a correction value of the output signal on the basis of the output signal level for a period A succeeding to a pixel part from among the output signals outputted from the output section when a halogen lamp emits light to a photo film. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus that optically reads an image and outputs a digital image signal.

  In the image reading apparatus, the original is irradiated with light by a light source such as a halogen lamp or a fluorescent lamp, and the solid-state image sensor receives reflected light or transmitted light from the original. And after converting the image signal read by the solid-state image sensor into a digital signal, it outputs to the correction | amendment part which performs a shading process etc.

  Here, a configuration of a CCD line sensor will be described as an example of a solid-state imaging device. The CCD line sensor has a large number of photoelectric conversion light receiving elements (photocells) arranged in a line and a transfer register provided along the large number of light receiving elements. Each light receiving element generates an amount of charge corresponding to the amount of light received. And the electric charge produced | generated by each light receiving element is accumulate | stored there. When a shift pulse is supplied to the CCD line sensor after a predetermined time (charge accumulation time) has elapsed, all the charges accumulated in the light receiving element are shifted to corresponding positions in the transfer register. The charge shifted to the transfer register is sequentially transferred to the transfer register by a drive pulse signal applied to the transfer register, and is output as a serial signal from the output terminal.

  In such a CCD line sensor, a part of the charge generated by the light receiving element or incident light may leak into the transfer unit, and a smear charge that is a noise charge may be generated. In the process in which the charge is transferred to the output end in the transfer register, the smear charge is added to the signal charge being transferred, and in the output image, a high-luminance portion is stripped at a position along the transfer path of the transfer register. A phenomenon called smear occurs.

Therefore, Patent Document 1 discloses a light source based on a sensor output value when a light source is turned on corresponding to an optical black pixel covered with a light-shielding film made of metal such as aluminum and disposed integrally in a CCD line sensor. A technique is disclosed in which a smear amount is derived as a correction value by subtracting the sensor output value when the light is turned off, and a correction process is performed on the output signal output from the transfer register based on the derived smear amount. .
JP 2000-350032 A

  In the optical black pixel, since the light is shielded by the light shielding film integrally disposed in the CCD line sensor, electric charges are accumulated in the capacitive element composed of the light receiving element and the light shielding film of the optical black pixel. . Since the amount of accumulated charge varies depending on the temperature, the sensor output value is affected by the temperature variation. In addition, infrared light may enter the optical black pixel through the light-shielding film, and in this case, an accurate smear amount cannot be obtained. Therefore, by using the smear amount derived based on the sensor output value corresponding to the optical black pixel, accurate correction cannot be performed, and the smear may not be sufficiently reduced.

  Accordingly, an object of the present invention is to provide an image reading apparatus capable of sufficiently reducing smear.

Means and effects for solving the problems

  An image reading apparatus according to the present invention includes a light source that irradiates light to a read original, and a plurality of light sources arranged in one direction that receive reflected light or transmitted light from the read original and generate an amount of charge corresponding to the amount of light received. And a transfer register that transfers charges generated in the light receiving element in parallel with the one direction, and an output unit that outputs an output signal having a signal level corresponding to the amount of charge transferred from the transfer register. A solid-state imaging device; and a gate signal generation unit configured to generate a gate signal including a shift pulse for simultaneously shifting charges generated in the plurality of light receiving devices from the light receiving devices to the transfer register. Furthermore, in the present invention, the charge shifted from the light receiving element to the transfer register by the shift pulse is transferred to the output unit in the transfer register, and from the light receiving element to the transfer register by the shift pulse. Until the charge is shifted from the light receiving element to the transfer register by the next shift pulse until the charge is shifted to the transfer register by the next shift pulse. Drive pulse signal generating means for generating a plurality of drive pulse signals having different phases applied to the transfer register so as to be transferred toward the output unit, and the light source irradiates the read original with light. Sometimes the light receiving element is output by a shift pulse in the output signal output from the output unit. Correction value deriving means for deriving a correction value of an output signal based on a signal level of a non-pixel portion preceding or following the pixel portion corresponding to the charge shifted from the transfer register to the transfer register, and the light source includes the read original Correction means for subtracting the correction value derived by the correction value deriving means from the signal level of the effective portion related to the effective pixel in the pixel portion in the output signal output from the output section when the light is irradiated And.

  According to this configuration, the correction value derived based on the signal level of the non-pixel portion is independent of noise peculiar to the optical black pixel due to temperature fluctuation or infrared light incidence. Therefore, it is possible to sufficiently reduce smear by correcting the output signal using the correction value. The correction value derived based on the signal level of the non-pixel part incorporates noise components other than smear such as dark current and circuit system drift in the transfer register. Therefore, by correcting the output signal using such a correction value, it is possible to sufficiently reduce noise components other than smear.

  The image reading apparatus of the present invention is stored in the adjustment value storage means for storing an adjustment value for adjusting the signal level of the output signal, and in the adjustment value storage means so that the signal level of the non-pixel portion becomes a specified value. It is preferable to further include adjustment value changing means for rewriting the adjustment value. According to this configuration, the influence of dark current in the light receiving element can be eliminated.

  In the image reading apparatus of the present invention, the correction value deriving unit may include a reference value subtracting unit that subtracts a reference value from the signal level of the non-pixel portion. According to this configuration, it is possible to correct offset level fluctuations due to temperature changes and changes with time.

  In the image reading apparatus according to the aspect of the invention, it is preferable that the correction value deriving unit includes a first average value deriving unit that derives an average value of signal levels in one non-pixel portion. According to this configuration, the accuracy of the correction value is improved.

  In the image reading apparatus of the present invention, the correction value deriving unit includes a second average value deriving unit that derives an average value of signal levels of the plurality of non-pixel portions related to a plurality of consecutive shift pulses. It is preferable. According to this configuration, the accuracy of the correction value is further improved.

  In the image reading apparatus of the present invention, the solid-state imaging device includes a plurality of transfer registers, the correction value deriving unit derives a correction value for each of the plurality of transfer registers, and the correction unit includes: A corresponding correction value may be subtracted from the signal level of the effective portion. According to this configuration, the same output signal can be obtained from a plurality of transfer registers.

  The image reading apparatus of the present invention preferably further includes monitoring means for monitoring whether or not the signal level of the non-pixel portion is within a predetermined range. According to this configuration, the black level can be monitored without the light receiving element not receiving light by turning off the light source or arranging the light shielding member.

  In another aspect, the image reading apparatus of the present invention includes a light source that irradiates light on a read original and a one-way direction that receives reflected light or transmitted light from the read original and generates an amount of electric charge corresponding to the amount of received light. A plurality of light receiving elements arranged in a line, a transfer register for transferring charges generated in the light receiving elements in parallel with the one direction, and an output signal having a signal level corresponding to the amount of charge transferred from the transfer register And a solid-state image sensor having an output unit that is formed separately from the solid-state image sensor, and at least one of the plurality of light-receiving elements serving as an effective pixel receives reflected or transmitted light from the read document. A light-blocking member that blocks light so as not to occur, and a gate that generates a gate signal including a shift pulse that simultaneously shifts the charges generated by the plurality of light-receiving elements from each light-receiving element to the transfer register A plurality of signals having different phases applied to the transfer register so that the charge shifted from the light receiving element to the transfer register by the shift pulse is transferred to the output unit in the transfer register. Driving pulse signal generating means for generating the driving pulse signal. Furthermore, in the present invention, the output signal output from the output unit when the light source irradiates the read original corresponds to the charge shifted from the light receiving element to the transfer register by a shift pulse. Correction value deriving means for deriving a correction value of an output signal based on a signal level of a light-shielding portion related to an effective pixel light-shielded by the light-shielding member, and the light source irradiates the read original with light. The correction value derived by the correction value deriving means is subtracted from the signal level of the effective portion of the pixel portion that is not shielded by the light shielding member in the output signal output from the output unit. Correction means.

  According to this configuration, the correction value derived based on the signal level of the light shielding portion is independent of noise peculiar to the optical black pixel due to temperature fluctuation or infrared light incidence. Therefore, it is possible to sufficiently reduce smear by correcting the output signal using the correction value. The correction value derived based on the signal level of the light shielding part incorporates noise components other than smear such as dark current and circuit system drift in the transfer register. Therefore, by correcting the output signal using such a correction value, it is possible to sufficiently reduce noise components other than smear.

  The image reading apparatus of the present invention further includes a lens that forms an image displayed on the read original on the light receiving element, and the light shielding member is on the opposite side of the lens from the solid-state imaging element. It is preferable to arrange | position. According to this configuration, the influence of lens flare can be eliminated.

  The image reading apparatus according to the present invention includes an adjustment value storage unit that stores an adjustment value for adjusting a signal level of an output signal, and an adjustment stored in the adjustment value storage unit so that the signal level of the light-shielding portion becomes a specified value. It is preferable to further include adjustment value changing means for rewriting the value. According to this configuration, the influence of dark current in the light receiving element can be eliminated.

  In the image reading apparatus of the present invention, the correction value deriving unit may include a reference value subtracting unit that subtracts a reference value from the signal level of the light shielding portion. According to this configuration, it is possible to correct offset level fluctuations due to temperature changes and changes with time.

  In the image reading apparatus according to the aspect of the invention, it is preferable that the correction value deriving unit includes a first average value deriving unit that derives an average value of signal levels in one light shielding portion. According to this configuration, the accuracy of the correction value is improved.

  In the image reading apparatus of the present invention, the correction value deriving unit includes a second average value deriving unit for deriving an average value of the signal levels of the plurality of light shielding portions related to a plurality of continuous shift pulses. Is preferred. According to this configuration, the accuracy of the correction value is further improved.

  In the image reading apparatus of the present invention, the solid-state imaging device includes a plurality of transfer registers, the correction value deriving unit derives a correction value for each of the plurality of transfer registers, and the correction unit includes: A corresponding correction value may be subtracted from the signal level of the effective portion. According to this configuration, the same output signal can be obtained from a plurality of transfer registers.

  The image reading apparatus of the present invention preferably further comprises monitoring means for monitoring whether or not the signal level of the light shielding portion is within a predetermined range. According to this configuration, the black level can be monitored without the light receiving element not receiving light by turning off the light source or arranging the light shielding member.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a photographic processing apparatus provided with a film scanner according to an embodiment of the present invention.

  As shown in FIG. 1, a photographic processing apparatus 1 controls a film scanner 10 that optically reads a frame image recorded on a developed photographic film 65 and outputs a digital image signal, and the entire photographic processing apparatus 1. And a printing apparatus 50 that forms an image on photographic paper based on an image signal output from the film scanner 10. The control device 40 displays various information related to the photo processing device 1 and notifies the operator, and input devices such as a keyboard 62 and a mouse 63 for giving instructions to the photo processing device 1 by the operator. Is connected.

  The film scanner 10 includes a halogen lamp 11, a light control filter 12 for adjusting the color balance of light emitted from the halogen lamp 11, a mirror tunnel 13 that uniformly mixes the light that has passed through the light control filter 12, and a photograph A film transport mechanism 14 for sequentially causing each frame image of the film 65 and the halogen lamp 11 to face each other, a CCD line sensor unit 15 for photoelectrically converting the frame image of the photographic film 65, and light transmitted through the photographic film 65 as a CCD line A lens 16 for forming an image on the sensor unit 15, a mirror 17 for bending the optical path by 90 degrees, an amplifier 18 for amplifying an analog output signal of the CCD line sensor unit 15, and an amplifier 18 An A / D converter 19 for converting an analog signal into a digital signal; And an output signal processing unit 20 for processing the signal converted into a digital signal by the converter 19.

  The CCD line sensor unit 15 has three CCD line sensors 70 respectively corresponding to three colors of R (red), G (green), and B (blue) arranged in three rows. Here, the configuration of the CCD line sensor 70 will be described with reference to FIG. FIG. 2 is a diagram showing a schematic configuration of the CCD line sensor 70.

  As shown in FIG. 2, the CCD line sensor 70 includes a light receiving element 71 such as a photodiode that generates approximately 5000 charges arranged in the width direction of the photographic film 65, and a light receiving element 71. A transfer register 72 that transfers the charges generated in step S1 in parallel to the arrangement direction of the light receiving elements 71, and an output unit 74 that outputs an output signal having a signal level corresponding to the amount of charges transferred from the transfer register 72. Yes.

  On the light receiving surface of the light receiving elements 71 arranged in a line, a red color filter is formed on the sensor corresponding to R, a green color filter is formed on the sensor corresponding to G, and a blue color filter is formed on the sensor corresponding to B. (Not shown). The plurality of light receiving elements 71 include black pixels covered with a light shielding film made of metal such as aluminum (not shown), invalid pixels that are not used for image formation in the printing apparatus 50, and image formation in the printing apparatus 50. Effective pixels. With such a configuration, the frame image of the photographic film 65 can be color-separated and detected by the three CCD line sensors 70 respectively corresponding to R, G, and B.

  Next, the output signal processing unit 20 will be described with reference to FIG. FIG. 3 is a block diagram of the output signal processing unit 20. As shown in FIG. 3, the output signal processing unit 20 includes a gate signal generation unit 21, a drive pulse signal generation unit 22, an effective pixel memory 23, a register memory 24, an adjustment value storage unit 25, and an adjustment value change. A unit 26, a correction value deriving unit 27, a correcting unit 28, a monitoring unit 29, a black level flattening processing unit 30, and a shading processing unit 31.

  The gate signal generation unit 21 generates a gate signal ΦTG (see FIG. 4) including a shift pulse for shifting charges generated in the plurality of light receiving elements 71 from the respective light receiving elements 71 to the transfer register 72.

  The drive pulse signal generation unit 22 transfers the charge shifted from the light receiving element 71 to the transfer register 72 by the shift pulse, toward the output unit 74 in the transfer register 72, and transfers the charge from the light receiving element 71 to the transfer register by the shift pulse. The charge is transferred to the output unit 74 in the transfer register 72 during a period A from when all the charges shifted to 72 reach the output unit 74 until the next shift pulse shifts the charge from the light receiving element 71 to the transfer register 72. The two drive pulse signals Φ1 and Φ2 having opposite phases applied to the transfer register 72 and the drive pulse signal Φ1L having the same phase as the drive pulse signal Φ1 are generated (see FIG. 4). ).

  Here, an output signal output from the output unit 74 of the CCD line sensor 70 will be described with reference to FIG. 4 which is a timing chart of signals related to the CCD line sensor 70. First, at time t <b> 0 to t <b> 1, the charges generated in the plurality of light receiving elements 71 are shifted from each light receiving element 71 to the transfer register 72 by the shift pulse of the gate signal ΦTG. Thereafter, at time t1 to t8, the drive pulse signals Φ1, Φ2, and Φ1L are applied to the transfer register 72, and the charge shifted from the light receiving element 71 to the transfer register 72 is transferred to the output unit 74 in the transfer register 72. Is done. At this time, an output signal is output from the output unit 74. In the present embodiment, it is assumed that the halogen lamp 11 irradiates the photographic film 65 with light while a signal is output from the output unit 74.

  Of the output signals output from the output unit 74, the signals output at times t2 to t6 are portions corresponding to the charges shifted from the light receiving element 71 to the transfer register 72 by the shift pulse (hereinafter referred to as “pixel portions”). Called). Specifically, the signal output at time t2 to t3 is a portion related to a black pixel, and the signal output at time t3 to t4 and time t5 to t6 is a portion related to an invalid pixel, and time t4 to t5 The signal output at is the portion related to the effective pixel (hereinafter referred to as “effective portion”).

  On the other hand, signals output at time t1 to t2 and time t6 to t8 are portions other than the pixel portion (hereinafter referred to as “non-pixel portion”). Here, in the transfer register 72, in order to output all the charges shifted from the light receiving element 71 at once by the shift pulse from the output unit 74, a predetermined number of idle transfers (hereinafter referred to as “necessary idle transfer”). is required. The signals output at time t1 to t2 and time t6 to t7 are portions related to this necessary empty transfer. Further, in the present embodiment, in the transfer register 72, all the charges shifted from the light receiving element 71 by the shift pulse at one time are output from the output unit 74, and after the necessary transfer is completed, additional empty transfer (hereinafter referred to as “empty transfer”) is performed. , Referred to as “additional empty transfer”). Signals output at times t7 to t8 are portions related to this additional empty transfer.

  In the present embodiment, as will be described later, the correction value Sd is derived using the average value Ave_Rd of the signal level of the non-pixel portion corresponding to the period A following the pixel portion. Therefore, the correction value Sd can be stabilized by increasing the number of additional empty transfers in the transfer register 72. As the number of transfers in the transfer register 72 increases, the absolute value of smear decreases. Therefore, the resolution of the output image can be improved by increasing the number of additional empty transfers.

  As described above, the CCD line sensor 70 performs processing for one line at times t0 to t8. The CCD line sensor 70 repeats such processing a plurality of times, and reads the frame image of the photographic film 65 line by line.

  Returning to FIG. 3, the effective pixel memory 23 stores the signal level Pd of the effective portion of the output signal output from the output unit 74 of the CCD line sensor 70. The register memory 24 outputs the signal level Rd of the non-pixel portion in the output signal output from the output unit 74 of the CCD line sensor 70, the portion following the pixel portion, that is, the portion corresponding to the period A (see FIG. 4). Remember.

  The adjustment value storage unit 25 stores an adjustment value for adjusting the output signal output from the output unit 74 of the CCD line sensor 70. The adjustment value changing unit 26 rewrites the adjustment value stored in the adjustment value storage unit 25 so that the signal level of the non-pixel portion of the output signal output from the output unit 74 becomes the specified value Ref_Bk that is the black reference. .

  The correction value deriving unit 27 is a noise component such as smear included in the signal level Pd of the effective portion based on the signal level Rd corresponding to the period A among the output signals output from the output unit 74 of the CCD line sensor 70. A correction value Sd for reducing the above is derived. The correction value deriving unit 27 includes a first average value deriving unit 27a, a second average value deriving unit 27b, and a reference value subtracting unit 27c.

  The first average value deriving unit 27a derives the average value Ave0_Rd of the signal level within the period A. The second average value deriving unit 27b calculates the signal level average value Ave0_Rd within the period A derived by the first average value deriving unit 27a and the pixel portion in the processing for one line performed immediately before. The average value Ave_Rd with the average value Ave0_Rd ′ of the signal level within the period A ′, which is a subsequent portion, is derived. The reference value subtraction unit 27c derives a correction value Sd (= Ave_Rd−Ref_Rd) by subtracting the reference value Ref_Rd that is an offset level from the average value Ave_Rd derived by the second average value deriving unit 27b.

  The correction unit 28 subtracts the correction value Sd derived by the correction value deriving unit 27 from the signal level Pd of the effective portion of the output signal output from the output unit 74 of the CCD line sensor 70.

  The monitoring unit 29 monitors whether or not the signal level Rd of the period A is within a predetermined range among the output signals output from the output unit 74 of the CCD line sensor 70. The predetermined range is an allowable range determined based on the specified value Ref_Bk that is a black reference. In the present embodiment, when the signal level Rd in the period A exceeds the predetermined range, a warning message that informs the operator of the fact is displayed on the display 61. When the signal level Rd in the period A exceeds a predetermined range, the output stored in the adjustment value storage unit 25 so that the signal level of the non-pixel portion becomes the specified value Ref_Bk by the adjustment value changing unit 26. The adjustment value of the signal may be automatically rewritten.

  The black level flattening processing unit 30 performs black level flattening processing for removing dark current in the light receiving element 71 from the signal corrected by the correction unit 28. The dark current is noise generated because charges are accumulated in the light receiving element 71 even in a dark state where light is not received. Since the magnitude of the dark current varies from one light receiving element 71 to another, it causes unevenness that occurs in the sub-scanning direction of the output image. In the shading processing unit 31, shading for correcting the illuminance variation of the halogen lamp 11 in the main scanning direction that is the arrangement direction of the light receiving elements 71 and the temporal change of the light amount with respect to the signal processed in the black level flattening processing unit 30. Processing is performed.

  With the configuration as described above, in the film scanner 10, when the photographic film 65 is set in the film transport mechanism 14, the frame images on the photographic film 65 transported by the transport roller pair 14a are sequentially read in red, green, The digital image signal for each blue color is processed by the output signal processing unit 20 and then transmitted to the control device 30.

  Next, the processing procedure for one line performed by the film scanner 10 will be described with reference to FIGS. 4 and 5. FIG. 5 is a flowchart showing a procedure of processing for one line performed by the film scanner 10.

  First, the adjustment value changing unit 26 rewrites the adjustment value stored in the adjustment value storage unit 25 so that the signal level corresponding to the non-pixel portion output from the CCD line sensor 70 becomes the specified value Ref_Bk. Then, the black level is adjusted (step S101). Next, a plurality of light receiving elements 71 arranged in a line receive light emitted from the halogen lamp 11 and transmitted through the photographic film 65 (step S102: t <t0). At this time, in the light receiving element 71, an amount of electric charge corresponding to the amount of received light is generated and accumulated therein. Thereafter, the charge generated in each light receiving element 71 is shifted to the transfer register 72 by the shift pulse of the gate signal ΦTG generated by the gate signal generation unit 21 (step S103: t0 <t <t1).

  Then, the drive pulse signals Φ1, Φ2, and Φ1L generated by the drive pulse signal generation unit 22 are applied to the transfer register 71, and the charge is transferred to the output unit 74 by one pulse in the transfer register 72 (step) S104). At this time, a signal for one pulse is output from the output unit 74, and it is determined whether or not the signal output from the output unit 74 is a signal corresponding to an effective portion (step S105). When it is determined that the signal corresponds to the effective portion (step S105: YES: t4 <t <t5), the signal level Pd output from the output unit 74 is stored in the effective pixel memory 23 (step S106). ). Thereafter, steps S107 to S110 described later are omitted, and the process proceeds to step S111.

  On the other hand, when it is determined that the signal output from the output unit 74 is not a signal corresponding to the effective portion (step S105: NO), the signal corresponds to the period A following the pixel portion of the non-pixel portion. Is determined (step S107). When it is determined that the signal does not correspond to the period A (step S107: NO), steps S108 to S110 described later are omitted, and the process proceeds to step S111.

  When it is determined that the signal corresponds to the period A (step S107: YES: t6 <t <t8), the signal level Rd output from the output unit 74 is stored in the register memory 24 (step S107). S108). Further, the monitoring unit 29 determines whether or not the signal level Rd of the period A is within a predetermined range (step S109). When it is determined that the signal level Rd of the period A is within the predetermined range (step S109: YES), step S110 described later is omitted and the process proceeds to step S111. On the other hand, when it is determined that the signal level Rd of the period A is not within the predetermined range (step S109: NO), a warning message indicating that fact to the operator is displayed on the display 61 (step S110). At this time, the operator performs an operation so that the black level is adjusted again in step S101 as necessary.

  Thereafter, it is determined whether or not the transfer of the charges by the drive pulse signals Φ1, Φ2, and Φ1L in the transfer register 72 is completed (step S111). If it is determined that the charge transfer in the transfer register 72 has not been completed (step S111: NO: t1 <t <t8), the process returns to step S104, and the transfer register 72 outputs the charge for one pulse again. The signal is transferred to the unit 74, and a signal for one pulse is output from the output unit 74. On the other hand, when it is determined that the charge transfer in the transfer register 72 has ended (step S111: YES: t = t8), the first average value deriving unit 27a stores the period A stored in the register memory 24. The average value Ave0_Rd of the signal level Rd is derived (step S112).

  Then, the second average value deriving unit 27b corresponds to the average value Ave0_Rd of the signal level in the period A derived by the first average value deriving unit 27a and the period A ′ of the output signal for the immediately preceding one line. The average value Ave_Rd with the average value Ave0_Rd ′ of the signal level of the portion to be calculated is derived. Further, the reference value subtraction unit 27c derives the correction value Sd by subtracting the reference value Ref_Rd from the average value Ave_Rd derived by the second average value deriving unit 27b (step S113).

  Thereafter, the correction unit 28 subtracts the correction value Sd derived in step S113 from the signal level Pd of the effective portion stored in the effective pixel memory 23 (step S114). Then, the black level flattening processing unit 30 performs black level flattening processing on the signal corrected in step S114 (step S115). Further, the shading processor 31 performs a shading process on the signal processed in step S115 (step S116).

  In this embodiment, the black level flattening process performed in step S115 may be performed before the correction in step S114 is performed.

  As described above, in the film scanner 10 of the present embodiment, the correction value deriving unit 27 outputs the signal output from the output unit 74 of the transfer register 72 during the period A, which is a non-pixel portion following the pixel portion. A correction value Sd is derived based on the corresponding signal level Rd. The correction value Sd derived in this way is irrelevant to noise peculiar to the black pixel due to temperature fluctuation or infrared light incidence. Therefore, the correction unit 28 can sufficiently reduce smear by correcting the signal level Pd of the effective portion using the correction value Sd. The correction value Sd incorporates noise components other than smear such as dark current and circuit system drift in the transfer register 72. As a result, the correction unit 28 can sufficiently reduce noise components other than smear by correcting the signal level Pd of the effective portion using the correction value Sd.

  Further, in the film scanner 10 of the present embodiment, the adjustment value changing unit 26 adjusts so that the signal level of the non-pixel portion of the output signal output from the output unit 74 becomes the specified value Ref_Bk that is the black reference. The adjustment value stored in the value storage unit 25 is rewritten. Therefore, the influence of the dark current in the light receiving element 71 can be eliminated.

  Further, in the film scanner 10 according to the present embodiment, the reference value subtracting unit 27c subtracts the reference value Ref_Rd that is an offset level from the average value Ave_Rd derived by the second average value deriving unit 27b. Sd (= Ave_Rd−Ref_Rd) is derived. Therefore, it is possible to correct offset level fluctuations due to temperature changes and changes with time.

  In addition, in the film scanner 10 of the present embodiment, the first average value deriving unit 27a derives the average value Ave0_Rd of the signal level Rd within the period A among the output signals output from the output unit 74. Further, the second average value deriving unit 27b performs pixel processing in the average value Ave0_Rd of the signal level in the period A derived by the first average value deriving unit 27a and the processing for one line performed immediately before. An average value Ave_Rd with respect to the average value Ave0_Rd ′ of the signal level in the period A ′ that is a part subsequent to the part is derived. Therefore, the accuracy of the correction value Sd is improved.

  In the film scanner 10 of the present embodiment, the monitoring unit 29 monitors whether or not the signal level Rd in the period A following the pixel portion of the non-pixel portion is within a predetermined range. Accordingly, the black level can be monitored without the light receiving element 71 not receiving light by turning off the halogen lamp 11 or arranging the light shielding member.

  Next, a second embodiment of the present invention will be described. The photographic processing apparatus provided with the film scanner 110 according to the second embodiment of the present invention is mainly different from the photographic processing apparatus 1 of the first embodiment in that the film scanner 10 of the first embodiment. The output signal processing unit 20 derives the correction value Sd based on the signal level Rd of the period A following the pixel portion which is the non-pixel portion of the output signal output from the output unit 74. The output signal processing unit 120 of the film scanner 110 according to the embodiment is that a correction value Sd is derived based on a signal level Rd of a light shielding portion described later among output signals output from the output unit 174. The remaining configuration of the photographic processing apparatus of the second embodiment is substantially the same as that of the first embodiment, and a detailed description thereof is omitted.

  FIG. 6 is a diagram illustrating a schematic configuration of the film scanner 110 according to the second embodiment. In FIG. 6, a light control filter, a mirror tunnel, a film transport mechanism, a mirror, an amplifier, an A / D converter, and an output signal processing unit 120 provided in the film scanner 110 are described. Is omitted. In addition, the optical path which is originally bent 90 degrees by the mirror is drawn without being refracted. As shown in FIG. 6, in the film scanner 110 of the present embodiment, a light shielding member 135 is disposed between the halogen lamp 111 and the photographic film 165 so as to block a part of the light emitted from the halogen lamp 111. ing. Accordingly, among the light receiving elements 171 arranged in a single direction, the light emitted from the halogen lamp 111 is not irradiated to the light receiving elements 171 located in the region Z shown in FIG.

  Next, the output signal processing unit 120 of the present embodiment will be described with reference to FIG. FIG. 7 is a block diagram of the output signal processing unit 120. As illustrated in FIG. 7, the output signal processing unit 120 includes a gate signal generation unit 121, a drive pulse signal generation unit 122, an irradiation pixel memory 123, a light-shielded pixel memory 124, an adjustment value storage unit 125, and an adjustment value. A changing unit 126, a correction value deriving unit 127, a correcting unit 128, a monitoring unit 129, a black level flattening processing unit 130, and a shading processing unit 131 are included.

  Here, the functions of the gate signal generation unit 121, the adjustment value storage unit 125, the black level flattening processing unit 130, and the shading processing unit 131 of the present embodiment are the same as those of the gate signal generation unit 21 of the first embodiment. Since the functions of the value storage unit 25, the black level flattening processing unit 30, and the shading processing unit 31 are the same, description thereof will be omitted.

  In the drive pulse signal generation unit 122, the charges shifted from the light receiving element 171 to the transfer register 172 by the shift pulse of the gate signal ΦTG are transferred to the output unit 174 in the transfer register 172, and are all output from the output unit 174. As described above, two drive pulse signals Φ1 and Φ2 having opposite phases to each other applied to the transfer register 72 and a drive pulse signal Φ1L having the same phase as the drive pulse signal Φ1 are generated.

  Here, an output signal output from the output unit 174 of the CCD line sensor 170 will be described with reference to FIG. 8 which is a timing chart of signals related to the CCD line sensor 170. First, at time t <b> 0 to t <b> 1, charges generated in the plurality of light receiving elements 171 are shifted to the transfer register 172 by the shift pulse of the gate signal ΦTG. Thereafter, at time t <b> 1 to t <b> 8, the drive pulse signals Φ <b> 1, Φ <b> 2, and Φ <b> 1 </ b> L are applied to the transfer register 172. At this time, an output signal is output from the output unit 174. In this embodiment, it is assumed that the halogen lamp 111 irradiates the photographic film 165 with light while a signal is output from the output unit 174.

  Of the output signals output from the output unit 174, signals output at times t2 to t7 are pixel portions. Specifically, the signal output at time t2 to t3 is a portion related to a black pixel, and the signal output at time t3 to t4 and time t6 to t7 is a portion related to an invalid pixel, and time t4 to t5 The signal output at is a portion related to the irradiation pixel irradiated with the light emitted from the halogen lamp 111 among the effective pixels (hereinafter referred to as “irradiation portion”), and the signal output at time t5 to t6 is This is a portion related to a light-shielded pixel that is not irradiated with light emitted from the halogen lamp 111 among the effective pixels (hereinafter referred to as “light-shielded portion”). On the other hand, signals output at time t1 to t2 and time t7 to t8 are non-pixel portions related to necessary empty transfer.

  Returning to FIG. 7, the irradiation pixel memory 123 stores the signal level Pd of the effective portion of the output signal output from the output unit 174. The light shielding pixel memory 124 stores the signal level Rd of the light shielding portion in the output signal output from the output unit 174.

  The adjustment value changing unit 126 rewrites the adjustment value stored in the adjustment value storage unit 125 so that the signal level Rd of the light shielding portion of the output signal output from the output unit 174 becomes the specified value Ref_Bk that is the black reference. .

  The correction value deriving unit 127 reduces a noise component such as smear included in the signal level Pd of the effective portion based on the signal level Rd of the light shielding portion of the output signal output from the output unit 174. Is derived. The correction value deriving unit 127 includes a first average value deriving unit 127a, a second average value deriving unit 127b, and a reference value subtracting unit 127c.

  The first average value deriving unit 127a derives an average value Ave0_Rd of the signal level in the light shielding portion. The second average value deriving unit 27b calculates the signal level average value Ave0_Rd derived from the first average value deriving unit 27a and the signal in the light-shielding part in the process for one line performed immediately before. An average value Ave_Rd with the average value Ave0_Rd ′ of the level is derived. The reference value subtraction unit 127c derives a correction value Sd (= Ave_Rd−Ref_Rd) by subtracting the reference value Ref_Rd that is an offset level from the average value Ave_Rd derived by the second average value deriving unit 127b.

  The correction unit 128 subtracts the correction value Sd derived by the correction value deriving unit 127 from the signal level Pd of the effective portion of the output signal output from the output unit 174 of the CCD line sensor 170.

  The monitoring unit 129 monitors whether or not the signal level Rd related to the light-shielding portion of the output signal output from the output unit 174 is within a predetermined range determined based on the specified value Ref_Bk that is the black reference. In the present embodiment, when the signal level Rd related to the light-shielding portion exceeds a predetermined range, a warning message that informs the operator to that effect is displayed on the display. It should be noted that when the signal level Rd related to the light shielding portion exceeds a predetermined range, the adjustment value changing unit 126 outputs the output stored in the adjustment value storage unit 125 so that the signal level of the light shielding portion becomes the specified value Ref_Bk. The adjustment value of the signal may be automatically rewritten.

  Next, a processing procedure for one line performed by the film scanner 110 will be described with reference to FIGS. 8 and 9. FIG. 9 is a flowchart showing a procedure of processing for one line performed by the film scanner 110.

  First, the adjustment value changing unit 126 rewrites the adjustment value stored in the adjustment value storage unit 125 so that the signal level corresponding to the light shielding portion output from the CCD line sensor 170 becomes the specified value Ref_Bk. The black level is adjusted (step S201). Next, the plurality of light receiving elements 171 arranged in a line receive the light emitted from the halogen lamp 111 and transmitted through the photographic film 165 (step S202: t <t0). At this time, in the light receiving element 171 corresponding to the irradiated pixel, an amount of electric charge corresponding to the amount of received light is generated and accumulated therein. Thereafter, the charge generated in each light receiving element 171 is shifted to the transfer register 172 by the shift pulse of the gate signal ΦTG generated by the gate signal generation unit 121 (step S203: t0 <t <t1).

  Then, the drive pulse signals Φ1, Φ2, and Φ1L generated by the drive pulse signal generation unit 122 are applied to the transfer register 172, and the charge is transferred by one pulse toward the output unit 174 in the transfer register 172 (step). S204). At this time, a signal for one pulse is output from the output unit 174, and it is determined whether or not the signal output from the output unit 174 is a signal corresponding to the irradiated portion (step S205). When it is determined that the signal corresponds to the irradiated portion (step S205: YES: t4 <t <t5), the signal level Pd output from the output unit 174 is stored in the irradiated pixel memory 123 (step S206). ). Thereafter, steps S207 to S210 described later are omitted, and the process proceeds to step S211.

  On the other hand, when it is determined that the signal output from the output unit 174 is not a signal corresponding to the irradiated portion (step S205: NO), it is determined whether or not the signal is a signal corresponding to the light shielding portion (step S207). ). If it is determined that the signal does not correspond to the light-shielding portion (step S207: NO), steps S208 to S210 described later are omitted, and the process proceeds to step S211.

  If it is determined that the signal corresponds to the light shielding portion (step S207: YES: t5 <t <t6), the signal level Rd output from the output unit 174 is stored in the light shielding pixel memory 124 ( Step S208). Further, the monitoring unit 129 determines whether or not the signal level Rd of the light shielding portion is within a predetermined range (step S209). When it is determined that the signal level Rd of the light shielding portion is within the predetermined range (step S209: YES), step S210 described later is omitted and the process proceeds to step S211. On the other hand, when it is determined that the signal level Rd of the light-shielding portion is not within the predetermined range (step S209: NO), a warning message to that effect is displayed on the display (step S210). At this time, the operator performs an operation so that the black level is adjusted again in step S201 as necessary.

  Thereafter, it is determined whether or not the transfer of charges by the drive pulse signals Φ1, Φ2, and Φ1L in the transfer register 172 has been completed (step S211). If it is determined that the charge transfer in the transfer register 172 has not ended (step S211: NO: t1 <t <t8), the process returns to step S204, and the transfer register 172 outputs the charge for one pulse again. The signal is transferred to the unit 174 and a signal for one pulse is output from the output unit 174. On the other hand, when it is determined that the charge transfer in the transfer register 172 has been completed (step S211: YES: t = t8), the light shielding pixel stored in the light shielding pixel memory 124 by the first average value deriving unit 127a. An average value Ave0_Rd of the pixel signal level Rd is derived (step S212).

  Then, the second average value deriving unit 127b corresponds to the light shielding part of the signal level average value Ave0_Rd derived by the first average value deriving part 127a and the output signal for the immediately preceding one line. The average value Ave_Rd with the average value Ave0_Rd ′ of the signal level of the part is derived. Further, the reference value subtraction unit 127c derives the correction value Sd by subtracting the reference value Ref_Rd from the average value Ave_Rd derived by the second average value deriving unit 127b (step S213).

  Thereafter, the correction unit 128 subtracts the correction value Sd derived in step S213 from the signal level Pd of the irradiated portion stored in the irradiation pixel memory 123 (step S214). Then, the black level flattening processing unit 130 performs black level flattening processing on the signal corrected in step S214 (step S215). Further, the shading processing unit 131 performs a shading process on the signal processed in step S215 (step S216).

  In this embodiment, the black level flattening process performed in step S215 may be performed before the correction in step S214 is performed.

  As described above, in the film scanner 110 according to the second embodiment, it is possible to sufficiently reduce smear similarly to the film scanner 10 according to the first embodiment.

  In the film scanner 110 according to the second embodiment, the correction value deriving unit 127 is shielded from the output signal from the output unit 174 by the light shielding member 135 disposed between the halogen lamp 111 and the lens 116. The correction value Sd is derived based on the signal level Rd of the light shielding portion corresponding to the light shielding pixel. Therefore, the influence of lens flare can be eliminated.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims. Is.

  For example, FIG. 10 shows a modification according to the first embodiment. FIG. 10 is a diagram showing a schematic configuration of a CCD line sensor 270 according to this modification. As shown in FIG. 10, the CCD line sensor 270 according to this modification transfers a plurality of light receiving elements 271 arranged in one direction and charges generated by the light receiving elements 271 in parallel with the arrangement direction of the light receiving elements 271. First and second transfer registers 272 and 273, and first and second output units for outputting output signals having signal levels corresponding to the amounts of charges transferred from the first and second transfer registers 272 and 273 274, 275.

  Specifically, the charges generated by the odd-numbered light receiving elements 271 among the plurality of light receiving elements 271 arranged in a line are shifted to the first transfer register 272 by the shift pulse, and the first output unit 274 Forwarded towards. The electric charges generated in the light receiving elements 271 arranged in the even number are shifted to the second transfer register 273 by the shift pulse and transferred toward the second output unit 275.

  In this modification, the correction value deriving unit derives the correction values S1 and S2 for the first and second transfer registers 272 and 273, respectively, and the correcting unit includes the first and second output units 274, The corresponding correction value is subtracted from the signal levels Pd1 and Pd2 corresponding to the effective portion of the output signal from 275. Therefore, the same output signal can be obtained from the two transfer registers 272 and 273. The CCD line sensor 270 may be provided with three or more transfer registers.

  In the first embodiment, the correction value deriving unit 27 derives the correction value Sd based on the signal level Rd of the period A following the pixel portion of the non-pixel portion. However, the signal level of the portion preceding the pixel portion of the non-pixel portion may be used for deriving the correction value Sd.

  Furthermore, in the first and second embodiments described above, the adjustment value storage unit and the adjustment value change unit are included, and the adjustment value change unit is a non-pixel among the output signals output from the output unit. The case has been described where the adjustment value stored in the adjustment value storage unit is rewritten so that the signal level of the portion (the light shielding portion in the second embodiment) becomes the specified value Ref_Bk that is the black reference. I can't. The adjustment value storage unit and the adjustment value change unit may be omitted.

  In addition, in the above-described first and second embodiments, the correction value deriving unit includes the first average value deriving unit, the second average value deriving unit, and the reference value subtracting unit. The reference value subtraction unit derives the correction value Sd (= Ave_Rd−Ref_Rd) by subtracting the reference value Ref_Rd that is an offset level from the average value Ave_Rd derived by the second average value deriving unit. Although the case where the unit is provided has been described, the present invention is not limited to this. The reference value subtraction unit is not provided, and the average value Ave_Rd derived by the second average value deriving unit may be used as the correction value.

  In addition, in the average value Ave0_Rd of the signal level within the period A (the light shielding portion in the second embodiment) derived by the first average value deriving unit and the processing for one line performed immediately before, A second average value deriving unit for deriving an average value Ave_Rd with an average value Ave0_Rd ′ of the signal level within a period A ′ (a light shielding portion in the second embodiment) that is a portion subsequent to the pixel portion; Instead, the correction value may be derived based only on the average value Ave0_Rd of the signal level within the period A (the light shielding portion in the second embodiment). Further, the first average value deriving unit may not be provided, and the correction value may be derived based on only one signal level within the period A (the light shielding portion in the second embodiment).

  Furthermore, in the first and second embodiments described above, the monitoring unit sets the signal level Rd in the period A (light-shielded portion in the second embodiment) of the output signals output from the output unit to the black reference. Although the case where it is monitored whether or not it is within a predetermined range determined based on the specified value Ref_Bk is described, it is not limited to this. For example, the monitoring unit may monitor the signal level of an effective pixel (irradiated pixel in the second embodiment) that is not receiving light by turning off a halogen lamp or the like.

  In addition, in the above-described second embodiment, the case where the light shielding member 135 is disposed between the halogen lamp 111 and the lens 116 has been described, but the light shielding member 135 is separate from the CCD line sensor 170. It is sufficient that at least one of the plurality of light receiving elements 171 serving as an effective pixel is disposed so as not to receive the transmitted light from the photographic film 165.

  In the first and second embodiments described above, the film scanner that optically reads an image recorded on a photographic film has been described. However, the present invention is not limited to this. The present invention is generally applicable to an image reading apparatus that optically reads an image recorded on a read original.

1 is a diagram illustrating a schematic configuration of a photographic processing apparatus including a film scanner according to a first embodiment of the present invention. It is a figure which shows schematic structure of the CCD line sensor with which the CCD line sensor unit of FIG. 1 is equipped. FIG. 2 is a block diagram of an output processing unit shown in FIG. 1. 3 is a timing chart of signals related to the CCD line sensor shown in FIG. 2. It is a flowchart which shows the procedure of the process for 1 line performed with the film scanner shown in FIG. It is a figure which shows schematic structure of the film scanner which concerns on the 2nd Embodiment of this invention. FIG. 7 is a block diagram of an output signal processing unit provided in the film scanner shown in FIG. 6. 7 is a timing chart of signals related to the CCD line sensor shown in FIG. 6. It is a flowchart which shows the procedure of the process for 1 line performed with the film scanner of FIG. It is a modification which concerns on 1st Embodiment, and is a figure which shows schematic structure of a CCD line sensor.

Explanation of symbols

1 Photo processing device 10, 110 Film scanner (image reading device)
11, 111 Halogen lamp (light source)
15 CCD line sensor unit 16, 116 Lens 20, 120 Output signal processing unit 21, 121 Gate signal generation unit (gate signal generation means)
22, 122 Drive pulse signal generator (drive pulse signal generator)
25, 125 Adjustment value storage (adjustment value storage means)
26, 126 Adjustment value changing unit (adjustment value changing means)
27, 127 Correction value deriving unit (correction value deriving means)
27a, 127a First average value deriving unit (first average value deriving means)
27b, 127b Second average value deriving unit (second average value deriving means)
27c, 127c Reference value subtraction unit (reference value subtraction means)
28, 128 Correction unit (correction means)
29, 129 Monitoring unit (monitoring means)
65,165 Photo film (reading original)
70, 170, 270 CCD line sensor (solid-state imaging device)
71,171 Light receiving element 72,172,272,273 Transfer register 74,174,274,275 Output unit 135 Light shielding member

Claims (15)

A light source for irradiating the scanned document with light;
A plurality of light receiving elements arranged in one direction for receiving reflected light or transmitted light from the read original and generating an amount of charge corresponding to the amount of light received, and charges generated by the light receiving elements in parallel with the one direction A solid-state imaging device having a transfer register to transfer, and an output unit that outputs an output signal having a signal level corresponding to the amount of charge transferred from the transfer register;
Gate signal generating means for generating a gate signal including a shift pulse for simultaneously shifting charges generated in the plurality of light receiving elements from the respective light receiving elements to the transfer register;
The charge shifted from the light receiving element to the transfer register by the shift pulse is transferred to the output unit in the transfer register, and the charge shifted from the light receiving element to the transfer register by the shift pulse Charges are transferred toward the output unit in the transfer register during at least a part of the period from when the light reaches the output unit until the next shift pulse shifts the charge from the light receiving element to the transfer register. Drive pulse signal generating means for generating a plurality of drive pulse signals having different phases applied to the transfer register,
An output signal output from the output unit when the light source irradiates light on the read original, precedes or follows a pixel portion corresponding to a charge shifted from the light receiving element to the transfer register by a shift pulse. Correction value deriving means for deriving a correction value of the output signal based on the signal level of the non-pixel portion to be,
The correction derived by the correction value deriving means from the signal level of the effective portion of the pixel portion in the output signal output from the output unit when the light source irradiates the read original with light. An image reading apparatus comprising: a correction unit that subtracts a value. Adjustment value storage means for storing an adjustment value for adjusting the signal level of the output signal;
2. The image reading according to claim 1, further comprising adjustment value changing means for rewriting an adjustment value stored in the adjustment value storage means so that a signal level of the non-pixel portion becomes a specified value. apparatus.   The image reading apparatus according to claim 1, wherein the correction value deriving unit includes a reference value subtracting unit that subtracts a reference value from a signal level of the non-pixel portion.   The correction value deriving means includes first average value deriving means for deriving an average value of signal levels in one non-pixel portion. The image reading apparatus described in 1.   2. The correction value deriving means includes second average value deriving means for deriving an average value of signal levels of the plurality of non-pixel portions related to a plurality of consecutive shift pulses. The image reading device according to any one of? The solid-state imaging device includes a plurality of the transfer registers,
The correction value deriving means derives a correction value for each of the plurality of transfer registers;
The image reading apparatus according to claim 1, wherein the correction unit subtracts a corresponding correction value from the signal level of the effective portion.   The image reading apparatus according to claim 1, further comprising a monitoring unit that monitors whether a signal level of the non-pixel portion is within a predetermined range. A light source for irradiating the scanned document with light;
A plurality of light receiving elements arranged in one direction for receiving reflected light or transmitted light from the read original and generating an amount of charge corresponding to the amount of light received, and charges generated by the light receiving elements in parallel with the one direction A solid-state imaging device having a transfer register to transfer, and an output unit that outputs an output signal having a signal level corresponding to the amount of charge transferred from the transfer register;
A light-blocking member that is formed separately from the solid-state image sensor, and that blocks light so that at least one of the plurality of light-receiving elements that is an effective pixel does not receive reflected light or transmitted light from the read document;
Gate signal generating means for generating a gate signal including a shift pulse for simultaneously shifting charges generated in the plurality of light receiving elements from the respective light receiving elements to the transfer register;
A plurality of drive pulse signals having different phases applied to the transfer register are transferred so that the charge shifted from the light receiving element to the transfer register by the shift pulse is transferred to the output unit in the transfer register. Drive pulse signal generating means for generating;
In the output signal output from the output unit when the light source irradiates light on the read document, the light shielding is performed in the pixel portion corresponding to the electric charge shifted from the light receiving element to the transfer register by a shift pulse. Correction value deriving means for deriving a correction value of the output signal based on the signal level of the light shielding portion related to the effective pixel light-shielded by the member;
From the signal level of the effective portion related to the effective pixel that is not shielded by the light shielding member in the pixel portion in the output signal output from the output unit when the light source irradiates the reading document with light, An image reading apparatus comprising: correction means for subtracting the correction value derived by the correction value deriving means. A lens for imaging the image displayed on the read document on the light receiving element;
The image reading apparatus according to claim 8, wherein the light shielding member is disposed on a side opposite to the solid-state imaging device with respect to the lens. Adjustment value storage means for storing an adjustment value for adjusting the signal level of the output signal;
10. The image according to claim 8, further comprising adjustment value changing means for rewriting an adjustment value stored in the adjustment value storage means so that a signal level of the light shielding portion becomes a specified value. Reader.   The image reading apparatus according to claim 8, wherein the correction value deriving unit includes a reference value subtracting unit that subtracts a reference value from a signal level of the light shielding portion.   The correction value deriving unit includes a first average value deriving unit for deriving an average value of signal levels in one light-shielding portion. The image reading apparatus described.   9. The correction value deriving unit includes a second average value deriving unit for deriving an average value of signal levels of the plurality of light shielding portions related to a plurality of continuous shift pulses. The image reading apparatus according to any one of 12. The solid-state imaging device includes a plurality of the transfer registers,
The correction value deriving means derives a correction value for each of the plurality of transfer registers;
The image reading apparatus according to claim 8, wherein the correction unit subtracts a corresponding correction value from the signal level of the effective portion.   The image reading apparatus according to claim 8, further comprising a monitoring unit that monitors whether or not the signal level of the light shielding portion is within a predetermined range.

Images