JP4027573B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus such as an image scanner or a digital copying machine, and more specifically, determination of normal / abnormality of a system, determination of appropriateness of shading data, and ensuring of an appropriate level of black level data by detecting a peak of white level. The present invention relates to an image reading apparatus that performs such a control operation.
[0002]
[Prior art]
In the conventional image reading apparatus, it is determined whether the white level value is appropriate or whether the illumination system (lamp) is lit normally by detecting the white level. That is, conventionally, only the image processing unit is provided with a function of detecting a peak signal (maximum white level value) of the image data, and the white level falls within an appropriate range by feeding back the value to the amplifier of the reading unit. If the peak value is extremely small, it is determined that the lamp of the light source is not turned on, and error processing is performed.
[0003]
Further, in the conventional image reading apparatus, in order to eliminate the influence of dirt on the reference white plate for acquiring shading data and the influence of dust, the data up to the previous line in the same pixel is compared with the current data, and the difference between them is compared. When is larger than a certain value, it is determined that the current data is affected by dust and the like, and the current data is not adopted as the shading data. In this method, pixel data is subjected to a double addition averaging process when generating shading data to eliminate the influence of noise and the like.
[0004]
The averaged multiple addition data Sn-1 is compared with the newly sampled data Sn,
Sn-1−Sn = K
When the value of K is larger than the expected noise fluctuation, an abnormal value is determined, and Sn-1 is held as it is without adding Sn. In general, when the reference white plate 102 which is a shading plate is dirty or dusty, the read value becomes small. Therefore, when Sn is affected by dust,
Sn-1 ≧ Sn
It becomes the relationship.
[0005]
The CCD (Charge Coupled Device) has an optical black level output period called optical black. In the optical black period, the black level is acquired by shielding the light inside the CCD, and the output of the subsequent effective period becomes image data (white level). Therefore, the black level is included in the image data, and the black level is removed from the image data (subtracted as a digital calculation).
[0006]
Originally, it is only necessary to perform shading processing such as white level in a state where each effective pixel is shielded from light (illumination lamp OFF) and suppress variation in black level of each pixel (black shading). Scale and computing memory capacity increase. In addition, it is generally performed that the pixels within the period are averaged as a representative value because there is no problem even if the optical black period value is uniformly applied as a representative value due to the small variation due to the improvement of the CCD itself. Yes.
[0007]
[Problems to be solved by the invention]
However, in the conventional image reading apparatus as described above, the peak value is detected only on one side of the reading unit or the image processing unit, so that even if an abnormality occurs, it is accurately recognized. There is a problem in that it cannot be performed and incorrect adjustment is performed.
[0008]
In addition, in the conventional shading data acquisition, if the white level is incorrect due to some influence, for example, if the reference white plate is not read reliably or the gain of the amplifier is shifted, the shading data itself is meaningful. There was a possibility that it would disappear.
[0009]
Furthermore, in the past, the influence of noise has been eliminated by averaging the data of the sampled optical black output period of the CCD. There was a possibility that the influence could not be completely eliminated.
[0010]
The present invention has been made in view of the above, and by detecting the white level peak value on both sides of the reading unit and the image processing unit, it is possible to accurately determine the occurrence of an abnormality and accurately deal with post-processing. The first object is to perform it quickly.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, in the image reading apparatus according to claim 1, an original image to be read is optically imaged on an image sensor and read as image data, and read by the reading means. And an image processing unit that performs shading correction processing and MTF correction processing on the obtained image data. The image reading device is provided in the reading unit and read in the main scanning direction of the image data of the reference white plate read by the image sensor. First peak detection means for detecting a white level peak value for one line, and second peak detection provided in the image processing means for detecting a white level peak value for one line in the main scanning direction of the image data of the reference white plate And a white level peak value of the first peak detecting means and a white level peak value of the second peak detecting means. Determine the difference between them in the comparison result is within the allowable value, it is determined to be normal if the difference is within the allowable value, on the other hand, the said reading means if said difference is out of tolerance And an error processing means for executing error display on the assumption that any one of the peak detection means of the image processing means is abnormal or an abnormality has occurred in the mutual transmission path .
[0014]
According to the present invention, the white level peak value of one line in the main scanning direction of image data read by an image pickup device such as a CCD is obtained on both sides of the first peak detecting means of the reading means and the second peak detecting means of the image processing means. When the white level peak values detected by the two are compared, and the difference between the two is within the allowable value, it is determined to be normal. On the other hand, the difference is outside the allowable value. In addition, it is considered that an abnormality has occurred in one of the reading means and the peak detection means of the image processing means, or an abnormality has occurred in the transmission path between them, and an error display is executed, so that it is possible to accurately determine the occurrence of an abnormality. Become .
[0015]
In the image reading apparatus according to claim 2, the permissible value is such that a difference between the two in the comparison result is within a predetermined range , or a white level peak value in the comparison result is the same value . Is.
[0016]
According to the present invention, in claim 1, by setting in advance a predetermined range or the same value as an allowable value, and comparing the detected value of the white level peak value on the reading means side and the image processing means side with the allowable value, In the case of setting the same value, it is possible to determine whether any of the peak values is abnormal or whether there is an abnormality in the mutual transmission path. On the other hand, the difference depending on the detection method, for example, the reading means is one main scanning line. In the case where the peak value of the value averaged in the sub-scanning direction as in the shading data is detected, the error processing is performed by determining whether the peak value is within a predetermined range. .
[0017]
Further, in the image reading apparatus according to claim 3, wherein the error indication is for a display of abnormality and contact needed to service ku perform maintenance of the apparatus to the user of the device.
[0018]
According to the present invention, when error processing is executed when the white level peak value on both sides is not a predetermined allowable value in claim 1, the error processing includes display to the user and notification by voice, By making a notification such as telephone notification by a serviceman call or automatic communication to a service center, it is possible to respond quickly.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of an image reading apparatus according to the invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to this embodiment.
[0026]
FIG. 1 is a block diagram showing a configuration of an image reading apparatus according to an embodiment of the present invention. The image reading apparatus mainly includes an optical unit 100 having functional elements 101 to 105 described later, a reading unit 110 having functional elements 111 to 115 described later, and 121 to 125 described later. And an image processing unit 120 having the following functional elements.
[0027]
In the figure, reference numeral 101 is a contact glass for placing (setting) a document to be read, reference numeral 102 is a reference white plate serving as a reference for shading correction, reference numeral 103 is an illumination lamp for illuminating the original, and reference numeral 104 is a document or reference. A mirror for guiding the reflected light of the white plate 102 to the next lens, and a lens 105 for imaging the reflected light on the next CCD.
[0028]
Reference numeral 111 denotes a CCD (solid-state imaging device) that reads line by line, reference numeral 112 denotes an amplifier that adjusts the image data output from the CCD 111 to an appropriate white level, and reference numeral 113 denotes digital image data output from the amplifier 112. The A / D converter 114 converts the image data into the image data, and the reference numeral 114 denotes the drive of the CCD 111 and the A / D converter 113, the generation of the sampling signal, and the generation and setting of the control gate signal (setting of the reading width, etc.) accompanying the reading operation. A timing IC having a serial I / F function with each register, and a reference numeral 115 is a peak detection unit for detecting a white level peak value in one main scanning line of image data.
[0029]
Reference numeral 121 denotes an image processing IC that performs image processing such as shading correction (distortion correction), scanner gamma correction, and MTF correction on the image data, and reference numeral 122 detects a white level peak value in one main scanning line of the image data. A peak detection unit, reference numeral 123 denotes a CPU that executes various controls such as data acquisition processing and error processing according to the control program for the entire image processing unit 120, reference numeral 124 denotes a ROM that stores the control program, and reference numeral 125 denotes a control process in the middle of the CPU 123. This RAM is used as a working memory for storing data (including shading data).
[0030]
Next, the operation of the image reading apparatus configured as described above will be described. When the original reflected light from the optical unit 100 is imaged on the CCD 111, first, image data corresponding to the intensity of the reflected light is output from the CCD 111. The image data is adjusted to an appropriate white level by the amplifier 112 and then converted to digital image data by the A / D converter 113. Here, for example, it is converted into 8 bits (256 gradations). The converted image data is sent to the timing IC 114, and is synchronously transferred to the next-stage image processing unit 120 by the timing IC 114. At this time, the peak detector 115 detects a white level peak value (maximum white level) Y1 in one main scanning line of the image data.
[0031]
The image processing unit 120 performs image processing such as shading correction on the image data sent via the timing IC 114 and then transfers the image data to an external device such as a printer or a personal computer. Similarly to the reading unit 110, the peak detection unit 122 of the image processing unit 120 detects a white level peak value (maximum white level value) G1 in one main scanning line of image data.
[0032]
As described above, conventionally, only the image processing unit is provided with a function for detecting the peak signal (maximum white level value) of the image data, and the value is fed back to the amplifier of the reading unit, so that white Adjustment was made so that the level was in an appropriate range, or when this peak value was extremely small, it was determined that the lamp of the light source did not light, and error processing was performed. As described above, in the peak value detection of only one unit, even if an abnormality occurs, it cannot be accurately recognized, and erroneous adjustment is performed.
[0033]
Therefore, the present invention addresses this as follows. This operation will be described with reference to the flowchart shown in FIG. First, the image data read as described above is acquired (step S11), and the peak value Y1 of one main scanning line is detected by the peak detector 115 of the reading unit 110 (step S12). Subsequently, the image data is transferred to the image processing unit 120 (step S13), and the peak detection unit 122 of the image processing unit 120 detects the peak value G1 of one main scanning line (step S14).
[0034]
Subsequently, the peak value Y1 detected on the reading unit 110 side is compared with the peak value G1 detected on the image processing unit 120 side, and it is determined whether Y1 = G1 (step S15). If it is determined that Y1 = G1 is not satisfied, it is considered that an abnormality has occurred on any of the peak detection sides or an abnormality has occurred in the mutual transmission path, and a predetermined error control process is executed (step S16). ). This error process is a process of displaying an error occurrence on the operation panel (not shown) of the apparatus and notifying the user, or notifying the service area as a service man call.
[0035]
Practically, since the peak value is originally detected from the same read data, the peak values Y1 and G1 should be the same value. However, when there is a difference depending on the detection method, for example, when the reading unit 110 detects a peak of one main scanning line and the image processing unit 120 is a peak value of a value averaged in the sub-scanning direction like shading data. A slight difference occurs. In that case, it is determined whether or not the value of Y1−G1 = K is within the allowable range, and the peak values Y1 and G1 are not completely coincident (replaced in step S15). Therefore, error control may be executed.
[0036]
However, when compared with the operation of the flowchart of FIG. 2 described above, the determination accuracy is somewhat lowered. In addition, for example, when the LSB connection of image data is broken or short-circuited, it may not be detected.
[0037]
Conventionally, as described above, in order to eliminate the influence of dirt and dust on the reference white plate 102 which is a shading plate, the data up to the previous line in the same pixel and the current data are compared, and the difference When is larger than a certain value, it is determined that the current data is affected by dust and the like, and the current data is not adopted as the shading data. In this method, pixel data is subjected to a double addition averaging process when generating shading data to eliminate the influence of noise and the like.
[0038]
However, if the white level is wrong due to some influence, for example, if the reference white plate 102 is not read reliably or the gain of the amplifier is deviated, the shading data itself may become meaningless. Therefore, in the present invention, the peak value of each main scanning line is detected and a condition for determining whether or not the value is appropriate is added to ensure the accuracy of the shading data. This operation will be described below.
[0039]
FIG. 3 is a flowchart showing a procedure of shading correction processing according to the embodiment of the present invention. First, the peak value (Sn peak, Sn: pixel data for shading) of the main scanning line of the image data is detected (step S21). Subsequently, it is determined whether or not LSn peak ≧ T (step S22). Note that LSn peak is a peak value of each Sn in one main scanning line, and T is a predetermined allowable white level reference value.
[0040]
If it is determined in step S22 that LSn peak ≧ T (determination, Yes), it is further determined whether (ASn-1) −Sn <K (step S23). Note that ASn-1 is the double addition data, 1/4 × (3Sn-1 + Sn), and K is a predetermined allowable white level variation. Here, when it is determined that (ASn-1) -Sn <K (determination, Yes), Sn is added and averaged (step S24). On the other hand, if it is determined in step S22 that LSn peak ≧ T is not satisfied (determination, No), error processing is executed (step S25). This error process is a process of displaying an error occurrence on the operation panel (not shown) of the apparatus and notifying the user, or notifying the service area as a service man call.
[0041]
As described above, when the reference white plate 102 for shading is read, only when the maximum value of each main scanning line is larger than a predetermined value, it is adopted as shading data, so that an incorrect state, that is, a white level is obtained. It is possible to avoid the generation of shading data in a state where is abnormal, and to notify the user or service area of the state.
[0042]
By the way, the CCD 111 has a period for outputting an optical black level called optical black. The output state of the CCD 111 is shown in FIG. In the figure, a is a one-line output period, b is a dummy signal (for 72 pixels), c is an effective pixel signal (for 2928 pixels), d and f are each idle feed (for 12 pixels), and e is a light shield output (for 12 pixels). 48 pixels), that is, an optical black period (black level output period). That is, D0 to D71 indicate dummy signals, S1 to S2928 indicate valid data, and among the dummy signals, 48 pixels D12 to D59 are the optical black period.
[0043]
In the optical black period e, the black level is acquired by shielding the light inside the CCD 111, and the output in the subsequent effective period becomes image data (white level). Therefore, the black level is included in the image data, and the black level is removed from the image data (subtracted as a digital calculation).
[0044]
Further, as described above, originally, if each effective pixel is shielded from light (illumination lamp 103 OFF), shading processing such as white level is performed to suppress variation in black level of each pixel ( Black shading) is good, but the circuit scale and the calculation memory capacity increase. In addition, it is generally performed that the pixels within the period are averaged to be the representative value because there is no problem even if the optical black period e is uniformly applied as the representative value due to the small variation due to the improvement of the CCD itself. ing. However, when affected by external noise or the like, it is conceivable that the influence cannot be eliminated only by this averaging process.
[0045]
Therefore, in the present invention, when the variation within the optical black period e, for example, the difference between the maximum value and the minimum value is greater than or equal to a certain value, it is determined that the black level average of the main scanning line is not certain, and the previously used black The representative value of the level is used as a representative value as it is. Details will be described below.
[0046]
FIG. 5 is a block diagram showing the configuration of the black level adjustment portion of the image reading apparatus according to the embodiment of the present invention. In the figure, reference numeral 201 is a sample and hold amplifier that samples and holds odd pixels of the CCD 111, a reference numeral 202 is a sample and hold amplifier that samples and holds even pixels of the CCD 111, and reference numeral 203 is both sample hold amplifiers 201 and 202. Multiplexer that inputs and outputs either, reference numeral 204 is an amplifier that amplifies the output signal from the multiplexer 204, reference numeral 205 is an amplifier that adjusts the black level of the signal output from the amplifier 204, and reference numeral 206 is output from the amplifier 205. A / D converter that converts the signal to digital image data, 207 is a D / A converter, 208 is a background detection unit that detects the background (dirt) included in the image data, and 209 is fixed data. Fixed data output unit to output, reference numeral 210 is background detection 208 is a switch for supplying the reference fixed data output section 209, D / A converter 207 is switched each data output A / D converter 206.
[0047]
FIG. 6 is a flowchart showing black data acquisition processing according to the embodiment of the present invention. First, data is sampled during the optical black period e of the CCD 111 shown in FIG. 4 (step S31). Subsequently, the difference between the maximum value and the minimum value in the optical black period e is calculated (step S32). Subsequently, it is determined whether or not the difference between the maximum value and the minimum value is greater than or equal to a predetermined allowable value (step S33). If it is determined that the value is equal to or greater than the allowable value (Yes, determination), it is considered that the black level variation of the main scanning line is large (not sure), and the representative value of the optical black period e used last time is used as black data as it is. Used (step S34).
[0048]
That is, after sampling the data of the optical black period e, an averaging operation is performed and stored in the subtraction register. When the average value exceeds the allowable range, the black level of the previous line can be continuously used as the representative value by outputting a non-updatable disable signal to the subtraction register. Thereby, the influence of erroneous data due to noise in the black level information is eliminated, and appropriate image data can be obtained.
[0049]
【The invention's effect】
As described above, according to the image reading apparatus (claim 1) of the present invention, the white level peak value of one line in the main scanning direction of the image data read by the image pickup device such as a CCD is read by the reading means. Detected on both sides of the first peak detecting means and the second peak detecting means of the image processing means, the white level peak values detected by both are compared, and the result of the comparison is normal if the difference between them is within an allowable value On the other hand, if the difference deviates from the allowable value, it is considered that an error has occurred in any of the reading means and the peak detection means of the image processing means, or an abnormality has occurred in the mutual transmission path, and an error has occurred. for performing display, it is possible to accurately determine the abnormality between the reading means and the image processing unit each of the abnormality and both means, also be performed rapidly subsequent processing That.
[0050]
According to the image reading apparatus of the present invention (Claim 2), in Claim 1, the allowable value is set in advance as a predetermined range or the same value, and the white level peak values on the reading means side and the image processing means side are set. By comparing the detection value with the permissible value, in the case of setting the same value, it is determined whether there is an abnormality in any of the peak values or in the mutual transmission path. For example, when the reading means detects the peak value of one main scanning line and the image processing means is a peak value of a value averaged in the sub-scanning direction such as shading data, it is determined whether it is within a predetermined range. Therefore, accurate error processing based on the result can be performed.
[0051]
According to the image reading apparatus of the present invention (claim 3), when the error processing is executed when the white level peak value on both sides is not a predetermined allowable value in claim 1, the error processing is performed. As a notification to the user, notification by voice, telephone notification by serviceman call or automatic communication to the service center, work such as repairing abnormal parts proceeds quickly, and downtime of the image reading apparatus is shortened. can do.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an image reading apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a processing operation of white line peak value detection according to the embodiment of the present invention.
FIG. 3 is a flowchart showing an operation of a shading correction process according to the embodiment of the present invention.
FIG. 4 is an explanatory diagram showing an output state (timing) of a CCD.
FIG. 5 is a block diagram showing a configuration of a black level adjustment portion of the image reading apparatus according to the embodiment of the present invention.
FIG. 6 is a flowchart showing black data acquisition processing according to the embodiment of the present invention;
[Explanation of symbols]
100 Optical unit 102 Reference white plate 110 Reading unit 111 CCD
113 A / D converter 114 Timing IC
115, 122 Peak detector 120 Image processing IC
123 CPU
125 RAM

Claims (3)

A reading unit that optically forms an image of a document to be read on an image sensor and reads the image data as image data, and an image processing unit that adds shading correction processing and MTF correction processing to the image data read by the reading unit. In the image reading device,
A first peak detection unit that is provided in the reading unit and detects a white level peak value of one line in the main scanning direction of image data of a reference white plate read by the image sensor;
A second peak detecting means provided in the image processing means for detecting a white level peak value of one line in the main scanning direction of the image data of the reference white plate ;
The white level peak value of the first peak detecting means and the white level peak value of the second peak detecting means are compared, and it is determined whether the difference between the two in the comparison result falls within an allowable value. If it is within the value, it is judged as normal, while if the difference is outside the allowable value , either the reading means or the peak detection means of the image processing means is abnormal, or the mutual transmission path is abnormal. An error processing means for executing an error display ,
An image reading apparatus comprising: 2. The image reading apparatus according to claim 1, wherein the allowable value is such that a difference between the two in the comparison result is within a predetermined range or the white level peak value in the comparison result is the same value . The error display includes an image reading apparatus according to claim 1, characterized in that a display of the contact main to service ku performing maintenance abnormality and the device to the user of the device.

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