JPH09149251A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To previously prevent the deterioration of an optical system and the deterioration of quality owing to dust and a scan and to improve picture quality by judging shading correction precision based on picture data of a white reference member which is shading-corrected. SOLUTION: A system control part 21 lights a light source 45, scans a white reference board 44 for obtaining white reference data and stores picture data which is digitally converted in an A/D converter 50 in a line buffer 53 as white reference data. A system control part 21 scans again the white reference board 44 and calculates shading correction precision based on picture data at the time of scanning the white reference board 44. Whether the calculated result exceeds a correction precision judgment level or not is checked. When operated correction precision exceeds the correction judgment level, the system control part 21 judges that appropriate shading correction precision is obtained and shifts a processing to a regular read processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device, and more particularly, to an image reading device capable of appropriately determining shading correction accuracy and image quality.

[0002]

2. Description of the Related Art In an image reading apparatus, there are fluctuations in reading density due to changes in the amount of light emitted from a light source over time, fluctuations due to temperature rise, fluctuations in sensitivity of each pixel of a photoelectric conversion unit, etc. In order to prevent the deterioration of the image quality due to the above, conventionally, the white reference plate is scanned before the image of the original is read to acquire the white reference data, and the shading correction of the image of the original is performed based on the white reference data. Things are being done.

As a method for performing such shading correction, for example, a circuit for A / D converting an image signal obtained by scanning a photodetector array a plurality of times and accumulating and storing it for each pixel, An image input device that calculates a shading correction coefficient from the accumulated value and stores the shading correction coefficient, and obtains the shading correction coefficient with low noise and at high speed (see Japanese Patent Laid-Open No. 61-71764).
An image reading device for determining the life of the light source or the white reference plate by comparing the maximum value of the image signal obtained by scanning a plurality of lines of the white reference plate or the white reference plate with a preset threshold value.
3-1249), etc., and
When reading the brightness information on the reference plate, by moving the carriage on which the image sensor and the light source are placed at the same time when the image sensor is exposed to light, the effect of partial changes in reflectance on the reference plate A shading correction device (see Japanese Patent Laid-Open No. 1-132275) that suppresses the above has been proposed.

As described above, in the conventional image reading apparatus, how to make the shading coefficient low noise, determine the life of the light source or the white reference plate from the white reference data obtained by reading the white reference plate, or The purpose is to appropriately perform shading correction depending on how to reduce the influence of the partial reflectance when reading the white reference plate.

In the conventional shading correction, generally, as shown in the case of the facsimile apparatus 1 in FIG. 24, the light source 3 irradiates the white reference plate 4 with light to read the white reference plate 4 before reading the original 2. Data is acquired, and shading correction is performed based on this white reference data.

That is, in the facsimile apparatus 1, before the original 2 is read, the white reference plate 4 is irradiated from the light source 3 and the reflected light is introduced into the image sensor 7 via the mirror 5 and the lens 6 to form an image. It is photoelectrically converted by the sensor 7 and transferred to the A / D converter 9 via the amplifier 8. The peak hold circuit 10 detects and holds the maximum value of the image signal for one line input to the A / D converter 9,
The converter 9 quantizes the image signal that is amplified and input by the amplifier 8 based on the peak value detected and held by the peak hold circuit 10, and the shading correction circuit 11 is quantized.
And is stored as white reference data in the line buffer 13 via.

When the document 2 is read, the guide 14
The light from the light source 3 is radiated to the original 2 conveyed above,
Similarly to the above, the reflected light is introduced into the image sensor 7 via the mirror 5 and the lens 6, and the image signal photoelectrically converted by the image sensor 7 is transferred to the A / D converter 9 via the amplifier 8. At this time, the maximum value of the image signal for one line is detected by the peak hold circuit 10, quantized by the A / D converter 9 with the maximum value (peak value) as a reference, and output to the shading correction circuit 12.

The system control unit 1 sequentially associates the white reference data stored in the line buffer 13 when the white reference plate 4 is read with the image signal input from the A / D converter 9 for each pixel. Read out and shading correction circuit 1
2, the shading correction circuit 12 performs a predetermined shading correction calculation on the image signal input from the A / D converter 9 based on the white reference data, and outputs the image signal to the digital image processing circuit 16.

The digital image processing circuit 16 performs various kinds of image processing on the image signal whose distortion has been corrected.

Then, the conventional image reading apparatus such as the facsimile apparatus 1 reads the white reference plate 4 once before reading the original 2 and obtains white reference data, and then reads the original 2. The shading correction is performed on the image signal obtained by reading the original 2 based on the white reference data.

[0011]

However, in such a conventional image reading apparatus, shading correction is performed based on the white reference data obtained by scanning the white reference plate once before reading the document. However, since the accuracy of shading correction has not been evaluated, the read sensitivity due to deterioration of the photoelectric conversion parts such as the light source and image sensor due to the deterioration of the optical system due to paper dust, dust, etc. It is not known that the deterioration of the shading correction accuracy is deteriorated and the shading correction accuracy is deteriorated. Even in such a case, there is a problem that the same image processing is performed and the image quality is deteriorated.

Therefore, in the conventional ones described in the above-mentioned respective publications, how to make the shading coefficient low noise, the life of the light source or the white reference plate is determined from the white reference data read from the white reference plate. It was intended to properly perform the shading correction depending on whether or not to determine the effect of partial reflectance when reading the white reference plate. As a result, the deterioration of the reading system due to the contamination of the optical system and the change over time cannot be properly determined, and there is a problem that the image quality is deteriorated.

In particular, when a document is read at the time of transmission by a facsimile apparatus, the image quality of the read result cannot be recognized by the operator on the transmission side, maintenance is not properly performed, and the image quality deteriorates. It will result in continued use.

Therefore, the invention according to claim 1 prevents the deterioration of the optical system and the deterioration of the quality due to dust and scratches by judging the correction accuracy of the shading correction before scanning the original. It is an object of the present invention to provide an image reading device capable of improving image quality.

According to the second aspect of the present invention, the shading correction accuracy is determined based on the binarized image data, and the image processing step of the ordinary image reading apparatus is used to
It is an object of the present invention to provide an image reading apparatus capable of determining shading correction accuracy.

According to a third aspect of the present invention, the shading correction accuracy is determined based on the binarized image data obtained by binarizing the image data of the white reference member by changing the binarization threshold value a predetermined number of times. It is an object of the present invention to provide an image reading device capable of making a more precise determination of shading correction accuracy.

It is an object of the present invention to provide an image reading apparatus capable of determining the shading correction accuracy by increasing the binarization threshold value from a low value.

It is an object of the present invention to provide an image reading apparatus capable of determining the shading correction accuracy by lowering the binarization threshold value from a high value.

According to a sixth aspect of the present invention, there is provided an image reading apparatus capable of determining the shading correction accuracy based on the appearance of black image data when binarized by changing the binarization threshold value. It is an object.

According to the seventh aspect of the present invention, the shading correction determination process is performed a plurality of times, and when the predetermined accuracy cannot be obtained as a result, a warning is output.
While avoiding the effects of transient disturbances such as noise, the shading correction accuracy is determined, and it is recognized that there is an abnormality in the optical system, and the abnormality of the optical system is managed more appropriately and repaired. An object is to provide an image reading device that can be prompted.

It is an object of the present invention to provide an image reading apparatus capable of monitoring the shading correction accuracy according to the original reading mode.

According to the ninth aspect of the present invention, the image quality when the document is scanned can be predicted and determined in advance based on the result of binarizing the image data that is scanned by the white reference member and subjected to shading correction. An object is to provide an image reading device.

According to a tenth aspect of the present invention, there is provided an image reading apparatus capable of judging the image quality based on the appearance of black image data when binarized by changing the binarization threshold. It is an object.

According to the eleventh aspect of the present invention, the image quality judgment processing is performed a plurality of times, and if a predetermined accuracy cannot be obtained as a result, a warning is output, so that a transient noise or the like is output. While avoiding the influence of disturbance, while judging the image quality, letting you recognize that there is an abnormality in the optical system,
It is an object of the present invention to provide an image reading device capable of improving image quality.

According to a twelfth aspect of the present invention, there is provided an image reading apparatus capable of determining whether the optical system is deteriorated or is caused by scratches, dust or the like when the optical system is abnormal. The purpose is to do.

It is an object of the present invention to provide an image reading apparatus capable of judging the image quality according to the original reading mode.

It is an object of the present invention to provide an image reading apparatus capable of preventing / reducing the occurrence of black stripes, background stains, etc. in an image obtained by actually binarizing a document. There is.

It is an object of the present invention to provide an image reading apparatus capable of preventing / reducing the occurrence of background stains on an image obtained by actually performing halftone processing on a document.

It is an object of the present invention to provide an image reading apparatus capable of high-speed processing by hardware for determining the presence / absence of black image data and the rate of occurrence.

It is an object of the present invention to provide an image reading apparatus which can process the determination processing of the presence / absence of the black image data and the generation rate thereof with software at low cost.

It is an object of the present invention to provide an image reading apparatus capable of performing image processing according to the image quality judgment result.

The invention as set forth in claim 19 is characterized in that:
An object of the present invention is to provide an image reading apparatus that performs a shading correction accuracy or image quality determination process.

[0033]

According to another aspect of the present invention, there is provided an image reading apparatus including: a scanning unit that scans a white reference member and an original using an optical system; and a scanning unit that scans the white reference member. White reference data storage means for storing the obtained white reference data for each pixel, and shading correction means for performing shading correction on the image data obtained by scanning by the scanning means based on the white reference data for shading distortion by the optical system. And an image processing device that performs various image processes on the image data shading-corrected by the shading correction device, in the image reading apparatus, the scanning device scans the white reference member to obtain the white reference data. After storing in the white reference data storage means,
Before the scanning unit scans the document, the white reference member is again scanned, and the image data obtained by scanning the white reference member is shaded by the shading correction unit based on the white reference data. The above-described object is achieved by including control means for performing correction and determination means for determining the shading correction accuracy based on the image data of the white reference member that has been subjected to shading correction by the shading correction means.

Here, the scanning means scans the original using an optical system such as a light source, a mirror, a lens, and a photoelectric conversion means, converts the image of the original into an electric signal, and at the same time scans the original. Scan the white reference member.

The white reference data storage means stores the image data when the white reference member is scanned for one line for each pixel,
This white reference data is used as a reference for shading correction by the shading correction means and as a reference for image processing by the image processing means.

The shading correction means performs shading correction on the image data read by the scanning means in order to correct the shading distortion due to the optical system.

The image processing means binarizes the image data shading-corrected by the shading correction means,
Various image processing such as encoding processing or halftone processing is performed.

In order to collect white reference data for shading correction before scanning the document, the control means first causes the scanning means to scan the white reference member and stores the collected white reference data as white reference data. The white reference member is scanned again, and the image data of the white reference member is shading-corrected by the shading correction unit.

The determining means determines the shading correction accuracy based on the image data obtained by performing the shading correction on the image data of the white reference member.

According to the above arrangement, before scanning the document,
You can judge the correction accuracy of shading correction,
It is possible to prevent deterioration of quality due to deterioration of the optical system, dust, scratches, etc., and improve image quality.

According to a second aspect of the present invention, scanning means for scanning the white reference member and the original by using the optical system, and white reference data for each pixel obtained by the scanning means scanning the white reference member are stored. White reference data storage means, shading correction means for performing shading correction of shading distortion due to the optical system on image data obtained by scanning by the scanning means based on the white reference data, and shading correction performed by the shading correction means. In the image reading apparatus including image processing means for performing various image processing on the image data, the white reference data is stored in the white reference data storage means by scanning the white reference member by the scanning means. After that, the scanning means again scans the white reference member and scans the white reference member before scanning the document. The obtained image data is subjected to shading correction by the shading correction means based on the white reference data, and then the image processing means is binarized with a predetermined binarization threshold value, and the shading correction means is used for shading. Determination means for determining the shading correction accuracy based on the binarized image data obtained by binarizing the corrected image data of the white reference member with a predetermined binarization threshold value. By doing so, the above object is achieved.

According to the above configuration, the shading correction accuracy can be determined based on the binarized image data, and the shading correction accuracy can be determined by using the image processing process of the normal image reading apparatus. You can As a result, the shading correction accuracy determination process can be made simple and easy.

In this case, for example, as described in claim 3, the image processing means sequentially changes the binarization threshold value of the image data of the white reference member which is shading-corrected by the shading correction means. 2 times
The binarization may be performed by the image processing unit, and the shading correction accuracy may be determined based on the binarized image data binarized by the image processing unit by changing the binarization threshold.

According to the above arrangement, the shading-corrected image data of the white reference member is binarized based on the binarized image data obtained by binarizing the image data for a predetermined number of times by changing the binarization threshold value. The accuracy can be determined, and more precise shading correction accuracy can be determined.

Further, for example, as described in claim 4, the image processing means performs the binarization by sequentially increasing the binarization threshold value from a predetermined low value at predetermined intervals, and the determination means. Is a determination of the shading correction accuracy based on the binarization threshold when black image data first appears in the binarized image data binarized by the image processing unit by sequentially increasing the binarization threshold. May be performed.

According to the above configuration, the appearance of black image data in the binarized image data when the binarization threshold is increased from a low value is monitored and the binarization threshold at that time is set. The shading correction accuracy can be determined based on this, and the shading correction accuracy can be determined more accurately and easily.

Further, for example, as described in claim 5, the image processing means performs the binarization by sequentially lowering the binarization threshold value from a predetermined high value at predetermined intervals, and the determination means. Is for determining the shading correction accuracy based on the binarization threshold value when the binarized image data binarized by the image processing means sequentially lowering the binarization threshold value is all white image data for the first time. May be performed.

According to the above configuration, the binarized image data when the binarized threshold is lowered from a high value is monitored, and based on the binarized threshold when all the white image data is obtained. The shading correction accuracy can be determined, and when the deterioration of the optical system is small, the shading correction accuracy can be determined more quickly and with high accuracy.

Further, for example, as described in claim 6, the image processing means sequentially lowers the binarization threshold value from a predetermined high value at predetermined intervals or sequentially from a predetermined low value. The binarization is performed by raising the binarization at a predetermined interval, and the determining unit causes the image processing unit to sequentially lower or raise the binarization threshold to binarize the black image data. The shading correction accuracy may be determined based on the above.

According to the above configuration, the shading correction accuracy is determined based on the appearance of the black image data when the binarization threshold is changed and binarized, for example, the increase rate and the decrease rate of the black image data. Therefore, the shading correction accuracy can be determined more accurately and easily.

Further, for example, as described in claim 7, when the shading correction accuracy judged by the judging means is equal to or less than a predetermined reference correction accuracy, the control means sets the white reference data by the scanning means. To perform the shading correction determination process from the scan for collecting
If the shading correction accuracy of the judgment result obtained by performing the shading correction judgment process a predetermined number of times is less than or equal to the reference correction accuracy, a warning indicating that the optical system has an abnormality may be output.

Here, as the reference correction accuracy, for example,
The minimum correction accuracy is set to the limit at which the influence of noise and the like when scanning a document is allowed.

According to the above configuration, the shading correction determination process is performed a plurality of times, and the shading determination can be performed while avoiding the influence of transient disturbance such as noise, and the noise and the like can be reduced. Regardless, if the reference correction accuracy cannot be obtained, a warning can be output and it can be recognized that there is an abnormality in the optical system. As a result, the abnormality of the optical system can be managed more appropriately, the restoration can be promoted, and the image quality can be improved.

Further, for example, as described in claim 8, the determining means changes the reference correction accuracy in accordance with an original reading mode such as a halftone reading mode or a simple binary reading mode. May be.

According to the above configuration, it is possible to monitor the shading correction accuracy according to the document reading mode, and it is possible to appropriately manage the optical system while improving the image quality at the time of reading the document.

According to the image reading apparatus of the present invention, the scanning means for scanning the white reference member and the original by using the optical system, and the white for each pixel obtained by the scanning means scanning the white reference member. White reference data storage means for storing reference data, shading correction means for shading correction of shading distortion due to the optical system in image data obtained by scanning by the scanning means based on the white reference data, and the shading correction means. In the image reading apparatus including an image processing unit that performs various image processes on the image data that is shading-corrected by, the white reference data is stored in the white reference data storage unit by causing the scanning unit to scan the white reference member. , The white reference member is again scanned a predetermined number of times before being scanned by the scanning means. After the image data obtained by scanning the white reference member is subjected to shading correction by the shading correction means, the image processing means is provided with a binarization threshold value each time the scanning means scans the white reference member. A control unit that sequentially raises a predetermined high value at a predetermined interval, or sequentially lowers a predetermined low value at a predetermined interval to perform binarization, and the image processing unit sequentially increases the binarization threshold value. Based on the binarization threshold when the lowered and binarized image data becomes all white image data for the first time, or the binarization threshold when the black image data appears for the first time, the scanning unit is configured to The above-described object is achieved by including a determination unit that determines the image quality when scanning the document.

According to the above configuration, based on the result of binarizing the image data obtained by scanning the white reference member and performing shading correction, the image quality when the document is scanned is predicted in advance before scanning the document. It is possible to make a determination and improve the image quality.

In this case, for example, according to a tenth aspect, the judging means selects the binarized image data binarized by the image processing means by raising or lowering the binarizing threshold value. Based on the appearance of black image data of
The image quality may be determined.

According to the above configuration, the image quality is determined based on the appearance of black image data when binarizing by changing the binarization threshold, for example, the increase rate or the decrease rate of the black image data. Therefore, the image quality can be determined more accurately and easily.

Further, for example, when the binarization threshold value is equal to or less than a predetermined reference threshold value, the control means scans the white reference data for scanning by the scanning means. From the image quality determination process,
If the determination results obtained by performing the image quality determination processing a predetermined number of times are all less than or equal to the reference threshold value, a warning indicating that the optical system has an abnormality may be output.

According to the above configuration, the image quality determination process can be performed a plurality of times, and the image quality determination process can be performed while avoiding the influence of transient disturbance such as noise.
When the appropriate image quality cannot be obtained despite the reduction of noise and the like, a warning can be output and it can be recognized that there is an abnormality in the optical system. As a result, the abnormality of the optical system can be managed more appropriately, restoration can be promoted, and image quality can be improved.

Further, for example, as described in claim 12, the image reading device stores a black pixel appearance that stores an appearance position of the black image data when the binarization threshold value is raised or lowered. The determination means further includes position storage means, and the determination means is configured such that when the appearance position of the black image data stored in the black pixel appearance position storage means is continuous in a predetermined local area, scratches, dust, and the like are generated in the optical system. It may be determined that there is an abnormality.

According to the above construction, when there is an abnormality in the optical system, it can be classified and judged whether it is due to deterioration of the optical system or due to scratches or dust.
The abnormality of the optical system can be determined more appropriately. As a result, the optical system can be repaired more appropriately.

Further, for example, as described in claim 13, the judging means sets the judgment criterion for judging the image quality as a reading mode of a document such as a halftone reading mode or a simple binary reading mode. It may be changed according to.

According to the above arrangement, the image quality can be determined according to the original reading mode, and the image quality can be determined more appropriately.

Further, for example, as described in claim 14, when the control means binarizes the image data obtained by scanning the original document by the image processing means based on the determination result of the determination means. The binarization threshold may be changed.

According to the above arrangement, the binarization threshold value for binarizing the image data obtained by actually scanning the original can be changed according to the image quality judgment result, that is, the shading correction accuracy. It is possible to prevent / reduce the occurrence of black streaks and background stains in the binarized image and improve the image quality.

Further, for example, as described in claim 15, the image processing means performs gradation processing of the image data obtained by reading the original document to a predetermined gradation, and the control means controls the image of the determination means. The number of gradations during the gradation processing by the image processing means may be changed based on the quality determination result.

According to the above arrangement, the number of gradations in gradation processing of the image data obtained by actually scanning the original can be changed according to the result of the image quality judgment, that is, the shading correction accuracy. It is possible to prevent / reduce the occurrence of background stains on an image and improve the image quality.

Further, for example, as described in claim 16, the judging means is a judging circuit for judging whether or not the image data of the binarized white reference member is black image data. A counter for counting the black image data discriminated by the discriminating circuit may be provided, and the determination processing of the presence or absence of the black image data or the generation ratio may be processed by hardware.

According to the above configuration, it is possible to perform the determination process of the presence / absence of the black image data, the generation ratio, etc. at high speed while reducing the load on the software, thereby increasing the processing speed of the image reading apparatus. Can be improved.

Further, for example, as described in claim 17, the judging means includes whether the black pixel is included in the binarized image data of the white reference member, or the black image data The generation rate determination process may be performed by software.

According to the above construction, it is not necessary to add a circuit to determine the presence / absence of the black image data, the generation ratio, etc., and the image reading apparatus can be made inexpensive.

The image reading apparatus according to the eighteenth aspect of the present invention is
Scanning means for scanning the white reference member and the original using an optical system; white reference data storage means for storing white reference data in pixel units obtained by the scanning means scanning the white reference member; and the white reference. Based on various processing parameters, shading correction means for shading-correcting shading distortion by the optical system in the image data obtained by the scanning means based on the data, and various processing parameters for the image data shading-corrected by the shading correction means. In an image reading apparatus including image processing means for performing various image processing, the scanning means scans the white reference member to store the white reference data in the white reference data storage means, and then the scanning. An image obtained by scanning the white reference member and scanning the white reference member before the means scans the document. The document based on the correction result when the shading correction is performed by the shading correction unit based on the white reference data, and the shading correction is performed on the image data of the white reference member by the shading correction unit. A determination unit that determines the image quality when scanning, and the image processing when the control unit performs image processing on the image data obtained by scanning the document based on the determination result of the determination unit. The above object is achieved by varying the processing parameters of the means.

According to the above arrangement, the result of the image quality judgment,
That is, the image processing can be performed according to the shading correction accuracy, and even when the shading correction accuracy is lowered, the appropriate image processing can be performed to improve the image quality.

In each of the above cases, for example, claim 19
As described in [1], the control means may execute the shading correction accuracy determination processing or the image quality determination processing at predetermined time intervals.

With the above arrangement, it is possible to manage the shading correction accuracy or the image quality while improving the processing speed of the image reading apparatus.

[0078]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

Since the embodiment described below is a preferred embodiment of the present invention, various technically preferable limitations are attached, but the scope of the present invention is particularly limited in the following description. Unless specifically stated to limit the present invention, the present invention is not limited to these embodiments.

FIGS. 1 to 3 are views showing a first embodiment of an image reading apparatus of the present invention, and this embodiment is applied to a facsimile apparatus.

In FIG. 1, the facsimile machine 20 is
System control unit 21, system memory 22, parameter memory 23, scanner 24, plotter 25, network control unit 2
6, modem 27, image memory 28, encoding / decoding unit 2
9 and an operation panel 30 and the like, and each of the above parts is connected to a bus 31.

System control section (control means, determination means) 2
1 is a CPU (Central Processing Unit), a ROM (R
(ead Only Memory), etc., and stores various programs such as a basic processing program as the facsimile device 20, a shading correction accuracy determination processing program, and an image quality determination station program in the ROM, and executes the above-described processing. It stores the system data required for. In the system control unit 21, the CPU uses the system memory 22 as a work memory to control each unit of the facsimile device 20 based on the program in the ROM to execute the basic processing as the facsimile device 20. The shading correction accuracy determination process and the image quality determination process are performed.

The parameter memory 23 stores various parameter information necessary for facsimile communication.

As shown in FIG. 2, the scanner 24 is attached to the guide member 42 for guiding the original 41 conveyed by the conveying roller (not shown), and is attached to the guide member 42 to guide the original 41 and dust to the optical system. A target glass 43 for preventing dust and the like from being mixed, a white reference plate 44 for correcting shading distortion caused by an optical system, a light source 45 for irradiating the conveyed document 41 and the white reference plate 44 with light,
The shading correction circuit 52 includes a mirror 47, a lens 46, an image sensor 48, an amplifier 49, an A / D converter 50, a peak hold circuit 51, a shading correction circuit 52, a line buffer 53 and a digital image processing circuit 54. And digital image processing circuit 54
Are connected to the system control unit 21 via a bus 31.

When scanning the white reference plate (white reference member) 44, the light from the light source 45 passes through the target glass 43, is irradiated to the white reference plate 44, and is reflected by the white reference plate 44. The light is imaged on the image sensor 48 via the mirror 46 and the lens 47 at a predetermined reduction ratio. Further, when scanning the document 41, the light from the light source 45 is applied to the document 41 conveyed on the target glass 43 through the target glass 43, and the light reflected by the document 41 is reflected by the mirror 47 and the lens 46. An image is formed on the image sensor 48 at a predetermined reduction ratio via the.

The image sensor 48 converts the imaged optical information into an electric signal and outputs the electric signal to the amplifier 48.
Is an operational amplifier (op amp),
The analog image signal input from the image sensor 48 is amplified by a predetermined magnification and output to the A / D converter 50 and the peak hold circuit 51.

Therefore, the light source 45, the mirror 46,
The lens 47 and the image sensor 48 function as a scanning unit as a whole.

The peak hold circuit 51 is the maximum value (peak value) of the image signal for one line input from the amplifier 48.
Is detected and held.

A / D (Analog to Digita) converter 50
Quantizes the image signal input from the amplifier 49 based on the peak value held by the peak hold circuit 51,
Output to the shading correction circuit 52.

Line buffer (white reference data storage means)
53 is an A / D converter 5 when the white reference plate 44 is scanned
Image data for one line output by 0 is stored as white reference data, and is referred to in the shading correction by the shading correction circuit 52 and the image processing in the digital image processing circuit 54.

The shading correction circuit (shading correction means) 52 is controlled by the A
The shading distortion caused by the characteristics of the optical system is added to the image data input from the D / D converter 50.
The digital image processing circuit 54 performs shading correction processing for correcting while referring to the image data stored in FIG.
Output to

Digital image processing circuit (image processing means)
The reference numeral 54 operates under the control of the system control unit 21 to refer to the image data stored in the line buffer 53, or to utilize the line buffer 53 to convert the image data input from the shading correction circuit 52 into two. In addition to binarization and halftone processing, various image processing is performed.
Store in the line buffer 22a.

The line buffer 22a is for temporarily storing the image data binarized or halftone processed by the digital image processing circuit 54, and a part of the system memory 22 shown in FIG. 1 is used. .

Therefore, the scanner 24 uses the white reference plate 4 to obtain the white reference data for shading correction.
4 is scanned, the image signal converted by the image sensor 48 into an electric signal is amplified by the amplifier 49, and the peak value held by the peak hold circuit 51 is used as a reference.
After being digitally converted by the / D converter 50, it is stored as white reference data in the line buffer 53 via the shading correction circuit 52. Then, as will be described later, in order to determine the shading correction accuracy, the white reference plate 4 is again used.
4 is similarly converted into an electric signal by the image sensor 48, converted into a digital signal by the A / D converter 50, and the line buffer 53 by the shading correction circuit 52.
After shading correction based on the white reference data of
It is binarized by the digital image processing circuit 54 and temporarily stored in the line buffer 22a. This line buffer 22a
The system control unit 21 determines the shading correction accuracy based on the binarized image data.

After that, when scanning the original 41, the image signal converted into an electric signal by the image sensor 48 is amplified by the amplifier 49, converted into a digital signal by the A / D converter 50, and then the white reference of the line buffer 53. With reference to the data, the shading correction circuit 52 performs shading correction, the digital image processing circuit 54 performs various image processing, and then the data is transferred to the line buffer 22a.

The shading correction accuracy determination process using the scanner 24 will be described in detail later.

Although not shown, the scanner 24 is usually equipped with an ADF (automatic document feeder).
Feeds the set plurality of originals 41 one by one to the target glass 43, that is, the reading unit.

Referring again to FIG. 1, as the plotter 25, for example, a thermal recording device using a thermal element, an electrophotographic recording device, or the like is used.
When the thermal recording device is used, an image is recorded directly on the thermal recording paper or indirectly on the normal recording paper via an ink sheet.

The network control unit 26 is connected to the modem 27, and a line (for example, a telephone line) is connected to the network control unit 26. The network control unit 26 is the system control unit 21.
It operates under the control of, automatically receives a call from a line, performs automatic call processing to the line, and exchanges a facsimile control signal with a partner facsimile machine, The facsimile communication procedure is executed by setting communication functions and exchanging various control information.

The modem 27 operates under the control of the system controller 21 to modulate the transmission signal and demodulate the reception signal.

The image memory 28 is, for example, a large capacity RA.
It is composed of an M (Random Access Memory) or a hard disk device, and mainly stores image data. That is, image data for transmission read by the scanner 24 and received image data are accumulated in the image memory 28, and are read out at a predetermined time under the control of the system control unit 21 to perform transmission processing, recording processing, or the like. Be used for.

The encoding / decoding unit 29 shortens the transmission time of image data and increases the efficiency of storage in the image memory 28, and compresses (encodes) image data during transmission.
In addition, the encoded image data is reproduced (decoded) into the original image data at the time of reception.

The operation panel 30 is provided with various operation keys such as a numeric keypad, a start key, a stop key, and a function key, and a display (for example, a liquid crystal display), and various operation commands such as a transmission operation are provided from the operation keys. Is entered. In addition, the display of the operation panel 30 displays the content of the command input from the operation keys and various kinds of information notified from the facsimile apparatus 1 to the operator, and the shading correction accuracy and the determination result of the image quality and the abnormality notification described later. Etc. are displayed and output.

Next, the operation will be described.

In the present embodiment, after the white reference plate 44 is scanned to acquire the white reference data, the white reference plate 44 is again scanned a preset number of times before the original 41 is read to perform shading correction. The feature lies in the determination of accuracy and image quality.

The shading correction accuracy processing and the image quality determination processing will be described below with reference to the flowchart of FIG.

When an instruction to read the original 41 is input from the operation panel 30, the system control unit 21 causes the various parameters necessary for reading the original 41 and various parameters necessary for the shading correction accuracy determination process, particularly the shading correction accuracy. The count value of the counter N that counts the number of times of scanning the white reference plate 44 (the number of times of white reference data collection) for determination is initialized (N = 0) (step S
1), the upper limit TH of the number of white reference data collections is set (step S2). This white reference data collection frequency upper limit TH is
An initial value is set in advance in the ROM in the system control unit 21, and this initial value is set as the upper limit TH in step S2, but it can be changed and set by inputting the upper limit TH from the operation panel 30. You can also

Next, the system control section 21 controls the original reading mode designated by the operation panel 30, that is, the simple binary reading mode or the original reading mode such as the halftone reading mode for reading a photograph or the like. Is determined (step S3), and the correction accuracy determination level LV corresponding to the determined document reading mode, that is, the correction accuracy determination level of shading correction is set (step S4).

The correction accuracy determination level LVH is stored in advance in the ROM or the like for each reading mode, and in each reading mode, the minimum level of shading correction accuracy that does not affect the image quality is set.

For example, when the original reading mode is the halftone reading mode, the system control unit 21 requires a high correction as the correction accuracy. Therefore, a high value is set as the correction accuracy determination level LV, and the simple 2 In the value reading mode, it is set to a low value that can guarantee a binary image.

After that, the system controller 21 controls the light source 45
Is turned on (LAMP ON) (step S5), first,
In order to acquire the white reference data, the white reference plate 44 is scanned, and the image data digitally converted by the A / D converter 50 is stored (collected) in the line buffer 53 as white reference data by the above-described procedure ( Step S6).

Next, the system control unit 21 scans the white reference plate 44 again (step S7), and the white reference plate 4 is scanned.
The shading correction accuracy is calculated based on the image data when scanning 4 (step S8), and it is checked whether the shading correction accuracy exceeds the correction accuracy determination level LV set in step S4 (step S9).

That is, when the image signal obtained by scanning the white reference plate 44 again is digitally converted by the A / D converter 50, the system controller 21 causes the shading correction circuit 52 to store the white signal stored in the line buffer 53. Shading correction is performed based on the reference data, and the shading-corrected image data is binarized by a predetermined threshold value (threshold level) by the digital image processing circuit 54 and transferred to the line buffer 22a. The system control unit 21 calculates the correction accuracy depending on how many black pixels are included in the binarized image data, and whether the correction accuracy exceeds the correction accuracy determination level LV set in step S4. Is determined in step S9.
The method of calculating the shading correction accuracy is not limited to the above method.

When the calculated correction accuracy does not exceed the correction accuracy determination level LV in step S9, the system control unit 21 increments the counter N for counting the number of white reference data collections (step S1).
0), the incremented counter N indicates the upper limit TH of the number of white reference data collection times set in step S2.
Is checked, that is, whether white reference data has been collected up to the preset upper limit TH of white reference data collection times (step S11).

In step S11, when the count number of the counter N does not exceed the upper limit TH of the number of white reference data collections, the system control unit 21 collects the white reference data up to a preset number of white reference data collections. If not, the process returns to step S6, the same processing as above is performed from the collection of the white reference data, and when the white reference data is collected, the white reference plate 44 is scanned again (step S7) to obtain the shading correction accuracy. Is calculated (step S8).

When the calculated correction accuracy does not reach the correction accuracy determination level LV as described above, the system control unit 21 increments the counter N (step S10) in the same manner as described above (step S10). It is checked whether or not the count value of exceeds the upper limit TH of the number of white reference data collections (step S11).

By performing the above processing by collecting the white reference data and performing the shading correction processing a predetermined number of times, the influence of noise or the like can be excluded. However, despite the influence of noise or the like being excluded, in step S11, When the value exceeds the upper limit TH, the system control unit 21 determines that the light source 45, the white reference plate 44, or the optical system such as the mirror 46, the lens 47, and the image sensor 48 is deteriorated or soiled, and the shading correction accuracy is appropriate. Is output to the display of the operation panel 30, and when necessary, a warning sound is generated and a warning is given to end the shading correction accuracy determination processing ( Step S12).

In step S9, when the calculated correction accuracy exceeds the correction accuracy determination level LV, the system control unit 21 determines that the appropriate shading correction accuracy is obtained, and the normal reading process of the original document 41 is performed. Then, the shading correction determination process ends (step S13).

As described above, in the present embodiment, after the white reference data is collected, the white reference plate 44 is read again to perform the shading correction, and the shading correction accuracy at that time is calculated. It is determined whether the calculated shading correction accuracy exceeds the correction accuracy determination level LV set corresponding to the original reading mode. When the shading correction accuracy does not exceed the correction accuracy determination level LV, white reference data is collected again. Shading correction of the image data read from the white reference plate 44 is performed,
It is judged whether the shading correction accuracy exceeds the correction accuracy judgment level LV. If the shading correction accuracy does not exceed the correction accuracy determination level LV even after the above processing is performed a predetermined number of times, it is possible to determine that the optical system is deteriorated or dirty, and issue a warning. Deterioration and dirt of the optical system can be discriminated in advance based on the accuracy, and the operator can be prompted to perform appropriate processing. As a result, it is possible to prevent the image of the document 41 whose image quality is deteriorated from being transmitted before the operator notices it, and it is possible to improve the image quality.

FIG. 4 to FIG. 7 are views showing a second embodiment of the image reading apparatus of the present invention. In this embodiment, image data obtained by scanning the white reference plate after collecting the white reference data. The threshold for binarizing is sequentially increased to determine the correction accuracy.

This embodiment is applied to an embodiment similar to the above-described first embodiment, and in the description of this embodiment, the reference numerals used in the first embodiment are used as they are. It will be described below by using.

In the present embodiment, as shown in FIG. 4, the system control unit 21 performs various initial settings when a reading instruction is given from the operation panel 30, and particularly,
Counters N and 1 for counting the number of white reference data collections
The count value of the pixel counter I that counts the pixels in the line is initialized (N = 0, I = 0) (step P1),
The upper limit TH of the number of white reference data collections is set (step P2). In the present embodiment, the following description will be given assuming that the number of pixels for one line is 2048 pixels.

Next, the system control unit 21 sets the initial binarization threshold UPTH and the step width (increasing step) α for raising the threshold (step P3), and the operation panel 30.
The original reading mode specified by is judged (step P
4) The correction accuracy determination level LV corresponding to the determined original reading mode is set (step P5).

After that, the system controller 21 controls the light source 45
Is turned on (step P6), first, in order to acquire the white reference data, the white reference plate 44 is scanned, and the image data digitally converted by the A / D converter 50 is used as the white reference data by the above procedure. The data is stored in the line buffer 53 (step P7).

Next, as shown in FIG. 5, the system control unit 21 sets the initial binarization threshold UPTH set in step P3 as the temporary binarization threshold Th (step P
8) Then, the white reference plate 44 is again scanned, and the image data when the white reference plate 44 is scanned is converted into the multivalued image data VI.
It is stored in the line buffer 22a as D (I) (step P9).

When the white reference plate 44 is rescanned to determine the correction accuracy, the system controller 21 sets the pixel counter I to 1
By incrementing only, and the multi-valued image data VID (I) of the pixel indicated by the pixel counter I is calculated in step P8.
Is smaller than the binarization threshold Th set in step 1, that is,
The multi-valued image data VID (I) of the pixel is the binarization threshold T
It is checked whether the image data is smaller than h and is black image data (step P11), and the multi-valued image data VID of the pixel is checked.
When (I) exceeds the binarization threshold Th, it is determined that the pixel is white image data, and it is checked whether or not the pixel counter I has counted one line (2048 pixels) (step P12).

In step P12, when the pixel counter I has not counted for one line, the process returns to step P10, the pixel counter I is incremented in the same manner as above, and the next pixel is also counted in the same manner. It is checked whether the value image data VID (I) is smaller than the binarization threshold Th.

If the multi-valued image data VID (I) of all the pixels on one line is white image data by performing the above-described processing sequentially (steps P11 and P12), the binarization threshold Th is increased by the increasing step α. After increasing the pixel counter I to "0" (step P13), step P
Returning to step 10, the multi-valued image data VID (I) stored in the line buffer 22a is compared with the binarization threshold Th that has been increased by the increasing step α in the same manner as above (step P11).

When all the multivalued image data VID (I) are white image data larger than the binarization threshold Th (step P12), the binarization threshold Th is increased again by performing the same processing as above. The pixel counter I is cleared (step P13) while the value is increased by step α, and the same processing as described above is performed (steps P10 to P13).

After performing the above processing, in step P11, the multi-valued image data VID smaller than the binarization threshold Th is obtained.
(I) That is, when black image data appears, the process proceeds to step P14, the shading correction accuracy at that time is calculated (step P14), and the calculated shading correction accuracy is the correction accuracy determination level set in step P5. Check if LV is exceeded (Step P
15).

In step P15, when the calculated shading correction accuracy does not exceed the correction accuracy determination level LV, the system control unit 21 increments the counter N that counts the number of white reference data collections (step P16). The incremented counter N is
It is checked whether the upper limit TH of the number of white reference data collections set in step P2 has been exceeded, that is, whether the white reference data has been collected up to the upper limit TH of the number of white reference data collections set in advance (step P17).

In step P17, when the count number of the counter N does not exceed the upper limit TH of the number of white reference data collections, the system control unit 21 collects the white reference data up to the preset number of white reference data collections. If it is determined that the white reference data is not obtained, the process returns to step P7 in FIG. 5 to perform the same processing from the white reference data collection, and the white reference data is collected again, as shown in FIG.
Is set as the binarization threshold Th (step P
8), scan the white reference plate 44 again (step P9),
Similarly to the above, 2 for each multi-valued image data VID (I)
It is checked whether it is smaller than the threshold value Th, that is, whether black image data is included (step P11).

The above processing is performed for the multivalued image data V for one line.
If the black image data is not included in one line for the ID (I) (steps P10 to P1).
2) The system control unit 21 raises the binarization threshold Th by raising the binarization threshold Th by the step α (step P1).
3) Similarly to the above, it is checked whether the multi-valued image data VID (I) includes black image data (steps P10 to P).
12) When black image data appears in step P11, correction accuracy is calculated (step P14), and it is checked whether the calculated correction accuracy is higher than the correction accuracy determination level LV (step P15).

In step P15, when the calculated correction accuracy is lower than the correction accuracy determination level LV, the system control unit 21 increments the counter N in the same manner as described above to obtain the upper limit TH of the number of times of white reference data collection. Is checked (step P17), and if not exceeded, the process returns to step P7 and the same processing as described above is performed (steps P7 to P17).

Even though the white reference data was redone and shading correction processing was performed to eliminate the influence of noise and the like, the binarization threshold Th was gradually increased to check the shading correction accuracy. In step P15, when the correction accuracy determination level LV cannot be obtained and the upper limit TH of the number of white reference data collection times is exceeded, the system control unit 21 causes the light source 45, the white reference plate 44, the mirror 46, or the lens. It is judged that the appropriate shading correction accuracy cannot be obtained due to deterioration or dirt of the optical system such as 47 and the image sensor 48, and that fact is displayed and output on the display of the operation panel 30, and when necessary. , A warning sound is generated, a warning is given, and the shading correction accuracy determination processing ends (step P1). ).

In step P15, when the calculated correction accuracy exceeds the correction accuracy determination level LV, the system control unit 21 determines that the appropriate shading correction accuracy is obtained, and the normal reading process of the original 41 is performed. Then, the shading correction determination process ends (step P19).

As described above, in the present embodiment, after the white reference data is sampled, the white reference plate 44 is read again, and each shading correction is performed as shown in FIGS. 6 and 7. For each multi-valued image data VID (I), the initial binarization threshold UPTH is compared with a set binarization threshold Th to determine whether the image data is white image data or black image data, and the multi-valued image data for all one line. If VID (I) is white image data, the binarization threshold Th is increased by the increasing step α, and
It is checked whether black image data is included in the multi-valued image data VID (I) of the line. All multi-valued image data VI
If D (I) is white image data, the binarization threshold Th is increased again by the increasing step α and the same check is performed.

In this case, when the shading correction accuracy is high, the multivalued image data V read from the white reference plate 44 is read.
Since the black image data should not be included in ID (I), as shown in FIG. 6, black image data is not detected up to the upper limit of the initial binarization threshold UPTH + 8α as the binarization threshold Th, for example. However, when the shading correction accuracy is low, for example, as shown in FIG. 7, black image data appears at an initial binarization threshold UPTH + 4α.

The shading correction accuracy at the time when this black image data appears is calculated, and the correction accuracy determination level LV is calculated.
By comparing with, the shading correction accuracy is determined, and it is determined whether a warning is generated or the reading process of the document 41 is performed.

Therefore, the judgment of the shading correction accuracy can be made more appropriately and accurately.

FIGS. 8 to 11 are views showing a third embodiment of the image reading apparatus of the present invention. In this embodiment, image data obtained by scanning the white reference plate after collecting the white reference data is shown. The threshold value for binarizing is sequentially decreased to determine the correction accuracy.

This embodiment is applied to an embodiment similar to the above-described first embodiment, and in the description of this embodiment, the reference numerals used in the first embodiment are used as they are. It will be described below by using.

In the present embodiment, as shown in FIG. 8, the system control unit 21 makes various initial settings when a reading instruction is given from the operation panel 30, and particularly,
Counters N and 1 for counting the number of white reference data collections
The count value of the pixel counter I for counting the pixels in the line is initialized (N = 0, I = 0) (step Q1),
The upper limit TH of the number of white reference data collections is set (step Q2). Also in the present embodiment, the following description will be made assuming that the number of pixels for one line is 2048 pixels.

Next, the system control unit 21 sequentially lowers the binarization threshold value, and the highest initial binarization threshold value DWNT.
A step width (lowering step) α for lowering H and the binarization threshold value is set (step Q3), and the original reading mode designated by the operation panel 30 is determined (step Q4).
The correction accuracy determination level LV corresponding to the determined original reading mode is set (step Q5).

After that, the system controller 21 controls the light source 45
Is turned on (step Q6), first, in order to acquire the white reference data, the white reference plate 44 is scanned and the white reference data is stored in the line buffer 53 (step Q7).

Next, as shown in FIG. 9, the system control unit 21 sets the initial binarization threshold value DWNTH set in the above step Q3 as the temporary binarization threshold value Th (step Q8), and again sets the white binarization threshold value to white. The reference plate 44 is scanned, and the image data when the white reference plate 44 is scanned is converted into multi-valued image data V.
It is stored in the line buffer 22a as ID (I) (step Q9).

When the white reference plate 44 is re-scanned to determine the shading correction accuracy, the system control unit 21 increments the pixel counter I by 1 and multivalued image data VID of the pixel indicated by the pixel counter I. (I)
Is smaller than the binarization threshold Th set in step Q8, that is, the multi-valued image data VID (I) of the pixel.
Is smaller than the binarization threshold Th and is black image data (step Q11), and when the multi-valued image data VID (I) of the pixel exceeds the binarization threshold Th, the pixel is white. It is determined that the data is image data, and it is checked whether the pixel counter I has counted one line (2048 pixels) (step Q12).

In step Q12, when the pixel counter I is not counting for one line, the process returns to step Q10, the pixel counter I is incremented in the same manner as above, and the next pixel is also counted in the same manner. It is checked whether the value image data VID (I) is smaller than the binarization threshold Th (step Q11).

When the multi-valued image data VID (I) of all the pixels on one line is black image data by sequentially performing the above processing (steps Q11 and Q12), the binarization threshold Th is decreased by the lowering step α. After lowering (Th = Th−α) and clearing the pixel counter I to “0” (step Q1
3), returning to step P10, the line buffer 22a
Similarly, the multi-valued image data VID (I) stored in is compared with the binarization threshold Th that is sequentially lowered by the lowering step α (step Q11).

When black image data appears in the middle of the processing similar to the above (steps Q10 to Q12),
The binarization threshold Th is lowered by the lowering step α, the pixel counter I is cleared (step Q13), and the same processing as the above is performed (steps Q10 to Q1).
3).

When all the multi-valued image data VID (I) in one line are white image data by performing the above processing, the process proceeds to step Q14, and the shading correction accuracy at that time is calculated (step Q14). It is checked whether the calculated shading correction accuracy exceeds the correction accuracy determination level LV set in step Q5 (step Q15).

When the calculated shading correction accuracy does not exceed the correction accuracy determination level LV in step Q15, the system control unit 21 increments the counter N for counting the number of white reference data collections (step Q16). The incremented counter N is
It is checked whether the upper limit TH of the number of white reference data collections set in the above step Q2 is exceeded (step Q17).

In step Q17, when the count number of the counter N does not exceed the upper limit TH of the number of white reference data collections, the system control unit 21 collects the white reference data up to the preset number of white reference data collections. If not, the process returns to step Q7 in FIG. 8 and the same processing as above is performed from the collection of the white reference data. When the white reference data is collected, the initial binarization threshold value DWNT is again displayed as shown in FIG.
After setting H as the binarization threshold Th (step Q
8), scan the white reference plate 44 again (step Q9),
Similarly to the above, 2 for each multi-valued image data VID (I)
It is checked whether it is smaller than the threshold value Th, that is, whether black image data is included (step Q11).

The above processing is performed for the multi-valued image data V for one line.
If ID (I) is included and black image data is included in one line (steps Q10 to Q12),
The system control unit 21 lowers the binarization threshold Th by the step of lowering the binarization threshold Th (step Q13), and in the same manner as above, checks whether the multi-valued image data VID (I) includes black image data. (Steps Q10 to Q12),
When black image data does not appear in one line, correction accuracy is calculated (step Q14), and it is checked whether the calculated correction accuracy is higher than the correction accuracy determination level LV (step Q15).

In step Q15, when the calculated correction accuracy is lower than the correction accuracy determination level LV, the system control unit 21 increments the counter N in the same manner as described above to obtain the upper limit TH of the number of times of white reference data collection. Is checked (step Q17), and when not exceeded, the process returns to step Q7 and the same processing as described above is performed (steps Q7 to Q17).

Even though the white reference data was redone and shading correction processing was performed to eliminate the influence of noise and the like, the binarization threshold Th was gradually lowered to check the shading correction accuracy. In step Q15, when the correction accuracy determination level LV cannot be obtained and the upper limit TH of the number of white reference data collection times is exceeded, the system control unit 21 causes the light source 45, the white reference plate 44, the mirror 46, or the lens. It is judged that the appropriate shading correction accuracy cannot be obtained due to deterioration or dirt of the optical system such as 47 and the image sensor 48, and that fact is displayed and output on the display of the operation panel 30, and when necessary. , A warning sound is generated, a warning is given, and the shading correction accuracy determination processing ends (step Q1). ).

When the calculated correction accuracy exceeds the correction accuracy determination level LV in step Q15, the system control unit 21 determines that the appropriate shading correction accuracy is obtained, and the normal reading process of the original 41 is performed. Then, the shading correction determination process ends (step Q19).

As described above, in this embodiment, after the white reference data is sampled, the white reference plate 44 is read again, and each shading correction is performed as shown in FIGS. 10 and 11. For each multi-valued image data VID (I),
The initial binarization threshold value DWNTH is compared with the set binarization threshold value Th to determine whether it is white image data or black image data, and 1
If the multi-valued image data VID (I) in the line includes black image data, the binarization threshold value T is decreased by the descending step α.
By lowering h, it is checked whether the black image data is included in the multi-valued image data VID (I) of one line. When the black image data is included in the multi-valued image data VID (I) of one line, the binarization threshold Th is further lowered by the descending step α and the same check is performed.

In this case, when the shading correction accuracy is high, the multivalued image data V read from the white reference plate 44 is read.
Since the black image data should not be included in the ID (I), as shown in FIG. 10, for example, the black image data is reduced when the binarization threshold Th is lowered to the initial binarization threshold DWNTH-2α. Is not detected, but when the shading correction accuracy is low, for example, as shown in FIG.
Binarization threshold value T up to the initial binarization threshold value DWNTH-6α
Black image data cannot be detected until h is lowered.

The shading correction accuracy at the time when the black image data is no longer detected is calculated and compared with the correction accuracy determination level LV to determine the shading correction accuracy and issue a warning or read the original 41. It is decided whether to process.

Therefore, as compared with the case where the binarization threshold Th is increased more appropriately in the judgment of the shading correction accuracy, the judgment of the shading correction accuracy can be made more when the deterioration of the optical system has not progressed. Can be done promptly.

FIGS. 12 and 13 are views showing a fourth embodiment of the image reading apparatus of the present invention. In the present embodiment, a black line is blacked in one line of the image data obtained by scanning the white reference plate again. The hardware detects whether image data is included and how many black image data is included.

This embodiment is applied to the same facsimile machine as that of the first embodiment, and in the description of this embodiment, the reference numerals used in FIG. ,explain.

In FIG. 12, the facsimile device 1 according to the present embodiment has a black pixel detecting / counting circuit 60 incorporated in its scanner 24.
Includes an AND circuit 61, a counter 62, a host interface (HOST I / F) 63, and the like.

The AND circuit 61 stores in the binarized data B binarized by the digital image processing circuit 54 of FIG.
IDAT is input, and this binary data BIDAT is
The data is transferred to the system memory 22a via the host interface 63 and the bus 63.

A pixel synchronizing clock ELCK which is a pixel data transfer synchronizing clock is further input to the AND circuit (discriminating circuit) 61, and this pixel synchronizing clock ELC is inputted.
In synchronization with K, the binarized data BIDAT is transferred from the digital image processing circuit 54 to the AND circuit 61 and the host interface 63.

Then, this pixel synchronization clock ELCK
13 is a signal that becomes a high level “1” at the transfer timing of pixel data, and the binarized data BIDAT is “0” for white image data and black signal data. The data is “1”.

The AND circuit 61 uses the pixel synchronization clock EL.
Binary data BID transferred at CK timing
When the AT is black image data, that is, "1", the black signal which becomes "1" at the rising edge of the AT is counted by the counter 62.
Output to

The counter 62 counts the black signal of “1” input from the AND circuit 61 and outputs the count result to the system control unit 21 via the host interface 63.

The line synchronizing signal LNSYC shown in FIG. 13 is input to the reset terminal R of the counter 62, and the counter 62 receives the line synchronizing signal LNSY.
The count value is cleared by C.

Therefore, the black pixel detecting / counting circuit 60
Detects the presence or absence of black image data in one line, counts the black image data in one line, and outputs the detection result and the coefficient result to the system control unit 21.

That is, the black pixel detecting / counting circuit 60 is
As shown in FIG. 13, the binarized binarized data BID of the digital image processing circuit 54 transferred from the digital image processing circuit 54 in synchronization with the pixel synchronization clock ELCK.
If the AT has black image data, the AND circuit 61 detects the black image data, and the AND circuit 61 for one line from the input of the line synchronization signal LNSYC to the input of the next line synchronization signal LNSYC. The detected black image data is sequentially counted by the counter 62 and output to the system control unit 21 via the host interface 63.

Therefore, the system control unit 21 reads the white reference plate 44 again in order to collect the white reference data, and then reads the white reference plate 44 again in the same manner as in each of the above-described embodiments. After the shading correction is performed on the image data when the white reference plate 44 is read again based on the white reference data when the reference plate 44 is read, the digital image processing circuit 54 is binarized with a predetermined binarization threshold value. The binarized data BIDAT of this digital image processing circuit 54 is detected and counted by the black pixel detection / counting circuit 60, and the system control unit 21 determines the shading correction accuracy.

As a result, it is possible to quickly determine the shading correction accuracy while reducing the load on the system control unit 21.

14 to 15 are views showing an image reading apparatus according to a fifth embodiment of the present invention. This embodiment will be described below.
The image data obtained by scanning the white reference plate again is binarized while sequentially increasing the binarization threshold value, and 1 of the binarized image data is obtained.
The software detects whether there is black image data in the line.

This embodiment is applied to an embodiment similar to the above-mentioned first embodiment, and in the description of this embodiment, the reference numerals used in the above-mentioned first embodiment are used. The description will be given as it is.

In this embodiment, as shown in FIG. 14, when a reading instruction is issued from the operation panel 30, the system control unit 21 makes various initial settings, and particularly, the counter N and the pixel counter I. The count value is initialized (N = 0, I = 0) (step R1), the white reference data sampling frequency upper limit TH is set, and the initial binarization threshold UPTH is set.
And the rising step α is set (step R2). Also,
Also in this embodiment, the number of pixels for one line is 204
The following description will be given assuming that there are 8 pixels.

Next, the system controller 21 determines the original reading mode designated by the operation panel 30 and sets the correction accuracy determination level LV corresponding to the determined original reading mode (step R3), and the light source 45. Is turned on (step R4), the white reference plate 44 is scanned, and the image data obtained by scanning is stored in the line buffer 53 as white reference data (step R5).

Next, as shown in FIG. 15, the system control section 21 sets the temporary binarization threshold Th as the above step R2.
The initial binarization threshold UPTH set in step S6 is set (step R6), and the white reference plate 44 is scanned again (step R6).
7) The image data when the white reference plate 44 is scanned is subjected to shading correction by the shading correction circuit 52, and then binarized to be stored in the line buffer 22a.
It is stored as the binarized image data BID (I) (step R8).

That is, the system controller 21 again
The white reference plate 44 is scanned, and the image data when the white reference plate 44 is scanned is subjected to shading correction by the shading correction circuit 52 based on the white reference data in the line buffer 53, and then the digital image processing circuit. The data is binarized by the binarization threshold Th at 54 and stored as the binarized image data BID (I) in the line buffer 22a.

When the transfer of the binarized image data BID (I) to the line buffer 22a is completed, the system control unit 2
1 increments the pixel counter I by 1 (step R9) to determine whether the binarized image data BID (I) of the pixel indicated by the pixel counter I is “1”, that is, the black image data. If it is not black image data, it is checked whether the pixel counter I has counted one line (2048 pixels) (step R11).

At step R11, the system control unit 21
Returns to step R9 when the pixel counter I does not count for one line, increments the pixel counter I in the same manner as described above (step R9), and executes the next 2
Similarly, the binarized image data BID (I) is checked whether it is black image data (whether it is "1") (step R10).

If the binarized image data BID (I) of all the pixels in one line are white image data by performing the above-described processing sequentially (steps R9 to R11), the binarization threshold Th is increased by the above step α. The pixel counter I to "0"
(Step R12), the process returns to step R7, the white reference plate 44 is scanned again, shading correction and binarization are performed, and the binarized image data BID (I) is obtained.
Is stored in the line buffer 22a (steps R7 to R8), and the binary image data BID (I) stored in the line buffer 22a is sequentially checked as to whether it is black image data (steps R9 to R11). .

When all the binarized image data BID (I) are white image data by performing the same processing as described above (steps R9 to R11), the binarization threshold Th is again raised by the step α. Pixel counter I
Is cleared (step R12), and the same processing as described above is performed (steps R9 to R11).

When black image data appears in step R10 after performing the above processing, the process proceeds to step R13, the shading correction accuracy at that time is calculated (step R13), and the calculated shading correction accuracy is calculated in step R3. It is checked whether or not the correction accuracy determination level LV set in step 3 is exceeded (step R14).

When the calculated shading correction accuracy does not exceed the correction accuracy determination level LV in step R14, the system control unit 21 increments the counter N for counting the number of white reference data collections (step R15). The incremented counter N is
It is checked whether the upper limit TH of the number of white reference data collections set in step R2 has been exceeded, that is, whether the white reference data has been collected up to the preset upper limit TH of the number of white reference data collections (step R16).

At step R16, when the count number of the counter N does not exceed the upper limit TH of the number of white reference data collections, the system control section 21 causes the system control section 21 to perform step R5 of FIG.
15, the same processing as above is performed from the collection of the white reference data, and when the white reference data is collected, the initial binarization threshold UPTH is set again as the binarization threshold Th as shown in FIG. After the white reference plate 44 is scanned again (step R6) (step R7), the shading correction and binarization are performed and the binarized image data BID (I) is stored in the line buffer 22a as described above (step R7).
8) It is checked whether the binary image data BID (I) for one line includes black image data (steps R9 to R11).

Binary image data BID for one line
When the black image data is not included in (I) (steps R9 to R11), the system control unit 21 raises the binarization threshold Th by the step α (step R12). Similarly, the white reference plate 44 is scanned to check whether black image data is included in the binarized image data BID (I) that has been subjected to shading correction and binarization (steps R7 to R11), and in step P11, black When the image data appears, the system control unit 21 calculates the correction accuracy (step R13) and checks whether the calculated correction accuracy is higher than the correction accuracy determination level LV (step R14).

In step R14, when the calculated correction accuracy is lower than the correction accuracy determination level LV, the system control unit 21 increments the counter N in the same manner as described above to obtain the upper limit TH of the number of times of white reference data collection. Is checked (step R16), and if not exceeded, the process returns to step R5 and the same processing as described above is performed (steps R5 to R16).

Even though the white reference data was redone and shading correction processing was performed to eliminate the influence of noise and the like, the binarization threshold Th was gradually increased to check the shading correction accuracy. In step R14, when the upper limit TH of the number of times white reference data is collected is exceeded without obtaining the correction accuracy determination level LV, the system control unit 21 determines that the shading correction is appropriate because the optical system is deteriorated or soiled. When it is determined that the accuracy cannot be obtained, the fact is displayed and output on the display of the operation panel 30, and when necessary, a warning sound is generated and a warning is given to end the shading correction accuracy determination processing. (Step R17).

When the calculated correction accuracy exceeds the correction accuracy determination level LV in step R14, the system control unit 21 determines that the appropriate shading correction accuracy has been obtained, and the normal reading process of the original 41 is performed. Then, the shading correction determination process ends (step R18).

As described above, in this embodiment, after the white reference data is sampled, the white reference plate 44 is read again to perform shading correction and binarized image data BID (I). Each time, it is judged whether the image data is white image data or black image data, and the binarized image data BID of all one line
If (I) is white image data, only the ascending step α is 2
Raise the threshold value Th, scan the white reference plate 44 again,
It is checked whether or not black image data is included in the one-line binarized image data BID (I) that has been subjected to shading correction and binarization. If all the binarized image data BID (I) are white image data, the binarization threshold Th is increased again by the ascending step α, and the same check is performed.

Therefore, the facsimile apparatus can judge the shading correction accuracy more appropriately and accurately by the software processing without making a large-scale hardware change, and can judge the shading correction accuracy. 1 can be provided at low cost. In particular, the circuits in the scanner 24 and the line buffer 22a used in the determination processing of the shading correction accuracy in the present embodiment are provided in advance in a normal facsimile apparatus, and in particular, new hardware The shading correction accuracy can be determined without any addition.

16 to 18 are diagrams showing a sixth embodiment of the image reading apparatus of the present invention.
Image data obtained by scanning the white reference plate again is binarized while sequentially increasing the threshold value, and dust or scratches in the optical system are detected depending on whether there is black image data in one line of the binarized image data. The judgment is made by distinguishing it from the deterioration.

This embodiment is applied to an embodiment similar to the above-described first embodiment, and in the description of this embodiment, the reference numerals used in the above-mentioned first embodiment are used. The description will be given as it is.

In the present embodiment, as shown in FIG. 16, the system control unit 21 makes various initial settings when a reading instruction is given from the operation panel 30, and particularly, the counter N and the pixel counter I. Initialize the count value, the count value of the counter M that counts the number of black pixels, and the counter L that counts the number of lines (the number of lines where black image data is detected in the local area) (N = 0, I = 0, M =
0, L = 0) (step T1), setting of white reference data sampling frequency upper limit TH1, optical system dust / scratch determination frequency TH
2. Set initial binarization threshold UPTH and rising step α (step T2). Also in the present embodiment, assuming that the number of pixels for one line is 2048 pixels,
This will be described below.

Next, the system control unit 21 determines the original reading mode designated by the operation panel 30 and sets the correction accuracy determination level LV corresponding to the determined original reading mode (step T3), and the light source 45. Is turned on (step T4), the white reference plate 44 is scanned, and the image data obtained by scanning is stored in the line buffer 53 as white reference data (step T5).

Next, as shown in FIG. 17, the system control unit 21 sets the temporary binarization threshold Th as step T2.
The initial binarization threshold UPTH set in step S6 is set (step T6), the white reference plate 44 is scanned again, and the shading correction circuit 52 performs shading correction on the image data when the white reference plate 44 is scanned. Then, it is binarized by the digital image processing circuit 54 and stored in the line buffer 22a as binarized image data BID (I) (step T8).

When the transfer of the binarized image data BID (I) to the line buffer 22a is completed, the system control unit 2
1 increments the pixel counter I by 1 (step T9) to determine whether the binarized image data BID (I) of the pixel indicated by the pixel counter I is “1”, that is, the black image data. Is checked (step T10), and if it is black image data, the value of the pixel counter I indicating the appearance position of the black image data is held and the counter M is incremented (step T11). It is checked whether I has counted one line (2048 pixels) (step T1).
2). The value of the pixel counter I is held in the system memory 22, for example.

At step T10, when the binary image data BID (I) of the pixel indicated by the pixel counter I is not "1", that is, when it is white image data, the value of the pixel counter I is held and Without incrementing the counter M, the process proceeds to step T12, and it is checked whether or not the pixel counter I has counted one line (step T12).

At step T12, when the pixel counter I is not counting for one line, the process returns to step T9, the pixel counter I is incremented (step T9), and the next binary image data BID (I) is obtained. ,
Similarly, it is checked whether it is black image data (whether it is "1") (step T10).

The system control section 21 sequentially performs the above-mentioned processing to carry out the binarized image data BID of all the pixels on one line.
For (I), it is determined whether the image data is black image data or white image data, and for black image data, the value of the pixel counter I of the black image data and the counter M are incremented (step T11). , The value of the pixel counter I and the counter M are not incremented, the process proceeds to step T12 to check whether the processing for one line is completed (step T12), and the processing for one line is completed at step T12. Then, the counter M
Is positive (M> 0), that is, whether there is black image data in the binarized image data BID (I) in one line (step T13).

At step T13, when the black image data does not exist in the binarized image data BID (I) in one line, the binarization threshold Th is increased by the ascending step α and the pixel counter I Is cleared to "0" (step T14), the process returns to step T7, the white reference plate 44 is scanned again to perform shading correction and binarization,
The binarized image data BID (I) is transferred to the line buffer 22a.
To the line buffer 22 (steps T7 and T8).
The binary image data BID (I) stored in a is sequentially checked for black image data in the same manner as above, and if it is black image data, the value of the pixel counter I at which the black image data is generated is held. In addition, the counter M is incremented, and when it is not black image data,
The process proceeds to step T12 as it is, and it is checked whether the processing for one line has been performed (steps T9 to T12).

By performing the same processing as described above, all the binary image data BID (I) are white image data, and step T1
When M is not positive in 3, the binarization threshold Th is again increased by the increasing step α and the pixel counter I
Is cleared (step T14), and the same processing as described above is performed (steps T7 to T13).

When the above processing is performed and if the black image data appears in the binarized image data BID (I) for one line and the counter M is positive in step T13, the process proceeds to step T15, The shading correction accuracy at that time is calculated (step T15), and as shown in FIG. 18, it is checked whether the calculated shading correction accuracy exceeds the correction accuracy determination level LV set in step T3 of FIG. 16 (step T16). ).

When the calculated shading correction accuracy does not exceed the correction accuracy determination level LV in step T16, the system control unit 21 checks whether or not the black image data is re-detected in the local area (step T1).
7).

That is, the system control unit 21 determines whether or not the black image data is re-detected in the local area depending on whether or not the value of the pixel counter I held in step T11 is continuous for a predetermined number.

At step T17, when the black image data is not detected again in the local area, the counter N for counting the number of white reference data samplings is incremented (step T18), and the incremented counter N is counted.
However, it is checked whether the white reference data collection number upper limit TH1 set in step T2 of FIG. 16 has been exceeded, that is, whether white reference data has been collected up to a preset white reference data collection number upper limit TH1 ( Step T1
9).

At step T19, when the count number of the counter N does not exceed the upper limit TH1 of the number of white reference data collections, the system control unit 21 collects the white reference data up to the preset number of white reference data collections. If it is determined that the white reference data is not obtained, the process returns to step T5 of FIG. 16 and the same processing is performed from the collection of the white reference data to collect the white reference data.
After PTH is set as the binarization threshold Th (step T6), the white reference plate 44 is scanned again (step T6).
7) Similarly to the above, shading correction and binarization are performed to obtain the line buffer 2 as the binarized image data BID (I).
After storing in 2a (step T8), whether or not the black image data data is included in the binary image data BID (I) for one line, and if it is included, the black image data exists. While holding the value of the pixel counter I, the counter M that counts the number of appearances is incremented to check whether processing for one line has been performed (steps T9 to T12).

When processing for one line is performed and the black image data is not included in the binarized image data BID (I) in the one line, the system control unit 21 raises the binarization threshold Th. After increasing the binarization threshold Th by step α and resetting the pixel counter I (step T1
4) Similarly to the above, the white reference plate 44 is scanned to perform shading correction and binarized binarized image data BID.
It is checked whether (I) includes black image data. If it is included, the value of the pixel counter I is held and the counter M is incremented (steps T9 to T12).

After processing for one line, step T1
When the black image data is included in 3 and the value of the counter M is positive, the correction accuracy is calculated (step T15), and it is checked whether the calculated correction accuracy is higher than the correction accuracy determination level LV (step S15). T16).

If the calculated correction accuracy is lower than the correction accuracy determination level LV in step T16, the system control unit 21 checks whether the black image data is re-detected in the local area in the same manner as described above (step T17). ), When the black image data is not detected again in the local area, the counter N is incremented (step T18), and it is checked whether or not the upper limit TH1 of the number of white reference data sampling times is exceeded (step T19). If not, then Figure 1
The process similar to the above is performed by returning to step T5 of step 6 (step T5 to step T19).

Although the white reference data was redone and shading correction processing was performed to eliminate the influence of noise and the like, the binarization threshold Th was gradually increased to check the shading correction accuracy. In step T16, when the correction accuracy determination level LV cannot be obtained and the black image data is not re-detected in the local area and the upper limit TH1 of the number of white reference data collection times is exceeded, the system control unit 21 Then, it is determined that the S / N ratio is lowered due to the deterioration of the optical system, and a warning display is output to display that fact on the display of the operation panel 30 (step P20).

In step T17, when the black image data is re-detected in the local area, the system control unit 21
Increments a counter L that counts the number of lines in which black image data is detected in the local area (step T21), and the count number of the counter L is determined as the optical system dust / scratch determination set in step T2 of FIG. Number of times TH
It is checked whether the number exceeds 2 (step T22), and the count number of the counter L is the optical system dust / scratch determination number TH2.
If not, go to step T18,
After incrementing the counter N (step T1
8) It is checked whether or not the upper limit TH1 of the number of times of white reference data collection has been exceeded (step T19). Step T1
When the value of the counter N does not exceed the upper limit TH1 of the number of times white reference data is collected in 9, the system control unit 21
Returns to step T5 of FIG. 16 and performs the same processing as described above (step T5 to step T19, steps T21, T22).

At step T22, when the count number of the counter L exceeds the optical system dust / scratch determination count TH2, the system control unit 21 determines that the optical system has dust or scratches, and displays a message to that effect. Is displayed on the display of the operation panel 30, and when necessary, a warning sound is generated to give a warning and the shading correction accuracy determination processing is ended (step T2).
3).

When the calculated correction accuracy exceeds the correction accuracy determination level LV in step T16, the system control unit 21 determines that the appropriate shading correction accuracy is obtained, and the normal original 41 of the original 41 is read. The process shifts to the reading process, and the shading correction determination process ends (step T24).

As described above, in this embodiment, after the white reference data is sampled, the white reference plate 44 is read again to perform shading correction and binarized image data BID (I). Each time, it is judged whether the image data is white image data or black image data, and the binarized image data BID of all one line
If (I) is white image data, only the ascending step α is 2
Raise the threshold value Th, scan the white reference plate 44 again,
It is checked whether or not black image data is included in the one-line binarized image data BID (I) that has been subjected to shading correction and binarization. If all the binarized image data BID (I) are white image data, the binarization threshold Th is increased again by the ascending step α, and the same check is performed.

Binary image data B in one line
When the ID (I) contains black image data and the correction accuracy does not reach the correction accuracy determination level LV, the binary image data BID (I) in one line a predetermined number of times contains black image data. Then, it is checked whether the black image data is re-detected in the local area. If the black image data is not re-detected in the local area, it is determined that the S / N ratio is deteriorated due to the deterioration of the optical system, and that is Is displayed, and when the black image data is continuously re-detected in the local area for a predetermined line,
It is judged that dust is attached to the optical system or it is scratched, and a warning display to that effect is displayed.

That is, the black image data generated at a uniform level and at random is originally read by the reading system (optical system).
It is considered that it is a noise component (white noise) superimposed on the image. When this white noise becomes large, the S / N ratio of the optical system decreases, which may cause deterioration of image quality depending on the reading mode. There is. Also, if black image data is continuously detected in a specific area, it is considered that the optical system is locally abnormal, such as dust or scratches, and the reading system ( Although it is not the deterioration of the optical system itself, the image quality may be deteriorated depending on the reading mode.

Therefore, in the present embodiment, the shading correction is performed several times, and the binarization threshold Th is changed to include the black image data in the image data when the white reference plate 44 is read. In this case, depending on whether or not the black image data is continuously detected in the local area, the S / N ratio may be lowered due to deterioration of the optical system (reading system), or the optical system may be damaged or dust. It is determined if there is, and a message to that effect is displayed.

Therefore, it is easy to determine whether the optical system is deteriorated, whether it has scratches or dust, and
It can be easily known and appropriate maintenance processing can be performed.

As a result, the usability of the facsimile apparatus 1 can be improved and the image quality can be improved.

19 to 21 are views showing a seventh embodiment of the image reading apparatus of the present invention.
The image data obtained by scanning the white reference plate is binarized while sequentially increasing the binarization threshold value, and 2 in the case of reading a document based on the generation ratio of black image data in one line of the binarized image data. The threshold value is set.

This embodiment is applied to the same embodiment as the first embodiment, and in the description of this embodiment, the reference numerals used in FIGS. 1 and 2 are used as they are. Explain.

In the present embodiment, as shown in FIG. 19, the system control unit 21 makes various initial settings when a reading instruction is given from the operation panel 30 (step V
1), the setting of the black pixel detection number determination threshold TH, the initial binarization threshold UPTH, and the rising step α (step V
2). Also in the present embodiment, the following description will be made assuming that the number of pixels for one line is 2048 pixels.

Next, the system controller 21 turns on the light source 45 (step V3), scans the white reference plate 44,
The image data obtained by scanning is stored in the line buffer 53 as white reference data (step V4).

Next, as shown in FIG. 20, the system control unit 21 sets the temporary binarization threshold Th as step V2.
The counter L which sets the initial binarization threshold UPTH set in step (5) (step V5) and counts the count value of the pixel counter I and the number of times of generation of black image data (the number of pixels of black image data detected in one line). After resetting (setting to "0") (step V6), the white reference plate 44 is again set.
Is scanned (step V7), and the image data when the white reference plate 44 is scanned is converted into the shading correction circuit 52.
After the shading correction is performed by, the binarized image data BID (I) is binarized in the line buffer 22a.
(Step V8).

That is, the system controller 21 again
The white reference plate 44 is scanned, and the image data when the white reference plate 44 is scanned is subjected to shading correction by the shading correction circuit 52 based on the white reference data in the line buffer 53, and then the digital image processing circuit. The data is binarized by the binarization threshold Th at 54 and stored as the binarized image data BID (I) in the line buffer 22a.

When the transfer of the binarized image data BID (I) to the line buffer 22a is completed, the system control unit 2
1 increments the pixel counter I by 1 (step V9) to determine whether the binarized image data BID (I) of the pixel indicated by the pixel counter I is “1”, that is, the black image data. If it is black image data, the counter L is incremented (step V11), and it is checked whether the value of the counter L exceeds the black pixel detection number determination threshold TH (step V12). ).

When the value of the counter L does not exceed the black pixel detection number determination threshold value TH in step V12, it is checked whether or not the pixel counter I has counted one line (2048 pixels) (step V13).
Is not counting for one line, step V
9, the pixel counter I is incremented (step V9), and the next binary image data BID (I) is similarly checked whether it is black image data (whether it is "1") (step V10). ).

The system control unit 21 sequentially performs the above-mentioned processing to execute the binarized image data BID of all the pixels on one line.
For (I), it is determined whether the image data is black image data or white image data, and for black image data, the counter L is incremented (step V11) so that the value of the counter L exceeds the black pixel detection number determination threshold TH. If checked (step V12) and the number of appearances of black image data has not reached the set black pixel detection number determination threshold TH, the above process is repeated.

In step V13, when the processing for one line is completed without the number of appearances of the black image data reaching the set threshold value TH for determining the number of black pixels, the binarization threshold value Th is set.
Is increased by the ascending step α (step V14), the process returns to step V6, and the same processing as described above is performed.

A white reference plate 44 newly loaded with the above processing
When the number of appearances of the black image data, which is the count value of the counter L, exceeds the black pixel detection number determination threshold TH in step V12, it is preset based on the number of appearances of the black image data. The binarization threshold is set as a binarization threshold for reading the document 41 (step V15), and the document 41 based on the set binarization threshold is set.
Is read (step V16).

As the binarization threshold value at the time of reading the original document 41, for example, the binarization threshold value at the time of reading the original document 41 when the shading correction is performed in a completely satisfactory state is set to the maximum level of the image data. If the value is set to 50% of the value, a binarization threshold lower than the 50% value is set according to the number of appearances of black image data.

Therefore, after the shading correction of the image data when the white reference plate 44 is read for the magnitude of the noise level due to the deterioration of the reading system, the binarization threshold Th is changed and the black image data at that time is changed. The number of occurrences is determined, and the binarization threshold at the time of reading the document 41 can be lowered and binarized according to the noise level, and the background stain due to noise can be prevented and the image quality can be improved. You can

That is, as shown in FIG. 21A, when the scanning waveform of the image data when the white reference plate 33 is rescanned has a level drop due to background stains or the like, the original reading according to the present embodiment is performed. If high-density original reading is performed at the binarization threshold TH without performing the binarization threshold setting process at that time, an image binarized at the binarization threshold TH as shown in FIG. Black image data due to background stains will appear in the data. However, when the binarization threshold value setting process at the time of reading an original according to the present embodiment is performed, as shown in FIG. 21C, based on the number of generations of black image data when the white reference plate 44 is rescanned. The binarization threshold value at the time of reading the document can be binarized by lowering the binarization threshold value TH from the binarization threshold value TH ′ to the binarization threshold value TH ′. Can be prevented from being included in the image quality and the image quality can be improved.

22 to 23 are views showing an eighth embodiment of the image reading apparatus of the present invention.
The image data obtained by scanning the white reference plate is binarized while sequentially increasing the binarization threshold value, and the image data obtained by reading the document based on the generation ratio of the black image data in one line of the binarized image data. The number of gradations for halftone processing is set.

This embodiment is applied to the same embodiment as the first embodiment, and the reference numerals used in FIGS. 1 and 2 are used as they are in the description of this embodiment. Explain.

In this embodiment, as shown in FIG. 22, the system control unit 21 makes various initial settings when a reading instruction is given from the operation panel 30 (step W).
1), the setting of the black pixel detection number determination threshold TH, the initial binarization threshold UPTH, and the rising step α (step V
2). Also in the present embodiment, the following description will be made assuming that the number of pixels for one line is 2048 pixels.

Next, the system controller 21 sets the gradation number determination thresholds TH1 and TH2 (step W3), and the light source 4
5 is turned on (step W4), the white reference plate 44 is scanned, and the image data obtained by scanning is stored in the line buffer 53 as white reference data (step W5). Note that the gradation number determination threshold TH1 and the gradation number determination threshold TH2 are TH
1> TH2.

Next, as shown in FIG. 23, the system control section 21 sets the temporary binarization threshold Th as the above-mentioned step W2.
The counter L which sets the initial binarization threshold UPTH set in step (6) (step W6) and counts the count value of the pixel counter I and the number of occurrences of black image data (the number of pixels of black image data detected in one line). After resetting (setting to "0") (step W7), the white reference plate 44 is again set.
Is scanned (step W7), and the image data when the white reference plate 44 is scanned is converted into the shading correction circuit 52.
Shading correction is performed by the digital image processing circuit 54 and binarized by the digital image processing circuit 54.
The binary image data BID (I) is stored in a (step W9).

When the transfer of the binarized image data BID (I) to the line buffer 22a is completed, the system control unit 2
1 increments the pixel counter I by 1 (step W10) to determine whether the binarized image data BID (I) of the pixel indicated by the pixel counter I is “1”, that is, the black image data. If it is black image data, the counter L is incremented (step W12), and it is checked whether the value of the counter L exceeds the black pixel detection number determination threshold TH (step W13). ).

At step W13, when the value of the counter L does not exceed the black pixel detection number determination threshold TH, it is checked whether or not the pixel counter I has counted one line (2048 pixels) (step W14).
Is not counting for one line, step W
10, the pixel counter I is incremented (step W10), and the next binarized image data BID
Similarly, for (I), it is checked whether the image data is black image data (whether it is "1") (step W11).

The system control unit 21 sequentially performs the above-mentioned processing to execute the binarized image data BID of all the pixels on one line.
With respect to (I), it is determined whether the image data is black image data or white image data, and for black image data, the counter L is incremented to check whether the value of the counter L exceeds the black pixel detection number determination threshold TH. When the number of appearances of the image data has not reached the set black pixel detection number determination threshold TH, the above process is repeated (steps W10 to W14).

At step W14, when the processing for one line is completed without the number of appearances of the black image data reaching the set threshold value TH for determining the number of black pixels, the binarization threshold Th is set.
Is increased by the ascending step α (step W15), the process returns to step W7, and the same processing as described above is performed.

The system control unit 21 performs the above processing on the newly read image data of the white reference plate 44, and in step W13, the number of appearances of the black image data, which is the count value of the counter L, is the black pixel detection number determination threshold value. When TH exceeds TH, the binarization threshold Th at which black image data that exceeds the black pixel detection number determination threshold TH appears is step W in FIG.
It is checked whether it is higher than the high gradation number determination threshold TH1 set in 3 (Th> TH1) (step W16), 2
When the binarization threshold value Th is higher than the gradation number determination threshold value TH1, it is determined that the optical system is not deteriorated and the shading correction is properly performed, and the intermediate value of the image data obtained by reading the document 41 is determined. 64, the highest number of gradations
The gradation is set (step W17).

In step W16, the binarization threshold Th is set.
Is lower than the gradation number determination threshold TH1, the system control unit 21 is higher than the low gradation number determination threshold TH2 set in step W3 of FIG. 22 (Th> TH2).
Is checked (step W18), and when the binarization threshold Th is higher than the gradation number determination threshold TH2, the optical system has deteriorated, but it is determined that the degree of deterioration is low, and the original 41 is read. 32 gradations are set as the gradation number of the halftone processing of the read image data (step W19).

Further, in step W18, the binarization threshold value T
When h is a value lower than the gradation number determination threshold TH2, the system control unit 21 determines that the deterioration of the optical system is severe, and sets 16 as the gradation number of the halftone processing of the image data obtained by reading the document 41. The gradation is set (step W20).

When the setting of the number of gradations is completed, the system control unit 21 performs the reading process of the original 41, and the halftone processing of the image data of the original 41 is set by the digital image processing circuit 54. The halftone process is performed according to the key number, and the shading correction accuracy determination process ends (step W21).

Therefore, after shading correction of the image data when the white reference plate 44 is read, the binarization threshold Th is changed, and the noise level is large due to the deterioration of the reading system depending on the number of black image data generated at that time. It is possible to set the number of gradations of the halftone processing when the document 41 is read, in accordance with the noise level.
Appropriate halftone processing can be performed according to the degree of deterioration of the optical system. As a result, it is possible to improve the image quality when performing halftone processing.

That is, when halftone processing is performed on an image obtained by reading the original 41, even if the reading system deteriorates and there is a large noise component, if high-gradation processing is performed, the noise component is also grayed out. There is a risk of soiling.

However, in the present embodiment, since the number of gradations is changed according to the degree of deterioration of the reading system,
Although the image quality is deteriorated due to the decrease in the number of gradations, the noise component can be removed, and the image quality can be improved.

Although the invention made by the present inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

For example, in each of the above embodiments, the case where the invention is applied to the facsimile device 20 has been described. However, the invention is not limited to the facsimile device and can be applied to general image reading devices that perform shading correction.

Further, in the seventh and eighth embodiments, when the shading correction accuracy is poor, the binarization threshold value is changed and the number of gradations is set without performing the warning process. The warning process may be performed. By doing so, the maintainability can be improved and the usability of the facsimile device 20 can be improved.

[0256]

According to the image reading apparatus of the present invention, the correction accuracy of the shading correction can be determined before scanning the original, and the quality due to deterioration of the optical system, dust, scratches, etc. can be determined. It is possible to prevent deterioration in advance and improve the image quality.

According to the image reading apparatus of the second aspect of the present invention, the shading correction accuracy can be determined based on the binarized image data, and the image processing steps of the ordinary image reading apparatus can be used. It is possible to determine the shading correction accuracy. As a result, the shading correction accuracy determination process can be made simple and easy.

According to the image reading apparatus of the third aspect, the image data of the white reference member subjected to the shading correction is binarized by changing the binarization threshold value and binarizing the image data a predetermined number of times. The shading correction accuracy can be determined based on the image data, and more precise shading correction accuracy can be determined.

According to the image reading apparatus of the fourth aspect, when the binarization threshold value is increased from a low value,
The appearance of black image data in the binarized image data can be monitored, and the shading correction accuracy can be determined based on the binarization threshold value at that time, and the shading correction accuracy can be determined more accurately and easily. can do.

According to the image reading apparatus of the fifth aspect, when the binarization threshold is lowered from a high value,
By monitoring the binarized image data, the shading correction accuracy can be determined based on the binarized threshold value when all the white image data is obtained, and when the deterioration of the optical system is small,
The shading correction accuracy can be determined more quickly and with high accuracy.

According to the image reading apparatus of the present invention, the appearance of the black image data when the binarization threshold is changed and binarized, for example, the increase rate and the decrease rate of the black image data. The shading correction accuracy can be determined based on this, and the shading correction accuracy can be determined more accurately and easily.

According to the image reading apparatus of the seventh aspect, the shading correction determination process is performed a plurality of times to perform the shading determination while avoiding the influence of transient disturbance such as noise. When the reference correction accuracy cannot be obtained despite the reduction of noise and the like, a warning can be output and it can be recognized that there is an abnormality in the optical system. As a result, the abnormality of the optical system can be managed more appropriately, the restoration can be promoted, and the image quality can be improved.

According to the image reading apparatus of the present invention, it is possible to monitor the shading correction accuracy according to the original reading mode, improve the image quality at the time of reading the original, and appropriately manage the optical system. It can be performed.

According to the image reading apparatus of the present invention, when the original is scanned before the original is scanned based on the result of binarizing the image data obtained by scanning the white reference member and performing shading correction. The image quality of can be predicted and determined in advance, and the image quality can be improved.

According to the image reading apparatus of the tenth aspect of the present invention, the appearance of the black image data when the binarization threshold value is changed and binarized, for example, the increase rate and the decrease rate of the black image data. Image quality can be determined based on
The image quality can be determined more accurately and easily.

According to the image reading apparatus of the eleventh aspect of the present invention, the image quality determination process is performed a plurality of times, and the image quality determination process is performed while avoiding the influence of transient disturbance such as noise. In addition, it is possible to output a warning and to recognize that there is an abnormality in the optical system when an appropriate image quality cannot be obtained despite reducing noise and the like. . As a result, the abnormality of the optical system can be managed more appropriately, restoration can be promoted, and image quality can be improved.

According to the image reading apparatus of the twelfth aspect, when there is an abnormality in the optical system, it is determined whether it is due to deterioration of the optical system or due to scratches or dust. Therefore, the abnormality of the optical system can be determined more appropriately. As a result, the optical system can be repaired more appropriately.

According to the image reading apparatus of the thirteenth aspect, it is possible to determine the image quality according to the document reading mode, and it is possible to perform more appropriate determination of the image quality.

According to the image reading apparatus of the fourteenth aspect of the present invention, the binarization threshold value when binarizing the image data obtained by actually scanning the original is used as the image quality judgment result, that is, the shading correction accuracy. Can be changed according to
It is possible to prevent / reduce the occurrence of black streaks and background stains in the binarized image and improve the image quality.

According to the image reading apparatus of the fifteenth aspect of the present invention, the number of gradations at the time of gradation processing of the image data obtained by actually scanning the original is determined according to the image quality judgment result, that is, the shading correction accuracy. The image quality can be improved by preventing and reducing the occurrence of background stains in the halftone image.

According to the image reading apparatus of the sixteenth aspect of the present invention, it is possible to perform the determination processing of the presence / absence of the black image data and the generation rate thereof at high speed while reducing the load on the software. The processing speed of the image reading device can be improved.

According to the image reading apparatus of the seventeenth aspect, it is not necessary to add another circuit for performing the determination process of the presence / absence of the black image data and the generation rate thereof, and the image reading apparatus is inexpensive. Can be one.

According to the image reading apparatus of the eighteenth aspect of the invention, image processing can be performed according to the image quality judgment result, that is, the shading correction accuracy, and when the shading correction accuracy is lowered. Also, the image quality can be improved by performing appropriate image processing.

According to the image reading apparatus of the nineteenth aspect, it is possible to manage the shading correction accuracy or the image quality while improving the processing speed of the image reading apparatus.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a facsimile apparatus to which an image reading apparatus according to a first embodiment of the present invention is applied.

FIG. 2 is a configuration diagram of a main part of the scanner of FIG.

3 is a flowchart showing shading correction accuracy determination processing and image quality determination processing by the facsimile apparatus of FIG.

FIG. 4 is a flowchart showing shading correction accuracy determination processing and image quality determination processing according to the second embodiment of the image reading apparatus of the present invention.

FIG. 5 is a flowchart showing a process subsequent to the shading correction accuracy determination process and the image quality determination process of FIG.

FIG. 6 shows a waveform and a binarization threshold value at the time of rescanning the white reference plate for explaining the operations of the shading correction accuracy determination processing and the image quality determination processing of FIGS. 4 and 5 when the shading correction accuracy is good. Fig.

FIG. 7 is a diagram showing a waveform and a binarization threshold at the time of rescanning the white reference plate for explaining the operations of the shading correction accuracy determination processing and the image quality determination processing of FIGS. 4 and 5 when the shading correction accuracy is poor. .

FIG. 8 is a flowchart showing shading correction accuracy determination processing and image quality determination processing according to the third embodiment of the image reading apparatus of the present invention.

9 is a flowchart showing a process subsequent to the shading correction accuracy determination process and the image quality determination process of FIG.

FIG. 10 is a diagram when the shading correction accuracy is good.
FIG. 10 is a diagram showing a waveform and a binarization threshold value at the time of rescanning the white reference plate for explaining the operations of the shading correction accuracy determination process and the image quality determination process of FIG. 9.

FIG. 11 is a diagram showing a waveform and a binarization threshold value at the time of rescanning the white reference plate for explaining the operations of the shading correction accuracy determination processing and the image quality determination processing of FIGS. .

FIG. 12 is a circuit configuration diagram of a black pixel detecting / counting circuit of a scanner according to a fourth embodiment of the image reading apparatus of the invention.

FIG. 13 is a timing chart of signals of respective parts of the black pixel detecting / counting circuit in FIG.

FIG. 14 is a flowchart showing shading correction accuracy determination processing and image quality determination processing according to the fifth embodiment of the image reading apparatus of the present invention.

FIG. 15 is a flowchart showing a process subsequent to the shading correction accuracy determination process and the image quality determination process of FIG.

FIG. 16 is a flowchart showing shading correction accuracy determination processing and image quality determination processing according to the sixth embodiment of the image reading apparatus of the present invention.

FIG. 17 is a flowchart showing a process subsequent to the shading correction accuracy determination process and the image quality determination process of FIG. 16;

FIG. 18 is a flowchart showing a process subsequent to the shading correction accuracy determination process and the image quality determination process of FIG. 17;

FIG. 19 is a flowchart showing a shading correction accuracy determination process and an image quality determination process for setting a binarization threshold value at the time of reading an original according to the seventh embodiment of the image reading apparatus of the present invention.

FIG. 20 is a flowchart showing a process that follows the shading correction accuracy determination process and the image quality determination process of FIG. 19;

21 is a waveform (a) of image data of the white reference plate read by the shading correction accuracy determination processing and the image quality determination processing of FIGS. 19 and 20, a waveform of image data at the time of reading an original, and shading correction accuracy determination. The figure which compares and shows the binarization threshold value (b) before being set by the processing and the image quality determination processing and the binarization threshold value (c) set by the shading correction accuracy determination processing and the image quality determination processing.

FIG. 22 is a flowchart showing shading correction accuracy determination processing and image quality determination processing for setting the number of gradations in halftone processing according to the eighth embodiment of the image reading apparatus of the present invention.

FIG. 23 is a flowchart showing a process subsequent to the shading correction accuracy determination process and the image quality determination process of FIG. 22.

FIG. 24 is a configuration diagram of main parts of a conventional image reading apparatus.

[Explanation of symbols]

 20 Facsimile device 21 System control unit 22 System memory 22a Line buffer 23 Parameter memory 24 Scanner 25 Plotter 26 Network control unit 27 Modem 28 Image memory 29 Encoding / decoding unit 30 Operation panel 31 Bus 41 Original document 42 Guide member 43 Target glass 44 White reference plate 45 Light source 46 Mirror 47 Lens 48 Image sensor 49 Amplifier 50 A / D converter 51 Peak hold circuit 52 Shading correction circuit 53 Line buffer 54 Digital image processing circuit 60 Black pixel detection / counting circuit 61 AND circuit 62 Counter 63 Host The interface

Claims (19)

[Claims] 1. A scanning means for scanning a white reference member and an original using an optical system, and a white reference data storage means for storing white reference data in pixel units obtained by the scanning means scanning the white reference member. A shading correction unit that performs shading correction of shading distortion due to the optical system on image data obtained by scanning by the scanning unit based on the white reference data; and various types of image data that are shading corrected by the shading correction unit. An image reading apparatus comprising image processing means for performing image processing, wherein the scanning means scans the white reference member to store the white reference data in the white reference data storage means, and then the scanning means , The image data obtained by scanning the white reference member again before scanning the original, and scanning the white reference member Control means for performing shading correction by the shading correction means based on the white reference data; determination means for determining the shading correction accuracy based on the image data of the white reference member that has been shading corrected by the shading correction means; An image reading apparatus comprising: 2. A scanning means for scanning a white reference member and an original using an optical system, and a white reference data storage means for storing white reference data in pixel units obtained by the scanning means scanning the white reference member. A shading correction unit that performs shading correction of shading distortion due to the optical system on image data obtained by scanning by the scanning unit based on the white reference data; and various types of image data that are shading corrected by the shading correction unit. An image reading apparatus comprising image processing means for performing image processing, wherein the scanning means scans the white reference member to store the white reference data in the white reference data storage means, and then the scanning means , The image data obtained by scanning the white reference member again before scanning the original, and scanning the white reference member After the shading correction is performed by the shading correction means based on the white reference data, the image processing means is binarized by a predetermined binarization threshold, and the white reference member subjected to the shading correction by the shading correction means. Determining means for determining the shading correction accuracy based on the binarized image data obtained by binarizing the image data by the image processing means with a predetermined binarization threshold value. Image reading device. 3. The image processing means binarizes the image data of the white reference member, which has been shading-corrected by the shading correction means, by sequentially changing the binarization threshold value and binarizing the image data a predetermined number of times. 3. The image reading apparatus according to claim 2, wherein the image processing unit determines the shading correction accuracy based on the binarized image data that is binarized by changing the binarization threshold value. 4. The image processing means performs the binarization by sequentially increasing the binarization threshold value from a predetermined low value at predetermined intervals, and the determination means includes the binarization processing performed by the image processing means. Increase the threshold value in sequence to 2
The image reading apparatus according to claim 2, wherein the shading correction accuracy is determined based on the binarization threshold value when black image data first appears in the binarized image data. 5. The image processing means performs the binarization by sequentially lowering the binarization threshold value from a predetermined high value at predetermined intervals, and the determination means includes the binarization threshold value of the image processing means. 3. The shading correction accuracy is determined based on the binarization threshold value when the binarized image data binarized by sequentially lowering the image data all become white image data for the first time. Image reading device. 6. The image processing means performs the binarization by gradually lowering the binarization threshold value from a predetermined high value at predetermined intervals or by sequentially increasing it from a predetermined low value at predetermined intervals. The determining unit determines the shading correction accuracy based on the appearance of black image data when the image processing unit sequentially lowers or raises the binarization threshold value to perform the binarization. The image reading apparatus according to claim 2, wherein: 7. The shading correction determination means for controlling the shading correction from the scan for collecting the white reference data by the scanning means when the shading correction accuracy judged by the judging means is less than a predetermined reference correction accuracy. If the shading correction accuracy of the judgment result of performing the processing and performing the shading correction judgment processing a predetermined number of times is less than or equal to the reference correction accuracy, a warning that the optical system has an abnormality is output. The image reading device according to any one of claims 1 to 6. 8. The image reading apparatus according to claim 7, wherein the determination unit changes the reference correction accuracy according to a document reading mode such as a halftone reading mode or a simple binary reading mode. 9. A scanning means for scanning a white reference member and an original using an optical system, and a white reference data storage means for storing white reference data in pixel units obtained by the scanning means scanning the white reference member. A shading correction unit that performs shading correction of shading distortion due to the optical system on image data obtained by scanning by the scanning unit based on the white reference data; and various types of image data that are shading corrected by the shading correction unit. An image reading apparatus comprising image processing means for performing image processing, wherein the scanning means scans the white reference member to store the white reference data in the white reference data storage means, and then the scanning means , The image obtained by scanning the white reference member again a predetermined number of times before scanning the original document. After shading correction of the data by the shading correction means, the image processing means causes the binarization threshold value to be sequentially increased from a predetermined high value at predetermined intervals every time the scanning means scans the white reference member. Or a control means for sequentially lowering the value from a predetermined low value at a predetermined interval to binarize, and image data obtained by the image processing means by sequentially raising or lowering the binarization threshold value to be binarized. The image quality when the scanning unit scans the document is determined based on the binarization threshold when the image data is entirely white for the first time or the binarization threshold when the black image data first appears. An image reading apparatus comprising: a determination unit that performs the determination. 10. The determination means is based on the appearance of black image data in the binarized image data binarized by the image processing means by raising or lowering the binarization threshold value. The image reading apparatus according to claim 9, wherein the image quality is determined. 11. The control means, when the binarization threshold value is equal to or less than a predetermined reference threshold value, causes the scanning means to perform the image quality determination processing from a scan for collecting the white reference data, and 11. The image reading apparatus according to claim 10, wherein if any of the determination results obtained by performing the image quality determination processing a predetermined number of times is equal to or less than the reference threshold value, a warning indicating that the optical system has an abnormality is output. 12. The image reading device further comprises black pixel appearance position storage means for storing the appearance position of the black image data when the binarization threshold value is raised or lowered. When the appearance positions of the black image data stored in the black pixel appearance position storage means are continuous in a predetermined local area, it is determined that the optical system has an abnormality such as a scratch or dust. The image reading device according to claim 2. 13. The determination means changes the determination criterion for determining the image quality according to a document reading mode such as a halftone reading mode or a simple binary reading mode. The image reading device according to claim 9. 14. The control means changes a binarization threshold value when the image processing means binarizes image data obtained by scanning the document based on the determination result of the determination means. The image reading device according to any one of claims 9 to 13. 15. The image processing means subjects the image data obtained by reading the original document to gradation processing to a predetermined gradation, and the control means carries out the image processing based on the judgment result of the image quality of the judgment means. 14. The image reading apparatus according to claim 9, wherein the number of gradations during the gradation processing by the means is changed. 16. The judging means counts the judging circuit for judging whether the binarized image data of the white reference member is black image data, and the black image data judged by the judging circuit. 16. The image reading apparatus according to claim 4, further comprising: a counter for controlling whether or not the black image data is generated, and processing for determining a generation ratio of the black image data is performed by hardware. . 17. The determination means is configured to determine whether the black pixel is included in the binarized image data of the white reference member or the generation ratio of the black image data is processed by software. The image reading device according to any one of claims 2 to 15. 18. A scanning means for scanning a white reference member and an original by using an optical system, and a white reference data storage means for storing white reference data in pixel units obtained by the scanning means scanning the white reference member. A shading correction unit that performs shading correction of the shading distortion of the optical system on the image data obtained by scanning by the scanning unit based on the white reference data; and various types of image data that are shading corrected by the shading correction unit. An image reading apparatus comprising: an image processing unit that performs various image processes based on processing parameters; After the scanning, the white reference member is scanned before the scanning unit scans the document, and the white reference member is scanned. Control means for performing shading correction of the image data obtained by scanning by the shading correction means based on the white reference data; and based on a correction result when the image data of the white reference member is subjected to shading correction by the shading correction means. The image data obtained by scanning the document based on the determination result of the determination unit. An image reading apparatus, wherein the processing parameter of the image processing means is changed. 19. The control unit according to claim 1, wherein the control unit executes the shading correction accuracy determination process or the image quality determination process at predetermined intervals. Image reading device.