JPH0965122A - Image processing device - Google Patents

Abstract

(57) [Abstract] [Object] The present invention is capable of performing shading correction that is extremely less affected by dust, dirt, or deterioration of the light amount on the white reference surface, and is an image processing apparatus with high image quality and excellent durability. The purpose is to provide. [Configuration] From a white reference data storage unit 105 that stores and holds image data of one line of white reference plane, an average value calculation unit 2 that calculates an average value of image data of one line, and an average value calculation unit 2 The average value storage unit 4 that stores the average value of the white reference data storage unit 105 that is calculated by the average value calculation unit 2
Subtraction unit 5 for calculating the difference between the average value of the white reference data and the average value of the image data of the white reference plane, and the setting unit 6 for setting the allowable value.
And a comparison unit 7 that compares the difference calculated by the subtraction unit 5 with the allowable value of the setting unit 6, and if the difference exceeds the allowable value, 1
The image data of the white reference plane of the line is stored in the white reference data storage unit 1.
05, and a control unit 8 for performing rewriting and storage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for performing shading correction on an image signal obtained by optically reading a document or the like.

[0002]

2. Description of the Related Art In recent years, due to the progress of multimedia and the like,
With the development of an image processing apparatus having a high-resolution image reading unit and a large-screen, high-resolution display apparatus, high-quality images have been handled. In an image processing apparatus, when binarizing image data read from a document using an image reading unit, shading correction is generally performed to perform shading distortion due to a light source, a lens, a light receiving element, or the like.

A conventional image processing apparatus will be described below. FIG. 5 is a schematic sectional view showing a configuration of an optical system of a reading unit of a conventional image processing apparatus. Reference numeral 301 denotes a white reference plane which is white reference data for performing shading correction, and 302
Is a glass on which a document 307, which will be described later, serving as a reference plane of the depth of focus is placed, 303 is a light source including a fluorescent lamp or an LED for irradiating the document 307 with light, and 304 is a document 307 provided in the reduction optical system. A mirror that bends the traveling direction of the reflected light from the white reference surface 310, a lens 305 that condenses the reflected light from the original 307 on an image sensor 306 described later, and 3
Reference numeral 06 is an image sensor including a photoelectric conversion element that converts the amount of reflected light into an electric signal, and 307 is a document that is converted into image data. When reading the white reference surface 301 and the original 307, the light source 303 is turned on, and the information of the original 307 or the like at the reading position is reflected by the mirror 304 and then passes through the lens 305 to reach the image sensor, as indicated by the broken line. At 306, it is photoelectrically converted into an electric signal. With this configuration, when the document 307 is scanned, the white reference surface 301 can be read at any time immediately before reading.

Next, the function of the conventional image processing apparatus will be described. FIG. 6 is a block diagram showing the configuration of a conventional image processing apparatus. 101 is an input terminal to which an analog signal read by the image sensor 306 is input; 102 is an A / D converter for converting the analog signal into a digital signal;
A control unit 103 controls a switch 104 and a white reference data storage unit 105 described later. Reference numeral 104 denotes a switch. When the white reference data storage unit 105 stores the white reference data, the digital signal line from the A / D converter 102 is connected to the white reference data storage unit 105, and when the original is read, A / The digital signal from the D converter 102 is connected to the shading correction circuit 106. Reference numeral 105 denotes a white reference data storage unit that stores previously read information of the white reference surface 301, and reference numeral 106 sequentially displays image data of one line of the original 307 that is read based on the white reference data stored in the white reference data storage unit 105. A shading correction circuit that performs shading correction, and 107 is an output terminal for image data of the original 307 that has been subjected to shading correction.

The operation of the image processing apparatus configured as described above will be described below. First, the white reference surface 301
Image data is photoelectrically converted by the image sensor 306 and input to the input terminal 101. The image signal of the white reference surface 301 input from the input terminal 101 is converted into a digital signal by the A / D converter 102, and then the switch 104.
Is input to Here, the switch 104 is switched to the A side shown in FIG. 6, and the image data of the white reference plane 301 is stored in the white reference data storage unit 105. Next, the manuscript 307
When reading, the image data of the original 307 is photoelectrically converted by the image sensor 306 and input to the input terminal 101. The image data of the document 307 input from the input terminal 101 is converted into a digital signal by the A / D converter 102, and then input to the switch 104. Switch 1 here
04 has been switched to the B side shown in FIG.
The image data of No. 7 is input to the shading correction circuit 106. The shading correction circuit 106 performs shading correction for correcting the image data of the document 307 by using the white reference data of the white reference data storage unit 105. The data after the shading correction is output from the output terminal 107.

Regarding the image processing apparatus that operates as described above, the flow of image data processing will be described below.
FIG. 7A is an example of a signal waveform of image data of one line when a white reference surface is read, and FIG. 7B is an example of a signal waveform of image data of one line when a white document is read. ,
FIG. 7C is an example of a signal waveform of the image data after the shading correction by the image data of FIGS. 7A and 7B. As shown in FIG. 7C, when the normal shading correction is performed, all the image data of the white document show a uniform value, and a high quality image can be obtained.

[0007]

However, in the above-mentioned conventional configuration, for example, when the information of the white reference plane is stored in the white reference data storage section, it is sequentially performed immediately before reading the original. In this case, if dust or dirt adheres to the white reference surface, improper shading correction will be performed on the image data of the original, and streaks will appear in the reproduced image, adversely affecting the image quality. Was there.

FIG. 8A shows an example of a signal waveform of image data of one line when a white reference surface on which dust or dirt adheres is read, and FIG. 8B shows one when a white original is read. 8C is an example of a signal waveform of image data of a line, and FIG.
It is an example of a signal waveform of image data after shading correction by both image data of (a) and (b). FIG.
As shown in (c), a non-uniform portion appears in all pixel data of the white document, an error occurs, and the image quality deteriorates. Therefore, in order to eliminate the influence of dust and dirt, there is a method of storing the image data of the white reference surface in the white reference data storage unit before the white reference surface is contaminated, for example, at the time of factory shipment. This method is not affected by dirt on the dust, but when the light amount of the light source is deteriorated due to aging or the like, the image data of the document becomes dark, or the image data of the document has a pattern indicating local deterioration of the light source. However, there is a problem in that the image quality deteriorates such as appearing. FIG. 9A shows an example of a signal waveform of image data of one line when the white reference plane is read. The broken line shows before deterioration of the light source and the solid line shows after deterioration of the light source. FIG. 9B is an example of a signal waveform of image data of one line when a white original is read after the light amount is deteriorated, and FIG. 9C is shown in FIG.
It is a signal waveform of image data after shading correction by both image data of (b). As shown in FIG. 9C, all pixel data of the white document does not have a uniform value but shows a nonuniform and lower value, which causes an error and also deteriorates the image quality. .

The present invention solves the above-mentioned problems of the prior art, and enables shading correction to be carried out with little influence of deterioration such as dust, dirt, and light quantity on the white reference surface, and high image quality and excellent durability. It is an object of the present invention to provide an image processing device.

[0010]

In order to achieve this object, an image processing apparatus according to a first aspect of the present invention has a white reference plane of one line and sequentially reads image data for each line to perform shading correction. An image processing device for performing
A white reference data storage unit that stores and holds the image data of the white reference surface of the line, an average value calculation unit that calculates the average value of the image data of one line, and an average that stores the average value from the average value calculation unit. A value storage unit, a subtraction unit that calculates the difference between the white reference data average value of the white reference data storage unit calculated by the average value calculation unit and the image data average value of the white reference surface, and a setting unit that sets the allowable value. And a comparison unit that compares the difference calculated by the subtraction unit with the allowable value of the setting unit, and if the difference exceeds the allowable value, write the image data of the white reference plane of one line in the white reference data storage unit. And a control unit for switching.

An image processing apparatus according to a second aspect is an image processing apparatus having a white reference surface of one line and sequentially reading image data line by line to perform shading correction.
Shading correction is performed by the white reference data storage unit that stores and holds one line of white reference plane image data as white reference data, and the white reference plane image data by the white reference data stored in the white reference data storage unit. A detection unit that detects the maximum value and the minimum value of the image data, a subtraction unit that calculates the difference between the maximum value and the minimum value, a setting unit that sets an allowable value, and a difference calculated by the subtraction unit and the tolerance of the setting unit. And a control unit that rewrites the image data of one line of the white reference plane to the white reference data storage unit when the difference exceeds the allowable value. There is.

[0012]

With this configuration, the white reference data storage unit that stores and holds the image data of the white reference surface of one line, and the average value calculation unit that calculates the average value of the image data of one line,
An average value storage unit that stores the average value from the average value calculation unit,
The subtraction unit that calculates the difference between the white reference data average value of the white reference data storage unit calculated by the average value calculation unit and the image data average value of the white reference surface, the setting unit that sets the allowable value, and the subtraction unit A comparison unit that compares the calculated difference with the allowable value of the setting unit, and a control unit that rewrites and stores the image data of one line of the white reference plane in the white reference data storage unit when the difference exceeds the allowable value. First, the white reference surface is read before the white reference surface becomes dirty, and the image data of one line of the white reference surface is stored in the white reference data storage unit, and the average value of one line at that time is stored as an average value. Accumulate in each section. When sequentially reading originals, the white reference surface is first read, and the average value of one line at that time is calculated by the average value calculation unit. Next, the difference between the average value stored in the average value storage unit and the average value of the read line is calculated by the subtraction unit, and the difference stored in the setting unit is compared by the comparison unit. The control unit determines that the light amount deterioration has not occurred, and performs shading correction using the white reference data stored in the white reference data storage unit. If the difference between the average value stored in the average value storage unit and the average value of the read line is large, the control unit determines that the light amount or the like has deteriorated and re-stores the white reference data. After that, shading correction is performed with the white reference data that is re-stored after the light amount is deteriorated. As a result, the data of the white reference surface is accumulated before the white reference surface becomes dirty, and when the light amount is deteriorated, the detection is performed and the white reference data is re-accumulated so that the white reference surface is attached. It is possible to obtain high-quality image data that is not affected by dust and dirt at all times, and that is capable of shading correction that is extremely less affected by light amount deterioration and has excellent durability.

Further, a white reference data storage unit that stores and holds one line of white reference plane image data as white reference data, and white reference data that stores the white reference plane image data in the white reference data storage unit. The detection unit that detects the maximum value and the minimum value of the shading-corrected image data, the subtraction unit that calculates the difference between the maximum value and the minimum value, the setting unit that sets the allowable value, and the difference calculated by the subtraction unit. And the comparison unit that compares the allowable value of the setting unit, and 1 if the difference exceeds the allowable value.
By including a control unit that rewrites and stores the image data of the white reference plane of the line in the white reference data storage unit, when reading a document, first, the white reference plane is read and stored in the white reference plane data storage unit. Shading correction is performed using certain white reference data and the read white reference data. Next, the maximum value and the minimum value of the data after shading correction are detected by the detection unit, and the difference is calculated by the subtraction unit. The difference and the allowable value of the setting unit are compared by the comparison unit, and when the comparison difference is small, shading correction is performed using the stored white reference data. If the difference between the maximum value and the minimum value is large, the control unit determines that dirt or the like has adhered to the white reference surface or that the light amount has deteriorated. If there is nothing wrong with scanning the original, it is determined that there is dust, dirt, etc.
Shading correction is performed using the stored white reference data. If you scan a document and the image quality is abnormal,
It is determined that the light amount and the like have deteriorated, and the white reference data of the white reference surface is stored again in the white reference data storage section. After that, shading correction is performed using the white reference data that is re-stored after the light amount deterioration. As a result, it is possible to prevent the white reference surface from being affected by dust and dirt by accumulating the image data of the white reference surface before the white reference surface becomes dirty. Especially when the amount of light locally and unevenly deteriorates,
Since the determination is performed and the white reference data is re-accumulated, shading correction that is extremely small in the influence of local light amount deterioration and the like can be performed, and high-quality image data with excellent durability can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image processing apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing the hardware arrangement of an image processing apparatus according to the first embodiment of the present invention. 1A is an image processing apparatus in the first embodiment of the present invention. 101 is an input terminal, 102 is an A / D converter, 104 is a switch, 105 is a white reference data storage unit,
Reference numeral 106 is a shading correction circuit, and 107 is an output terminal. Since these are the same as those in the conventional example, the same reference numerals are given and description thereof is omitted. The difference from the conventional example is that an average value calculation unit 2 that calculates an average value of image data of one line,
A switch 3 for switching and selecting whether to input the value of the average value output from the average value calculation unit 2 to the average value storage unit 4 or the subtraction unit 5 described later, and the value of the average value obtained from the average value calculation unit 2. The average value storage unit 4 that stores the value, the subtraction unit 5 that includes a subtractor that calculates the difference between the value stored in the average value storage unit 4 and the average value of one line that is being read, and the degree of light amount deterioration and the like. A setting unit 6 that sets a certain allowable value in advance, a comparing unit 7 including a comparator that compares the difference value obtained from the subtracting unit 5 with the allowable value stored in the setting unit 6, the switch 3, The control unit 8 that controls the switch 104, the white reference data storage unit 105, and the like is provided.

The operation of the image processing apparatus of the first embodiment of the present invention configured as above will be described below. FIG. 2 is a schematic diagram showing an average value of image data when one line of white reference data is read in the image processing apparatus of the first embodiment of the present invention. First, the white reference data read before the white reference surface becomes dirty is input from the input terminal 101, converted into a digital signal by the A / D converter 102, and then input to the white reference data storage unit 105. After that, the white reference data in the white reference data storage unit 105 is always held because it is used for shading correction. At this time, the switch 104 is switched to the A side by the control unit 8. Further, the average value calculation unit 2 detects the average value of the white reference data for one line and stores it in the average value storage unit 4. The contents of the average value storage unit 4 are always held as in the white reference data storage unit 105. here,
Since the average value storage unit 4 has a small amount of data, it may be configured by a register. At this time, the switch 3 is switched to the C side by the control unit 8. Next, when reading a document, be sure to read the white reference surface before reading the document. The read white reference data is input from the input terminal 101 to the A / D converter 1.
After being converted into a digital signal in 02, the average value of one line is calculated by the average value calculation unit 2. The switch 3 is switched to the D side by the control unit 8, and the subtraction unit 4 calculates the difference between the average value held in the average value storage unit 4 and the read average value. After that, the comparing unit 7 compares the preset allowable value of the setting unit 6 and the difference detected by the subtracting unit 5. FIG. 2 is a schematic diagram showing the image data and the average value thereof when the white reference data of one line is read. In FIG. 2, the average value A is the average value stored in the average value storage unit 4, and the average value B is the average value of the white reference data read before reading the original. When the difference between the average value A and the average value B is smaller than the allowable value of the setting unit 6, the control unit 8 determines from the comparison result of the comparison unit 7.
Determines that the light amount deterioration has not occurred, and the switch 10
Switch 4 to B side. Next, the reading of the original is started, the shading correction circuit 106 performs shading correction using the white reference data stored in the white reference data storage unit 105, and then the image data is output.
It is output from 7. When the difference between the average value A and the average value B in FIG. 2 is larger than the allowable value of the setting unit 6, the control unit 8 determines from the result of the comparison unit 7 that the light amount or the like is deteriorated, and the switch 3 is turned on. By performing the same processing as when the C side and the switch 104 are switched to the A side and the white reference data is stored in the white reference data storage unit 105 before the white reference surface becomes dirty, the average value of one line of the white reference surface and the white reference data are stored. The data is stored again in the average value storage unit 4 and the white reference data storage unit 105, respectively. Therefore, in the subsequent processing of the image data, the shading correction is performed using the deteriorated white reference data. The allowable value of the setting unit 6 is preferably set to a value that has an allowable amount that is not easily affected by dust or dirt attached to the white reference surface because the average value decreases.

The case where the average value storage unit 4 and the white reference data storage unit 105 are automatically re-stored has been described above.
When the average value decreases due to the influence of dust or dirt adhering to the white reference surface, there is no influence on the image quality, and the output image quality is abnormal and the difference of the result of the comparison unit 7 is the allowable value of the setting unit 6. After the above is confirmed by the operator, the control unit 8 may determine re-accumulation in the average value storage unit 4 or the white reference data accumulation unit 105 according to an operator's instruction. As a result, when dust or dirt is temporarily attached to the white reference surface and the average value greatly changes, it is possible to prevent the white reference data and the like from being accumulated again.

As described above, according to this embodiment, since the white reference data is written in the average value storage section before the white reference surface becomes dirty, shading correction can be performed without being affected by dust or dirt. When the light amount deteriorates, it is possible to judge the deterioration by comparing the average value of the image data and rewrite the white reference data.Therefore, shading correction that is extremely small in image quality deterioration due to the light amount deterioration can be performed. It is possible to obtain stable and high-quality images, and it is possible to extend the usage time of the light source and the like and improve the durability.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 shows the second aspect of the present invention.
3 is a block diagram illustrating a hardware configuration of an image processing apparatus according to an embodiment. FIG. 1B is an image processing apparatus in the second embodiment of the present invention. 101 is an input terminal, 102 is A
An A / D converter, a switch 104, a white reference data storage unit 105, a shading correction circuit 106, and an output terminal 107. Since these are the same as those in the conventional example, the same reference numerals are given and description thereof is omitted. The difference from the conventional example is that the maximum value detection unit 9 detects the maximum value of the image data subjected to the shading correction by the shading correction circuit 106, and the minimum value that detects the minimum value of the image data subjected to the shading correction by the shading correction circuit 106. The detection unit 10, the subtraction unit 11 for calculating the difference between the maximum value and the minimum value from the maximum value detection unit 9 and the minimum value detection unit 10, and the allowable value of the deterioration of the image data due to dust or dirt are set in advance. The setting unit 12 for setting and the comparing unit 13 for comparing the difference value obtained from the subtracting unit 11 and the allowable value stored in the setting unit 12
And when the comparison value in the comparison unit 13 exceeds the allowable value, 1
The image data of the white reference plane of the line is stored in the white reference data storage unit 1.
It is provided with a control unit 14 that is rewritten to 05 and an operation board 15 that issues an operation command to the control unit 14.

The operation of the image processing apparatus according to the second embodiment of the present invention constructed as above will be described. FIG.
FIG. 8 is a schematic diagram showing image data after image data of a white reference plane of one line is subjected to shading correction and maximum and minimum values thereof in the image processing apparatus of the second embodiment of the present invention. It is assumed that a level-corrected signal such as gain control is input to the signal photoelectrically converted by the image sensor from the input terminal 101. First, as in the first embodiment, the white reference data of the white reference surface is stored in the white reference data storage unit 105 before the white reference surface becomes dirty. next,
Scan the white reference surface before scanning the original. The image data of the white reference plane is input from the input terminal 101, converted into a digital signal by the A / D converter 102, and then shading correction is performed using the white reference data stored in the white reference data storage unit 105. Shading correction is performed in the circuit 106. After that, the maximum value of the shading-corrected data of one line is detected by the maximum value detection unit 9, the minimum value is detected by the minimum value detection unit 10, the difference is detected by the subtraction unit 11, and the difference is preset. The comparing unit 13 compares the allowable value of the setting unit 12 that is set. FIG. 4 shows an example of image data after the shading correction of the image data of the white reference plane. This time, a level-corrected signal is input from the input terminal 101. Therefore, even if the light amount deterioration occurs, it is determined that the white reference data stored in the white reference data storage unit 105 is normal and the difference between the maximum value and the minimum value is small if the white reference data is similarly deteriorated. Therefore, when the document is read, the shading correction is performed using the white reference data stored in the white reference data storage unit 105. If the difference between the maximum value and the minimum value of the data after shading correction is large, there is dust or dirt on the white reference surface being read, or local deterioration such that the light amount affects the image quality. Is determined to have occurred. If it is determined that dust or dirt is attached, the image quality is not affected. Therefore, only when the image quality is abnormal, the operator confirms the result of the comparison unit 13 on the operation board 15 to determine that the light amount is deteriorated. The determination can be made, and the control unit 14 is instructed to re-store the white reference data in the white reference data storage unit 105. The control unit 14 stores the white reference data after deterioration in the white reference data storage unit 1.
The switch 104, the white reference data storage unit 105, and the like are controlled so as to be stored in the storage unit 05. Further, it is preferable that the allowable value of the setting unit 12 is set such that the maximum value and the minimum value are less likely to be affected by noise or the like.

As described above, according to the present embodiment, the white reference data is written in the memory before the white reference surface is soiled, so that shading correction can be performed with very little influence of dust and dirt. Further, even if the output signal of the image sensor is level-corrected, it is possible to determine the local deterioration of the light amount that affects the image quality and rewrite the white reference data. Therefore, it is possible to perform shading correction that is less affected by the local deterioration of the light amount, and it is possible to improve the durability with high image quality.

[0022]

As described above, according to the present invention, the white reference data storage unit that stores and holds the image data of the white reference surface of one line and the average value calculation unit that calculates the average value of the image data of one line. And an average value storage unit that stores the average value from the average value calculation unit, and a difference between the white reference data average value of the white reference data storage unit and the image data average value of the white reference surface calculated by the average value calculation unit. And a setting unit that sets an allowable value, a comparison unit that compares the difference calculated by the subtracting unit with the allowable value of the setting unit, and if the difference exceeds the allowable value, By including the control unit that rewrites and stores the image data of the white reference plane in the white reference data storage unit, the data of the white reference plane is stored before the white reference plane becomes dirty, and when the light amount or the like deteriorates. , The white reference data is re-accumulated after making the judgment, so that Or effects of light intensity deterioration can be very small shading correction, it is possible to realize an excellent image processing apparatus in image quality and durability.

Further, a white reference data storage section that stores and holds one line of white reference plane image data as white reference data, and white reference data in which the white reference plane image data is stored in the white reference data storage section. The detection unit that detects the maximum value and the minimum value of the shading-corrected image data, the subtraction unit that calculates the difference between the maximum value and the minimum value, the setting unit that sets the allowable value, and the difference calculated by the subtraction unit. And the comparison unit that compares the allowable value of the setting unit, and 1 if the difference exceeds the allowable value.
By providing a control unit that rewrites and stores the image data of the white reference plane of the line in the white reference data storage unit, the data of the white reference plane is stored before the white reference plane becomes dirty, and the influence of dust and dirt Receive very few. In particular, when the light intensity locally or non-uniformly deteriorates, it is detected and the white reference data is re-accumulated in the white reference data accumulator, so shading correction is possible, which is minimally affected by the local light intensity deterioration. Thus, it is possible to realize an image processing device having high image quality and excellent durability.

[Brief description of drawings]

FIG. 1 is a block diagram showing a hardware configuration of an image processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram of the image processing apparatus of the first embodiment of the present invention.
A schematic diagram showing the image data and the average value when the white reference data of the line is read

FIG. 3 is a block diagram showing a hardware configuration of an image processing apparatus according to a second embodiment of the present invention.

FIG. 4 is a block diagram of an image processing apparatus according to a second embodiment of the present invention.
Schematic diagram showing image data after the image data of the white reference plane of the line is subjected to shading correction and the maximum and minimum values thereof

FIG. 5 is a schematic sectional view of an optical system of a reading unit of a conventional image processing apparatus.

FIG. 6 is a block diagram showing the configuration of a conventional image processing apparatus.

7A is a signal waveform example of image data of one line when a white reference surface is read. FIG. 7B is a signal waveform example of image data of one line when a white original is read. ) And (b), the signal waveform example of the image data after shading correction by both image data

FIG. 8A is a signal waveform example of image data of one line when a white reference surface with dust or dirt is read. FIG. 8B is a signal waveform example of image data of one line when a white document is read. (C) Example of signal waveform of image data after shading correction by both image data of FIGS. 8 (a) and 8 (b)

FIG. 9A is a signal waveform example of image data of one line when a white reference surface is read. FIG. 9B is a signal waveform example of image data of one line when a white document is read after deterioration of light amount. Signal waveform of image data after shading correction by both image data of FIGS. 9A and 9B

[Explanation of symbols]

 1A Image processing apparatus in the first embodiment of the present invention 1B Image processing apparatus in the second embodiment of the present invention 2 Average value calculation unit 3 Switch 4 Average value storage unit 5,11 Subtraction unit 6,12 Setting unit 7,13 Comparison Sections 8 and 14 Control section 9 Maximum value detection section 10 Minimum value detection section 15 Operation board 101 Input terminal 102 A / D converter 103 Control section 104 Switch 105 White reference data storage section 106 Shading correction circuit 107 Output terminal 301 White reference surface 302 glass 303 light source 304 mirror 305 lens 306 image sensor 307 original

Claims (2)

[Claims] 1. An image processing apparatus having a white reference surface of one line and sequentially reading image data line by line to perform shading correction, and storing and holding the image data of the white reference surface of one line. A white reference data storage unit, an average value calculation unit that calculates an average value of the image data for one line, an average value storage unit that stores the average value from the average value calculation unit, and an average value calculation unit. The subtraction unit that calculates the difference between the white reference data average value of the white reference data storage unit and the image data average value of the white reference surface calculated by the above, the setting unit that sets the allowable value, and the subtraction unit A comparing unit for comparing the difference obtained with the allowable value of the setting unit; and, if the difference exceeds the allowable value, the white reference data accumulating unit stores the image data of the white reference plane of one line. And a control unit that rewrites The image processing apparatus characterized by comprising. 2. An image processing apparatus having a white reference surface of one line and sequentially reading image data for each line to perform shading correction, wherein the image data of the white reference surface of one line is used as white reference data. A white reference data storage unit that stores and holds, and detects the maximum value and the minimum value of image data whose image data on the white reference surface is shading-corrected by the white reference data held in the white reference data storage unit. A detection unit, a subtraction unit that calculates a difference between the maximum value and the minimum value, a setting unit that sets an allowable value, and a comparison between the difference calculated by the subtraction unit and the allowable value of the setting unit. And a control unit that rewrites the image data of one line of the white reference surface to the white reference data storage unit when the difference exceeds the allowable value. You Image processing apparatus.