JP2859988B2 - Scanned image correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a read image correcting apparatus applied to a copying machine having a CCD.

[0002]

2. Description of the Related Art In a copying machine having a CCD, a read image
Then, two corrections are made.

[0003] One of them is a dark component correction, in which no light is incident on the CCD when reading the black level.
The low level output from the CCD depends on the characteristics of the CCD element, and this is corrected. The other is shading correction, which is caused by variations in the characteristics of the lens and the sensitivity of each element of the CCD, etc., despite the fact that uniform light is incident on the CCD when reading the white level. Since the output does not reach a constant level but drops from the center to both ends, this is corrected.

FIG. 3 is a diagram of each waveform when reading by a CCD. FIG. 3A shows an original waveform of an image at the time of image reading, and FIG. 3B shows a waveform of a dark component.
(C) is a waveform after dark component correction obtained by subtracting a dark component waveform (FIG. 3 (B)) from the original waveform (FIG. 3 (A)) of the image, and FIG. 3 (D) is a shading waveform. , FIG.
(E) shows a waveform which is completely corrected by multiplying the waveform after dark component correction (FIG. 3 (C)) by the shading correction waveform (FIG. 3 (D)).

[0005] Figure 4 is suitable for a copying machine having a conventional CCD
FIG. 2 is a configuration diagram of a read image correction device that has been used .

The procedure of the correction is performed as follows.

[0007] First, in a state in which no light is incident on the CCD without lighting the optical system of the light source of the copying machine, the dark component D _d is a CCD output at that time as a dark component correction data is written into the dark component correction memory 62 . Next, move the optical system to the position of the reference white plate, by turning on the light source, CC at this time
255 / based on the shading component D _s which is the D output
The D _s written in Shading <br/> ring correction memory 63 as shading component correction data. As described above, after writing to both correction memories is completed, the optical system is scanned to read an image, and the original waveform of the A / D output from 61 (FIG. 3)
The waveform (FIG. 3B) written to the dark component correction memory 62 from FIG. 3A is subtracted by 64 to obtain the waveform shown in FIG. Further, the waveform of FIG. 3C is multiplied by the waveform (FIG. 3D) written in the shading correction memory 63 by 65 to obtain a completely corrected waveform of FIG. 3E.

When the above correction is expressed by a correction equation, dark component correction
Data is D _d , shading correction data is 255 / D
_s , the read image data is D, and the corrected image data
= A _{(D-D d) × 255} / D s.

[0009]

The conventional correction method as described above requires two memories for CCD correction.
In addition to the complicated structure, the memory has the highest cost in terms of the circuit structure, leading to an increase in cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a read image correcting apparatus which realizes a function consolidation by reducing a costly memory in a circuit configuration and is applied to a copying machine having an inexpensive CCD.

[0011]

Means for Solving the Problems The invention described in claim 1
Is read by a CCD sensor consisting of multiple CCD elements.
Component correction and shading correction
In the image correction apparatus reading for performing positive, One to each CCD element
The reflected light from the light source reflected by the reference white plate
Shading component D _s KaraMotome an output value when you are
Shading component correction data and light
The shell and the dark component D _d is the output value when not
Dark component correction data
A single correction memory for writing data, and
Data D and the shading component correction data
Multiplication circuit for performing the shading correction by
If, subtract the dark component correction data from the output of the multiplier circuit
A subtraction circuit for performing the dark component correction by
I have. Further, the invention described in claim 2 provides a plurality of C
Original images read by a CCD sensor composed of CD elements
For dark component correction and shading correction
In the image correction device, the reference white
When the reflected light from the light source reflected by the color plate is incident
Shede obtained from the shading component D _s is the force value
Component correction data and no light incident
The output value of the dark component _Dd and the shading component
Write the dark component correction data obtained from the minute correction data
A single correction memory, and one address of the correction memory
The above two for one CCD element
Correction data is written.

According to the first aspect of the present invention, the dark component correction used in the dark component correction process and the shading correction process is performed.
Single memory for positive data and shading correction data
, The manufacturing cost is reduced.
Also, shading correction for scanned original images
The processing is performed by the multiplication circuit, and the dark component correction
The processing is performed by a subtraction circuit.
Was. Therefore, the circuit configuration is not complicated, and these corrections
Processing can be executed at high speed. For scanned images
The correction is performed in the following procedure. Note that each CCD element
And the dark component D _d , the shading component D _s , and the read image
Let it be data D. In the upper (or lower) of the correction memory, the shade
Writes 255 / D _s as ring correction data. Dark component correction in the lower (or upper) of the correction memory
The shading correction data 255 /
Write D _d × 255 / D _s obtained by multiplying D _s and dark component D _d
Get in. It is written in the correction memory and the read image data D Tei
Multiplying the shading component correction data 255 / D _s that
( D × 255 / D _s ) . Dark component correction from D × 255 / D _s resulting from this multiplication
The data D _d × 255 / D _s is subtracted. In other words, the corrected image data _{= D × 255 / D s -D} d × 255 / D s = (D-D d) × 255 / D s. That is, a single complement is applied to the read image data D.
Dark component correction processing and shading correction processing
Can do so. The invention described in claim 2
Corresponds to one CCD element at one address of the memory.
Dark component correction data and shading correction data
Since it is written, dark component correction processing and system
When executing the edging correction process, the corresponding
Reading of both correction data can be performed simultaneously.
(It can be done with one address specification.)

FIG. 2 is a block diagram showing a read image compensator according to an embodiment of the present invention.
FIG. 1 is a schematic configuration diagram of a color copying machine to which a normal device is applied .

An original table 81 made of hard transparent glass is provided on the upper surface of the main body 80 of the color copying machine.
Below the document table 81, a lamp unit 1, mirrors 2, 3, and 4 for guiding reflected light of the document to a lens unit 5, a CCD sensor 6, and the like are provided. Below that is a CCD
A laser driver unit 7 to which data captured by the sensor 6 is sent and mirrors 8 and 9 are provided. The laser light emitted from the laser driver unit 7 is applied to the photosensitive drum 1 disposed slightly upper right from the center of the main body 80.
Irradiated on zero.

The photosensitive drum 10 is rotatable in the direction of arrow a.
0, a charging charger 16 for uniformly charging the surface, a black developing tank 11, a yellow developing tank 12, and a magenta developing tank 1.
3. Developing device provided with cyan developing tank 14, transfer belt 1
7, a cleaning unit 21, a static elimination lamp 15, and the like. Black developing tank 11, yellow developing tank 12,
Corresponding toners are stored in the magenta developing tank 13 and the cyan developing tank 14, respectively. The paper feed unit 20 is provided at the lower right of the main body 80, and the fixing unit 31 and the discharge roller 32 are further provided at the lower left of the main body 80.

With the above configuration, the three- color copying operation is performed as follows.

When a print switch (not shown) is depressed and the surface of the photosensitive drum 10 is uniformly charged by the charging charger 16, a document (not shown) placed on the document table 81 in the first scan. Is irradiated by the lamp unit 1, and reflected light from the original is guided to the light receiving surface of the CCD sensor 6 via the mirrors 2, 3, 4 and the lens unit 5 and is taken in as an electric signal. The image data captured by the CCD sensor 6 generates yellow data through an image processing unit (not shown), is sent to a laser driver unit 7, is output as laser light, and is output via mirrors 8 and 9 to a photosensitive drum 10. A yellow electrostatic latent image is formed by irradiating the upper surface. Yellow toner is supplied from the yellow developing tank 12 to the electrostatic latent image in the image area to form a yellow toner image. As the photoconductor drum 10 rotates in the direction of arrow a, the yellow toner image also moves around and is transferred to the transfer belt 17 which is partially pressed against the photoconductor drum 10. At this time, toner that does not contribute to the transfer remains on the surface of the photosensitive drum 10, and the cleaning unit 21 scrapes off the residual toner. Then, the charge removing lamp 15 removes the charge remaining on the surface of the photosensitive drum 10.

When the above steps are completed , the charger 16 uniformly charges the surface of the photosensitive drum 10 again, and
The document data obtained by the second scanning passes through the image processing unit, and the photosensitive drum 10 is exposed to laser light to form a magenta electrostatic latent image. Magenta toner is supplied from the magenta developing tank 13 to the electrostatic latent image in the image area to form a magenta toner image. When the photosensitive drum 10 rotates in the direction of the arrow a, the magenta toner image also moves around and is transferred to the transfer belt 17 to perform image superposition. Then, the cleaning unit 21 scrapes off the residual toner on the surface of the photoconductor drum 10, and the residual charge is removed by the discharging lamp 15. Similarly, the same operation is performed on the cyan data, and the cyan toner image is transferred onto the transfer belt 17 to perform the final image superposition. Thereafter, the transfer belt 17 on which the image is superimposed is provided.
The upper toner image is transferred onto copy paper conveyed from the paper supply unit 20, passes through a fixing unit 31, and is discharged by a discharge roller 32.

In the four-color copying process, black processing is added to the above-described process. On the other hand, in black-and-white copying, black toner is supplied from the black developing tank 11 to the electrostatic latent image on the photosensitive drum 10, and this toner image is transferred. The transfer is performed by transferring the image onto copy paper via the transfer belt 17.

As described above, in this color copying machine, the CCD sensor 6 takes in the information of the original and processes it.
Due to variations in the characteristics and sensitivity of the CCD element, there is a low level output even though there is no light incident, or the output does not reach a certain level even if uniform light is incident. It is necessary to correct these because the level drops from to the both ends.

FIG. 1 shows a read image according to an embodiment of the present invention .
FIG. 3 is a diagram illustrating a configuration of a correction device . First, in order to perform shading correction, when is lit by allowed and the light source moves to the position of the reference white plate an optical system (not shown) [CCD output: shading component D _s ] Based on shading correction
The data is written into the correction memory 54. Specifically, the conversion of 255 / D _s is performed through the ROM table 52 ,
The data is written into the upper (or lower) of the correction memory 54 as shading correction data . Next, the dark component D _d D _d × 25 where the by multiplying the shading correction data 53
5 / D _s as dark component correction data .
Write to the word (or upper) . To this end, the optical system (not shown) is moved to move the optical system at the position of the reference black plate [CCD output: dark component D _d ] Is measured. The same CCD element
Correction data and dark component correction data in
Is written to the same address. Therefore, the same
Correction data for the CCD element of
The reading of the dark component correction data can be performed by one address specification.
I can do it. After writing the correction memory in this manner, the optical system is scanned to read an image , and the read image data is read.
Shading correction data written in the correction memory 54 (A / D output from 51) over data D (255 / D
_s) and were multiplied by 55, further dark component correction data D _d × 255 / D _s written in the correction memory 54 5
The result of the multiplication of 5 is subtracted by 56. As a result, the image data D read by one correction memory 54 is
A correction of (D−D _d ) × 255 / D _s can be performed.

When an 8-bit correction memory is used as the accuracy of the correction memory, it is desirable to use a dark component of 3 bits and a shading of 5 bits by giving weight to the dark component and shading.

[0021]

As it is evident from the foregoing description, according to the present invention, KuraNaru
For both minute correction processing and shading correction processing
Dark component correction data and shading component correction data to be used
Data to a single memory. Also read
Subtract for dark component correction processing on the taken original image
Circuit to perform shading correction processing.
Circuit is executed by a multiplication circuit.
The configuration is not complicated, and these correction processes can be executed at high speed.
Can be In addition, expensive correction memories are reduced from two to one.
It was able to reduce the cost while maintaining the functions.

Further, one address is stored in one address of the memory.
Dark component correction data and shade for CCD elements
Correction data is written so that the dark component
When performing correction processing and shading correction processing
At the same time, read out both corresponding correction data from the memory simultaneously.
(Can be done with one address specification)
You. ).

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a read image correcting apparatus according to an embodiment of the present invention.
It is a diagram showing a formation.

FIG. 2 is a block diagram showing a read image correction apparatus according to an embodiment of the present invention;
1 is a schematic configuration diagram of a color copying machine used.

FIG. 3 is a diagram of each waveform at the time of reading by a CCD.

FIG. 4 is a diagram illustrating a configuration of a conventional read image correction device .

[Description of Reference Numerals] 6 CCD sensor 54 correction memory D _d dark component D _s shea Edingu component D read data

Claims (2)

(57) [Claims] 1. A CCD sensor comprising a plurality of CCD elements.
Dark component correction and shading
In the reading image correction device that performs the reading correction, for each CCD element, the opposite of the light source reflected by the reference white plate
Shadin which is the output value when the light is incident
Shading component correction data obtained from the grayed components D _s,
And the output value when no light is incident
Min _Dd and the shading component correction data.
A single correction memory for writing the corrected dark component correction data, the read image data D and the shading component correction.
Multiplying the data by data
A multiplication circuit for performing a positive operation, and subtracting dark component correction data from an output of the multiplication circuit.
And a subtraction circuit for performing the dark component correction by
Read image correction device. 2. A CCD sensor comprising a plurality of CCD elements.
Dark component correction and shading
In the reading image correction device that performs the reading correction, for each CCD element, the opposite of the light source reflected by the reference white plate
Shadin which is the output value when the light is incident
Shading component correction data obtained from the grayed components D _s,
And the output value when no light is incident
Min _Dd and the shading component correction data.
A single correction memory to write the dark component correction data
For one address of the correction memory, one CC
The above two correction data for the D element are written
Read image correction device.