JP2001346012A - Image reader and adjusting method of image signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a difference in levels of signals as a defect of a linear image sensor in a left and right separate reading system. SOLUTION: This image reader is provided with the linear image sensor (208) to output image signals of each area divided into plural ones of a light receiving pixel string from separate output terminals, plural signal processing means (1 to 8) to perform prescribed signal processings to the outputted image signals, a reference white board (210), a reference density member (701) having prescribed density of halftone, an adjustment data acquiring means (20) to make the levels of the image signals when the reference white board is read approximately coincide with the first prescribed level, to make the levels of the image signals when the reference density member is read approximately coincide with the second prescribed level and to adjust the levels of the image signals corresponding to density except the ones of reference white board and the reference density member to the level to be obtained by interpolating the first and second prescribed levels and adjusting means (13 to 16) to adjust the image signals by using the adjustment data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus using a linear image sensor having a left / right separated reading structure, and more particularly to an image reading apparatus having a joint correction function.

[0002]

2. Description of the Related Art Conventionally, there is an image reading apparatus using a linear image sensor.

FIG. 12 is a diagram showing a configuration of a linear CCD image sensor used in a conventional image reading apparatus.

In FIG. 12, reference numeral 101 denotes a light receiving pixel row of a linear CCD image sensor, and 102 and 103 separate electric charges accumulated in each pixel of the light receiving pixel row into odd (ODD) pixels and even (EVEN) pixels. Analog shift registers for reading in order, 104 and 105
Is an output amplifier for converting charges read from the analog shift registers 102 and 103 into voltage signals and outputting the voltage signals.

FIG. 13 shows an example of the configuration of an image reading apparatus using the above-described linear CCD image sensor.

Referring to FIG. 13, reference numeral 201 denotes a platen glass;
202 is a document, 203 is an illumination lamp for illuminating the document, 204 to 206 are first, second, and third mirrors, respectively, 207 is a lens for forming a document image on the light receiving surface of the linear image sensor 208, Reference numeral 209 denotes an image sensor driving circuit for driving the linear image sensor 208, and reference numeral 210 denotes a white plate for reading as a reference for shading correction processing.

The illumination lamp 203 and the first to third mirrors 2
Reference numerals 04 to 206 are at positions indicated by solid lines during normal document reading, but move to positions indicated by dotted lines when reading the white plate 210. When reading the original, the mirror can be two-dimensionally read by moving each mirror in the sub-scanning direction S.

In the linear CCD image sensor shown in FIG. 12, the charge stored in each pixel of the light receiving pixel row 101 is read out separately for ODD and EVEN because of the transfer speed of the analog shift registers 102 and 103. This is necessary to achieve a reading speed higher than a predetermined speed.

However, in recent years, there has been an increasing demand for an image reading apparatus having a higher reading speed than before, and it is necessary to realize a reading speed which cannot be achieved by a linear CCD image sensor of the ODD / EVEN separation reading type as shown in FIG. Have been.

Under such circumstances, as shown in FIG. 14, an ODD / EVEN linear CCD image sensor capable of realizing a reading speed twice as high as that of an ODD / EVEN separation reading type linear CCD image sensor is shown.
In addition to the above-described separation readout, a linear CCD image sensor having a structure in which charges in a light receiving pixel column are read out by dividing into left and right sides has been proposed.

In FIG. 14, reference numeral 301 denotes a light receiving pixel row of a linear CCD image sensor, and 302 to 305 separate electric charges accumulated in each pixel of the light receiving pixel row into odd (ODD) pixels and even (EVEN) pixels. Analog shift registers for sequentially reading in different directions, 306 to
An output amplifier 309 converts the charges read from the analog shift registers 302 to 305 into voltage signals and outputs the voltage signals.

The analog shift registers 302 to 305 of the linear CCD image sensor shown in FIG. 14 divide the electric charge accumulated in each pixel of the light receiving pixel column 301 into two parts at the center, and separate them into ODD / EVEN. And read.

FIG. 15 shows the driving signals and C signals of the CCD image sensor having the left-right divided reading structure shown in FIG.
4 shows a timing chart of an output signal from a CD image sensor.

In FIG. 15, "SH" is a charge shift pulse, and controls a gate for simultaneously shifting charges accumulated in the light receiving pixel column 301 to the analog shift registers 302 to 305. Therefore, as shown in FIG. 15, the time between the SH pulse and the next SH pulse is an accumulation time (Tint) for accumulating charges in the light receiving unit.

In FIG. 15, .phi.1 and .phi.2 are charge transfer pulses for driving the analog shift registers 302 to 305, which are simultaneously shifted from the light receiving section to the analog shift registers 302 to 305 by SH pulses. The charge is transferred to each of the analog shift registers 302 to
The pixel is sequentially moved by one pixel in the direction of the output amplifiers 306 to 309 at the end of the pixel 305. As a result, ODD-
1, image signals such as EVEN-1, ODD-2, and EVEN-2 are output.

[0016]

However, FIG.
When the linear CCD image sensor of the left-right division reading method shown in (1) is used, a level difference occurs between the left and right reading signals due to a slight difference in linearity of each of the output signals of a total of four channels. In addition, a read signal level step occurs on the left and right.

If only ODD / EVEN divisional reading is performed as in a conventional linear CCD image sensor, O
Even if a signal level difference occurs in DD / EVEN, only a very fine repetitive pattern is slightly added to the image on the image. However, if a level difference occurs in the read signal level between the left and right division positions, Even a small signal step is very noticeable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to eliminate a signal step which is a disadvantage of a linear image sensor of a left-right divided reading system.

[0019]

According to a preferred embodiment of the present invention, there is provided an image reading apparatus comprising:
A linear image sensor that outputs an image signal of each region divided into a plurality of light receiving pixel columns from separate output terminals corresponding to each region, and performs predetermined signal processing on the image signal output from each of the output terminals; A plurality of signal processing means provided corresponding to each area, a reference white plate, a reference density member having a predetermined halftone density, and a plurality of signal processing means when reading the reference white plate. Making the level of the output image signal substantially equal to the first predetermined level;
When the reference density member is read, the levels of the image signals output from the plurality of signal processing units are made substantially equal to a second predetermined level, and the levels correspond to other than the densities of the reference white plate and the reference density member. The level of the image signal
And adjustment data obtaining means for obtaining, for each of the plurality of signal processing means, adjustment data for adjusting to a level obtained by interpolating between a second predetermined level and the plurality of signal processing means using the adjustment data. Adjusting means for adjusting the image signal output from the means.

According to a preferred aspect of the present invention, an image reading apparatus includes: a document table on which a document to be read is placed; and an image signal of each of a plurality of divided light receiving pixel rows. A linear image sensor for reading from separate output terminals corresponding to each of the plurality of image processing units; a plurality of signal processing means provided for each region for performing predetermined signal processing on an image signal output from each of the output terminals; Plate, a control means for controlling the linear image sensor to read the reference density member when a reference density member having a predetermined density of halftone is placed on the platen; and When reading, the levels of the image signals output from the plurality of signal processing means are made substantially equal to a first predetermined level, and when the reference density member is read,
The levels of the image signals output from the plurality of signal processing units are made substantially equal to a second predetermined level, and the levels of the image signals corresponding to other than the densities of the reference white plate and the reference density member are set to the first and second levels. An adjustment data acquisition unit that obtains, for each of the plurality of signal processing units, adjustment data that adjusts to a level obtained by interpolating between two predetermined levels; Adjusting means for adjusting the output image signal.

According to a preferred aspect of the present invention, there is provided a linear image sensor for outputting an image signal of each of a plurality of divided regions of a light receiving pixel column from separate output terminals corresponding to each of the regions. A plurality of signal processing means for performing predetermined signal processing on an image signal output from each terminal, provided for each region, a reference white plate, and a reference density member having a predetermined density of halftone. An image signal adjusting method in the image reading device includes: a first reading step of reading the reference white plate by the linear image sensor, performing signal processing by the plurality of signal processing units, and outputting an image signal; A second reading step of reading the reference density member, and performing image processing by the plurality of signal processing units to output an image signal;
On the basis of the image signals obtained in the first and second reading steps, the level of the image signal output in the first reading step is made substantially equal to a first predetermined level, and in the second reading step, The level of the output image signal is made to substantially match the second predetermined level, and the level of the image signal corresponding to a density other than the density of the reference white plate and the reference density member is interpolated between the first and second predetermined levels. An adjustment data obtaining step of respectively obtaining adjustment data to be adjusted to a level obtained by each of the plurality of signal processing means, and adjusting image signals output from the corresponding plurality of signal processing means using the adjustment data. Adjusting step.

According to another preferred embodiment of the present invention, a document table on which a document to be read is placed, and an image signal of each of a plurality of divided light receiving pixel rows are assigned to each area. A linear image sensor for reading from separate output terminals, a plurality of signal processing means provided for each region for performing predetermined signal processing on the image signal output from each of the output terminals, and a reference white plate. A method of adjusting an image signal in the image reading apparatus having the first reading step of reading the reference white plate by the linear image sensor, performing signal processing by the plurality of signal processing units and outputting an image signal; The linear image sensor reads the reference density member having a predetermined halftone density placed on the image sensor, and performs signal processing by the plurality of signal processing units to form an image signal. A second reading step of outputting,
On the basis of the image signals obtained in the first and second reading steps, the level of the image signal output in the first reading step is made substantially equal to a first predetermined level, and in the second reading step, The level of the output image signal is made to substantially match the second predetermined level, and the level of the image signal corresponding to a density other than the density of the reference white plate and the reference density member is interpolated between the first and second predetermined levels. An adjustment data obtaining step of respectively obtaining adjustment data to be adjusted to a level obtained by each of the plurality of signal processing means, and adjusting image signals output from the corresponding plurality of signal processing means using the adjustment data. Adjusting step.

Preferably, at least one of the first and second predetermined levels is set in advance.

Alternatively, the first predetermined level is an average value of signal levels obtained from the plurality of signal processing means when the reference white plate is read, and the method of adjusting the image signal is as follows. Determining the average level of the signal levels obtained from the plurality of signal processing means in the first reading step.

Alternatively, the first predetermined level is a maximum value of a signal level obtained from the plurality of signal processing means when the reference white plate is read, and the method of adjusting the image signal is the first level. Determining a maximum value of signal levels obtained from the plurality of signal processing means in the first reading step.

Alternatively, the first predetermined level is a minimum value of a signal level obtained from the plurality of signal processing units when the reference white plate is read, and the method of adjusting the image signal includes the first level. And determining a minimum value of signal levels obtained from the plurality of signal processing means in the first reading step.

Preferably, the second predetermined level is an average value of signal levels obtained from the plurality of signal processing means when reading the reference density member. The method further includes a step of obtaining, as the second predetermined level, an average value of signal levels obtained from the plurality of signal processing units in the second reading step.

Alternatively, the second predetermined level is a maximum value of a signal level obtained from the plurality of signal processing means when the reference density member is read. The predetermined level of the second
The step of obtaining the maximum value of the signal levels obtained from the plurality of signal processing means in the reading step.

Alternatively, the second predetermined level is a minimum value of a signal level obtained from the plurality of signal processing means when reading the reference density member. The predetermined level of the second
The step of obtaining the minimum value of the signal level obtained from the plurality of signal processing means in the reading step.

Alternatively, the first predetermined level is a maximum value of signal levels obtained from the plurality of signal processing means when the reference white plate is read, and the second predetermined level is the reference density. The method of adjusting the image signal is the minimum value of the signal levels obtained from the plurality of signal processing units when the member is read, and the first reading step d is performed as the first predetermined level. A step of obtaining a maximum value of a signal level obtained from the signal processing means and obtaining a minimum value of the signal levels obtained from the plurality of signal processing means in the second reading step as the second predetermined level.

[0031] Preferably, the adjustment data obtaining means includes:
Each of the maximum levels of the image signals obtained from the plurality of signal processing means obtains adjustment data so as to be the adjusted maximum level, and in the adjustment data obtaining step, the image data obtained from the plurality of signal processing means is obtained. Adjustment data is obtained such that each of the maximum levels becomes the adjusted maximum level.

Preferably, said interpolation is linear interpolation based on said first and second predetermined levels.

Alternatively, the interpolation is a curve interpolation based on the first and second predetermined levels.

Alternatively, the interpolation is performed by calculation.

Preferably, the adjustment data is an LUT.

Preferably, the linear image sensor has a left-right separated reading structure.

Preferably, each of the plurality of signal processing means includes an amplifying means for amplifying a signal output from the output terminal.

[0038] Preferably, each of the plurality of signal processing means includes A / D conversion means for converting a signal output from the output terminal from an analog signal to a digital signal.

According to a preferred aspect of the present invention, the image reading device is connected to a printing device, the reference density member is printed by the printing device, and the method of adjusting an image signal is performed by using the reference density member. The method further includes the step of printing with the printing device.

Preferably, the reference density member has at least one or more uniform density pattern portions.

According to a preferred aspect of the present invention, the printing apparatus is integrally formed with the printing apparatus.

[0042]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

<First Embodiment> FIGS. 1, 2 and 3
1 shows a configuration of the image reading device according to the first embodiment of the present invention. In FIG. 1, reference numerals 1 to 4 denote amplifiers for amplifying output signals from the linear CCD image sensor having the left-right divided readout structure shown in FIG.
A / D conversion circuits for converting an output signal from the D image sensor into a digital signal; 9 to 12, black offset correction processing for subtracting the black offset of the image signal of each channel, and black offset for performing shading correction -It is a shading correction circuit.

LUTs (LOOK UP TABLE) 13 to 16 correct the linearity of each channel by table conversion, and correct the connection of left and right read signals (correction of signal steps).
It is for realizing.

The first memory 17 temporarily stores the output signal from the linear CCD image sensor output at the timing shown in FIG. 15, and realizes the pixel rearrangement for rearranging and outputting the correct pixel order. Of
The second memory 19 stores the section signal (PHEN) shown in FIG.
Is a memory circuit for temporarily storing the pixel data in the “H” section of FIG. CP
U20 reads the image data from the second memory 19,
By adding and averaging the pixel data in the vicinity of the connection position, a reading level at the connection position of each channel can be obtained.

FIG. 2 shows an image reading apparatus 10 according to the present invention.
0 is shown.

The image reading apparatus 100 shown in FIG.
3 in that it has a gray reference plate 701.

In FIG. 2, reference numeral 201 denotes a document table glass; 202, a document; 203, an illumination lamp for illuminating the document; 204 to 206, first, second, and third mirrors; Image sensor 208
209, an image sensor driving circuit for driving the linear image sensor 208; and 210, a white plate for reading as a reference for shading correction processing.

Illumination lamp 203 and first to third mirrors 2
Reference numerals 04 to 206 are at positions indicated by solid lines during normal document reading, but move to positions indicated by dotted lines when reading the white plate 210 and the gray reference plate 701. Also,
When reading a document, the mirror can be read two-dimensionally by moving each mirror in the sub-scanning direction S.

The gray reference plate 701 is a gray (gray between white and black) plate. In FIG. 2, the gray reference plate 7
FIG. 3 shows an example in which the white part and the gray part are arranged side by side with the white plate 210 for shading correction. However, the present invention is not limited to this arrangement, and the white part and the gray part are formed on the same plate as shown in FIG. You may do so.

Next, a method for correcting the linearity of each channel according to the first embodiment of the present invention will be described in detail.

FIG. 4A shows an example of the relationship between the signal levels of the respective channels before performing the linearity correction processing (before LUT conversion). In FIG. 4A, the horizontal axis represents the brightness of the document, and the vertical axis represents the read image signal level. The black level of each channel is black-offset corrected by the black offset / shading correction circuits 9 to 12, and the white level is corrected by shading correction. The reading level of each channel varies. This is because an amplifier and an AD conversion circuit through which an output signal from each channel passes are different from each other, so that a slight difference in linearity characteristic is inevitably generated.

As shown in FIG. 4B, the role of the LUTs 13 to 16 is to make the signal levels of the respective channels coincide with each other for the same brightness by correcting and converting the signal levels of the respective channels to a predetermined linearity. It is.

In order to realize the linearity correction based on the above idea, according to the present invention, for each of the white plate 210 and the gray reference plate 701 shown in FIG. 2, the average value of the read level of the pixel near the connection position is provided for each channel. Get. This is because, as described above, the image data obtained by reading the white plate 210 and the gray reference plate 701 are temporarily stored in the second memory 19, read by the CPU 20, and connected for each image data for each channel. This can be realized by averaging pixel data near the position.

The CPU 20 creates a linearity correction table as shown in FIG. 5 for each channel from the average value of the pixels near the connection position between the white plate 210 and the gray reference plate 701 and sets them in the LUTs 13 to 16.

FIGS. 5A and 5B are graphs showing an example of the linearity conversion characteristics of the LUT in the case of 10-bit image data. The horizontal axis represents the input signal level to the LUT, and the vertical axis represents the output from the LUT. The signal level is shown. FIG.
(A) and (b) show that the average value of the gray reference plate reading level before LUT correction is used as the reference level G of the gray reference plate.
(Hereinafter, referred to as “gray reference level”) and LU
This is an LUT content having a characteristic of converting a white plate reading level average value before T correction into a white plate reference level W (hereinafter, referred to as a “white reference level”).

By calculating the LUT contents as shown in FIG. 5 for each channel and setting the LUTs in the LUTs 13 to 16, the linearity of each channel can be corrected to the same characteristic.

FIG. 5A is a graph obtained by interpolating the contents of the conversion table for the LUT input other than the read level of the gray reference plate 701 and the white plate 210 with two straight lines, and FIG. This is interpolated with a curve. When performing interpolation using a curve, approximate interpolation can be performed using various arithmetic functions such as an exponential function and an n-th order function.

Here, the white reference level W and the gray reference level G will be described. Here, two methods for setting the white reference level W and the gray reference level G will be described.

The first method is a method in which a white reference level W and a gray reference level G are determined in advance. For example, the white reference level W is set in advance to an ideal reading level of the white plate 210, that is, a value such as what value the reading device should read the white plate 210. This is a value for the design specification of the reader. The same applies to the gray reference level G. In this case, the white reference level W and the gray reference level G are each handled as a predetermined fixed value.

On the other hand, the second method is a method of calculating from the read level of each channel. For example, the read level of each channel of the white plate 210 and the gray reference plate 701 is

(Channel) (White reference plate reading level) (Gray reference plate reading level) ODD-1 W1 G1

ODD-2 W2 G2

EVEN-1 W3 G3

EVEN-2 W4 G4

In this case, a white reference level W is obtained by the following methods (1) to (3), and a gray reference level G is obtained by the following methods (4) to (6). (1) W = Average of W1 to W4

(2) W = maximum value of W1 to W4

(3) W = minimum value of W1 to W4

(4) G = Average of G1 to G4

(5) G = maximum value of G1 to G4

(6) G = minimum value of G1 to G4

Note that a calculation method other than the above may be used.

This allows a certain degree of variation in the virtual reference characteristic to be corrected in order to match the linearity of each channel at the connection position. As the original characteristic, the difference in the linearity of each channel shown in FIG. 4A is a very small amount. Therefore, even if the reference characteristic fluctuates within the range of the variation as described above, almost no problem occurs. Often not.

However, in this case, if the LUTs 13 to 16 are set so that the maximum level (saturation level) of the signal after LUT conversion becomes smaller than the maximum level (saturation level) of the signal before LUT conversion, FIG. As shown by “Δ” in No. 6, there is a possibility that a white level difference occurs between channels in the LUT output stage.

Specifically, in the case of FIG.
The LUT output of channel A, which is any one of DD-2, EVEN-1, and EVEN-2, has a maximum of "10".
23 ", but the maximum value of the LUT output of the B channel different from the A channel is smaller than" 1023 ". In this state, if a white document where the signal is saturated is read, it is apparent that Then, a white level difference occurs between the A channel and the B channel.

Therefore, at the time of LUT conversion, LU
It is necessary to set the contents of the LUTs 13 to 16 so that the maximum level (saturation level) of the signal after T conversion does not become smaller than the maximum level (saturation level) of the signal before LUT conversion.

To set the LUTs 13 to 16 as described above, for example, the following may be performed.

Countermeasure (1) The method of calculating the white reference level W and the gray reference level G is as follows. That is, W = the maximum value of W1 to W4 G = the minimum value of G1 to G4 The intermediate value is obtained by linear interpolation.

In this combination, the slope of the straight line between the LUT and the WG becomes 1 or more, so that the maximum level (saturation level) of the signal after LUT conversion is larger than the maximum level (saturation level) of the signal before LUT conversion. It never gets smaller.

Countermeasure (2) As shown in FIG. 7, the LUT table is set so that the maximum input level of the LUT always matches the maximum output level.

<Second Embodiment> Next, a second embodiment of the present invention will be described.

In the first embodiment, a gray reference plate 701 is required in addition to the white plate 210 for shading correction in calculating the LUT contents of the linearity correction, so that the cost and size of the image reading apparatus are increased. There was a problem. To avoid this, the image reading apparatus 100 ′ according to the second embodiment does not have the gray reference plate 701 as shown in FIG. 8, but instead places the reference chart 113 having a uniform density on the platen glass. Using this, the contents of the LUT are calculated. In this case, the image reading apparatus reads the reference chart and the white plate 210 by the instruction means (not shown) and calculates the contents of the LUT.

In this case, as the reference chart 113 to be used, one kind of uniform density pattern as shown in FIG. 9A or a step gradation (a plurality of uniform density patterns) as shown in FIG. And so on. In particular, FIG.
In the case of, since different densities can be read, FIG.
As shown in (1), many reference points that can be used for calculating the LUT content can be obtained. Therefore, a more accurate correction LUT can be calculated. In this case, the white reference level W and the gray reference levels (here, G1 to G4) corresponding to the gradations of the reference chart can be set in the same manner as in the first embodiment.

In the above, the reference chart can be used, for example, as a printout of image data created by a personal computer or the like. However, in this case, it is necessary to optically blur the black DOT printed on the print output to obtain a uniform density, so that the reference chart is not directly placed on the platen glass, but is slightly lifted to support it. Sometimes it is better to use equipment. Instead of the auxiliary device, another method such as placing another glass plate on the platen glass may be used.

Further, as shown in FIG. 11, when an image reading apparatus 110 'according to the present invention is used as a copying machine in combination with a printer 200, a method of using a test print output of a printer unit or an actual copy output is also conceivable. . Also in this case, as a reference chart, FIG.
Those shown in (a) and (b) can be used. Also,
As described above, in order to uniformly blur the printed black DOT by optically blurring it, it is better to use an auxiliary device for supporting the reference chart by floating it slightly instead of directly placing it on the platen glass. There are cases.

[0086]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, etc.), an apparatus (for example, a copying machine, Facsimile machine, etc.).

Further, an object of the present invention is to supply a storage medium (or a recording medium) in which program codes of software for realizing the functions of the above-described embodiments are recorded to a system or an apparatus, and to provide a computer (a computer) of the system or the apparatus. Or a CPU or MPU) reads out and executes the program code stored in the storage medium,
Needless to say, this is achieved. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.
In addition, by the computer executing the readout program code, not only the functions of the above-described embodiments are realized, but also based on the instructions of the program code,
The operating system (OS) running on the computer performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

Further, after the program code read from the storage medium is written into the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

[0089]

As described above, according to the present invention, in the linear image sensor of the left-right divided reading system,
It is possible to eliminate the step of the signal, which is the drawback.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a partial configuration of an image reading apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of the image reading device according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a white reference plate and a gray reference plate according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining a joint correction method according to the first embodiment of the present invention.

FIG. 5 is a graph showing a content example of an LUT according to the first embodiment of the present invention.

FIG. 6 is a diagram for explaining a problem in the first embodiment of the present invention.

FIG. 7 is a diagram for explaining a method for solving the problem shown in FIG. 6;

FIG. 8 is a block diagram illustrating a configuration of an image reading device according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating an example of a reference chart according to the second embodiment of the present invention.

FIG. 10 is a graph showing a content example of an LUT according to the second embodiment of the present invention.

FIG. 11 is a block diagram illustrating a configuration example when an image reading apparatus according to a second embodiment of the present invention is connected to a printer unit.

FIG. 12 is a diagram showing a configuration of a conventional linear CCD image sensor.

FIG. 13 is a diagram illustrating a configuration example of a conventional image reading apparatus.

FIG. 14 is a diagram showing another configuration of a conventional linear CCD image sensor.

15 is a timing chart showing driving signals of the linear CCD image sensor shown in FIG. 14 and signals output from the linear CCD image sensor.

[Explanation of symbols]

1-4 amplifier 5-8 A / D conversion circuit 9-12 black offset / shading correction circuit 13-16 LUT 17 first memory 19 second memory 20 CPU 100, 100 'image reading device 101, 301 light receiving pixel column 102, 103, 302 to 305 Analog shift register 104, 105, 306 to 309 Output amplifier 113 Reference chart 201 Platen glass 202 Document 203 Illumination lamp 204 to 206 Mirror 207 Lens 208 Linear image sensor 209 Image sensor drive circuit 210 White plate 701 Gray reference Board

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/407 H04N 1/04 103E 1/40 101E F-term (Reference) 2H108 AA01 CA01 CB01 2H110 CD02 CE02 CE08 5B047 AA01 BB02 BC14 CA05 DA04 DA06 5C072 AA01 BA08 DA12 EA05 FB03 FB12 FB15 FB17 FB18 LA15 RA16 UA02 5C077 LL02 MM03 PP06 PP15 RR06 RR19

Claims (42)

[Claims] A linear image sensor that outputs image signals of each of a plurality of divided regions of a light receiving pixel column from separate output terminals corresponding to the respective regions, and a predetermined image signal that is output from each of the output terminals. A plurality of signal processing means provided for each region to perform signal processing; a reference white plate; a reference density member having a predetermined halftone density; and a plurality of reference density members when the reference white plate is read. The level of the image signal output from the plurality of signal processing units is changed to the second level when the level of the image signal output from the signal processing unit is substantially matched with the first predetermined level and the reference density member is read. And a level of an image signal corresponding to a density other than the density of the reference white plate and the density of the reference density member is adjusted to a level obtained by interpolating between the first and second predetermined levels. Adjustment data obtaining means for respectively obtaining adjustment data to be performed for each of the plurality of signal processing means; and adjusting means for adjusting image signals output from the corresponding plurality of signal processing means using the adjustment data. An image reading apparatus characterized by the above-mentioned. 2. A document table on which a document to be read is placed; a linear image sensor for reading image signals of each of a plurality of divided light receiving pixel rows from separate output terminals corresponding to the respective areas; A plurality of signal processing means for performing predetermined signal processing on the image signals output from the respective terminals, provided for each region, a reference white plate, and a reference density member having a predetermined halftone density; Control means for controlling the linear image sensor to read the reference density member when placed on a table; and image signals output from the plurality of signal processing means when the reference white plate is read. And when the reference density member is read, the levels of the image signals output from the plurality of signal processing means are changed to a second predetermined level. Adjustment data for adjusting the level of the image signal corresponding to other than the density of the reference white plate and the reference density member to a level obtained by interpolating between the first and second predetermined levels. An image, comprising: an adjustment data acquisition unit that is obtained for each of a plurality of signal processing units; and an adjustment unit that adjusts image signals output from the corresponding plurality of signal processing units using the adjustment data. Reader. 3. The image reading apparatus according to claim 1, wherein at least one of the first and second predetermined levels is set in advance. 4. The apparatus according to claim 1, wherein the first predetermined level is an average value of signal levels obtained from the plurality of signal processing units when the reference white plate is read. Image reading device. 5. The apparatus according to claim 1, wherein the first predetermined level is a maximum value of signal levels obtained from the plurality of signal processing units when the reference white plate is read. Image reading device. 6. The apparatus according to claim 1, wherein the first predetermined level is a minimum value of a signal level obtained from the plurality of signal processing units when the reference white plate is read. Image reading device. 7. The apparatus according to claim 1, wherein the second predetermined level is an average value of signal levels obtained from the plurality of signal processing units when the reference density member is read. An image reading device according to any one of the above. 8. The apparatus according to claim 1, wherein the second predetermined level is a maximum value of signal levels obtained from the plurality of signal processing units when the reference density member is read. An image reading device according to any one of the above. 9. The apparatus according to claim 1, wherein said second predetermined level is a minimum value of a signal level obtained from said plurality of signal processing means when said reference density member is read. An image reading device according to any one of the above. 10. The first predetermined level is a maximum value of signal levels obtained from the plurality of signal processing units when the reference white plate is read, and the second predetermined level is the reference density. 3. The image reading apparatus according to claim 1, wherein a signal level obtained by reading the member is a minimum value of a signal level obtained from the plurality of signal processing units. 11. The apparatus according to claim 1, wherein the adjustment data obtaining unit obtains the adjustment data such that each of the maximum levels of the image signals obtained from the plurality of signal processing units is the maximum level after the adjustment. 11. The image reading device according to any one of claims 1 to 10. 12. The image reading apparatus according to claim 1, wherein the interpolation is a linear interpolation based on the first and second predetermined levels. 13. The image reading apparatus according to claim 1, wherein the interpolation is a curve interpolation based on the first and second predetermined levels. 14. The image reading apparatus according to claim 1, wherein the interpolation is performed by calculation. 15. The image reading apparatus according to claim 1, wherein the adjustment data is an LUT. 16. The linear image sensor according to claim 1, wherein the linear image sensor has a left-right separated reading structure.
5. The image reading device according to any one of 5. 17. The image reading apparatus according to claim 1, wherein each of the plurality of signal processing units includes an amplification unit that amplifies a signal output from the output terminal. 18. The apparatus according to claim 1, wherein each of said plurality of signal processing means includes A / D conversion means for converting a signal output from said output terminal from an analog signal to a digital signal. An image reading device according to any one of the above. 19. The image reading apparatus according to claim 2, wherein the image reading apparatus is connected to a printing apparatus, and the reference density member is printed by the printing apparatus. 20. The image reading apparatus according to claim 1, wherein said reference density member has at least one or more uniform density pattern portions. 21. The image reading apparatus according to claim 19, wherein the image reading apparatus is integrated with the printing apparatus. 22. A linear image sensor for outputting an image signal of each of a plurality of divided regions of a light receiving pixel column from separate output terminals corresponding to each region, and a predetermined image signal output from each of the output terminals. A method for adjusting an image signal in an image reading apparatus having a plurality of signal processing means for performing signal processing provided for each region, a reference white plate, and a reference density member having a predetermined density of halftone. A first reading step of reading the reference white plate by the linear image sensor, performing signal processing by the plurality of signal processing units and outputting an image signal, and reading the reference density member by the linear image sensor; A second reading step of performing signal processing by a plurality of signal processing means and outputting an image signal; and a first reading step and a second reading step. The level of the image signal output in the first reading step is made substantially equal to a first predetermined level, and the level of the image signal output in the second reading step is changed to a second level. Adjustment data for causing the level of the image signal corresponding to other than the density of the reference white plate and the reference density member to be substantially equal to a predetermined level, and adjusting the level of the image signal to a level obtained by interpolating between the first and second predetermined levels. An adjustment data acquiring step for each of the plurality of signal processing units; and an adjusting step of adjusting image signals output from the corresponding plurality of signal processing units using the adjustment data. How to adjust the image signal. 23. A document table on which a document to be read is placed, a linear image sensor for reading image signals of each of a plurality of divided light receiving pixel rows from separate output terminals corresponding to the respective areas, and A method for adjusting an image signal in an image reading apparatus having a plurality of signal processing means provided for each area and a reference white plate, which performs predetermined signal processing on an image signal output from each terminal. A first reading step of reading the reference white plate by the linear image sensor, performing signal processing by the plurality of signal processing units and outputting an image signal, and a predetermined density of a halftone placed on the platen. A second reading step of reading the reference density member having by the linear image sensor, performing signal processing by the plurality of signal processing units, and outputting an image signal; On the basis of the image signals obtained in the first and second reading steps, the level of the image signal output in the first reading step is made substantially equal to a first predetermined level, and in the second reading step, The level of the output image signal is made to substantially match the second predetermined level, and the level of the image signal corresponding to a density other than the density of the reference white plate and the reference density member is interpolated between the first and second predetermined levels. An adjustment data obtaining step of obtaining adjustment data for adjusting the level to be obtained for each of the plurality of signal processing units; and adjusting the image signals output from the corresponding plurality of signal processing units using the adjustment data. And adjusting the image signal. 24. The method according to claim 22, wherein at least one of the first and second predetermined levels is set in advance. 25. The method according to claim 22, further comprising a step of obtaining, as the first predetermined level, an average value of signal levels obtained from the plurality of signal processing means in the first reading step. 3. The method for adjusting an image signal according to item 1. 26. The apparatus according to claim 22, further comprising a step of obtaining, as the first predetermined level, a maximum value of signal levels obtained from the plurality of signal processing means in the first reading step. 3. The method for adjusting an image signal according to item 1. 27. The method according to claim 22, further comprising the step of obtaining, as the first predetermined level, a minimum value of signal levels obtained from the plurality of signal processing means in the first reading step. 3. The method for adjusting an image signal according to item 1. 28. The method according to claim 22, further comprising a step of calculating, as the second predetermined level, an average value of signal levels obtained from the plurality of signal processing means in the second reading step. The image signal adjusting method according to any one of the above. 29. The method according to claim 22, further comprising a step of obtaining, as the second predetermined level, a maximum value of signal levels obtained from the plurality of signal processing means in the second reading step. The image signal adjusting method according to any one of the above. 30. The method according to claim 22, further comprising a step of obtaining, as the second predetermined level, a minimum value of signal levels obtained from the plurality of signal processing units in the second reading step. The image signal adjusting method according to any one of the above. 31. As the first predetermined level, a maximum value of signal levels obtained from the plurality of signal processing means in the first reading step d is obtained, and the second reading is performed as the second predetermined level. 24. The image signal adjustment method according to claim 22, further comprising a step of obtaining a minimum value of a signal level obtained from the plurality of signal processing units in the step. 32. In the adjustment data obtaining step, the adjustment data is obtained such that each of the maximum levels of the image signals obtained from the plurality of signal processing means becomes the maximum level after the adjustment. 32. The method for adjusting an image signal according to any one of the above items. 33. The image signal adjusting method according to claim 22, wherein said interpolation is linear interpolation based on said first and second predetermined levels. 34. The method according to claim 22, wherein the interpolation is a curve interpolation based on the first and second predetermined levels. 35. The method according to claim 22, wherein the interpolation is performed by calculation. 36. The method according to claim 22, wherein the adjustment data is an LUT. 37. The image signal adjusting method according to claim 22, wherein said linear image sensor has a left-right separated reading structure. 38. The adjustment of an image signal according to claim 22, wherein each of the plurality of signal processing units includes an amplification unit that amplifies a signal output from the output terminal. Method. 39. The apparatus according to claim 22, wherein each of said plurality of signal processing means includes A / M conversion means for converting a signal output from said output terminal from an analog signal to a digital signal. An image signal adjustment method according to any one of the above. 40. The method according to claim 23, further comprising the step of connecting the image reading device to a printing device and printing the reference density member by the printing device. 41. The image signal adjusting method according to claim 22, wherein the reference density member has at least one or more uniform density pattern portions. 42. A storage medium storing a program code for realizing the image signal adjusting method according to claim 22.