JP2001203859A - Device and method for reading image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader capable of highly accurately reading an image, without requiring highly accurate feeding operation in sub-scan direction. SOLUTION: Image processing for every main scan is performed by performing main scanning by electronic scanning in the lengthwise (arrow (a)) direction of a line sensor 1 and performing sub-scanning by relatively moving the line sensor 1 and an original 11 in the direction (arrow (b)) perpendicular with the lengthwise direction, a reference image having prescribed marks at equal intervals in the sub-scanning direction is provided within an effective read range (arrow (a)) in the main scan direction of the line sensor 1, the reference image is read by the line sensor 1, together with an original image and the intervals of the marks are recognized from the read image. Then, the image correction of the original image is performed, on the basis of the dispersed result of feeding velocity in the sub-scan direction with a motor 6 calculated from the recognized intervals of marks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image reading apparatus such as a scanner and an image reading method.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus such as a scanner performs a main operation electrically and at the same time performs a sub-operation by a relative movement between a line sensor and a read image. There is a demand for an accurate feed speed by using a motor control at a constant speed drive by a precise feed operation and speed control and by employing a highly accurate feed mechanism in the sub-scanning direction.

[0003]

However, in the conventional image reading apparatus as described above, a high-precision motor must be used as the motor, and the driving circuit of the motor must be complicated. There has been a problem that it is disadvantageous for cost reduction.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an image reading apparatus capable of reading an image with high accuracy without requiring a high-precision feed operation in the sub-scanning direction. And an image reading method.

[0005]

An image reading apparatus and an image reading method according to the present invention are configured as follows.

(1) In an image reading apparatus, a line sensor for reading a document image, and a main scanning by electronic scanning in a longitudinal direction of the line sensor, and the line in a direction perpendicular to the longitudinal direction. Image processing means for performing image processing for each main scan by performing sub-scanning by relative movement between the sensor and the document, and at equal intervals in the sub-scanning direction within the effective reading range of the line sensor in the main scanning direction. A reference image having a predetermined mark is provided, and the reference image is read together with the document image by the line sensor.

(2) In the image reading apparatus of the above (1), a recognizing means for recognizing a mark interval from the read image and a motor in the sub-scanning direction calculated from the mark interval recognized by the recognizing means. And an image correcting means for correcting the image of the original image based on the result of the variation of the feeding speed.

(3) In the image reading device of (1) or (2), the feed speed in the sub-scanning direction is set to a speed lower than the feed speed in the sub-scanning direction for reading at a desired resolution. The means thins out the read document image data.

(4) In the image reading method, the main scanning is performed by electronic scanning in the longitudinal direction of the line sensor for reading the original image, and the line sensor and the original in a direction perpendicular to the longitudinal direction are connected. In addition to performing image processing for each main scan by performing sub-scanning by relative movement, a reference image having predetermined marks at regular intervals in the sub-scanning direction is provided within an effective reading range of the line sensor in the main scanning direction. The reference image is read together with the original image by the line sensor.

(5) In the image reading method of the above (4), a mark interval is recognized from the image read by the recognition means, and a motor calculated from the mark interval recognized by the recognition means by the image correction means. The image correction of the original image is performed based on the result of the variation of the feed speed in the sub-scanning direction.

(6) In the image reading method of (4) or (5), the feed speed in the sub-scanning direction is set to a speed lower than the feed speed in the sub-scanning direction for reading at a desired resolution. The means thins out the read document image data.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, for the sake of simplicity, a case in which the line sensor is movable as the sub-scanning operation will be described as an example.

(First Embodiment) FIG. 1 is a block diagram showing a configuration of a scanner according to a first embodiment. FIG. 2 is a flowchart showing an image reading and reading operation by the configuration of FIG. The basic configuration and operation will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes a line sensor (CCD) for reading an image in the main scanning direction. Reference numeral 2 denotes a signal processing unit including an amplifier for performing analog signal processing on the signal output of the line sensor 1. Reference numeral 3 denotes an A for converting an analog signal output signal of the signal processing unit 2 into a digital signal.
/ D converter.

Reference numeral 4 denotes an image processing unit (image processing means) that performs arithmetic processing on the digital signal output of the A / D converter 4 and outputs the digital signal as digital image data. 5 is a line sensor 1
Is a feed mechanism for scanning in a sub-scanning direction, which is a direction perpendicular to the sub-main scanning direction. Reference numeral 6 denotes a sub-scanning motor for moving the feed mechanism unit 5 and performing a sub-scanning operation. Reference numeral 7 denotes a motor driver that drives the sub-scanning motor 6.

Reference numeral 8 denotes a speed controller for controlling the motor driver 7 to feed the sub-scanning motor 6 and the feed mechanism 5 at a constant speed. Reference numeral 9 denotes a CPU that controls the image processing unit 4 and the speed control unit 8. A sensor 14 detects that the line sensor 1 has reached the end in the sub-scanning direction.

An image reading operation according to the above configuration will be described with reference to FIG. This operation will be described based on a program stored in a ROM (not shown) in accordance with an instruction from the CPU 9.

Normally, in order to prevent the read image from being bent and read by the scanner, not only the mechanical precision of the feed mechanism is increased, but also the line sensor 1 must be moved in the sub-scanning direction at a constant feed speed. Therefore, first, in step S101, the CPU 9 sets a desired resolution. Next, in step S102, the CPU 9 drives the motor 6 and the feed mechanism 5 to perform a sub-scan at a constant speed so as to have a feed speed for obtaining a desired resolution.
Is set, and the motor feed speed of the motor driver 7 is set.

In step S103, the sub-scanning motor 6 is operated to perform sub-scanning, and the line sensor is moved at a constant feed speed. In addition, the line sensor 1 reads an image while electrically performing main scanning, and outputs an analog signal of the read image. Thereafter, the analog signal output in step S104 is subjected to signal processing in the signal processing unit 2, converted from an analog signal to a digital signal in the A / D converter 3, and processed by the image processing unit 4 under the instruction of the CPU 9. Then, the image data is output as digital image data in step S105.

Subsequently, in step S106, when the line sensor 1 moves to the end in the sub-scanning direction and the sensor 14 outputs a detection signal to the CPU 9 (YES), step S
Proceeding to 107, the CPU 9 ends the image reading. If it has not reached the end in the sub-scanning direction in step S106 (NO), the process returns to step S103 and repeats the operation.

Next, the features of this operation will be described. FIG.
FIG. 4 is an explanatory diagram showing a configuration of a main part of the scanner according to the first embodiment. The concept at the time of reading will be described with reference to FIG. In the following description, the same components in FIG. 1 will be described using the same reference numerals.

As shown in FIG. 3, the line sensor 1 performs sub-scanning in the direction of arrow b by the feed mechanism 5 and sub-scanning motor 6, and its reading range is indicated by arrow a. 10
Is a reference image indicating reading accuracy, on which marks arranged at equal intervals of length d are written. 11 is a manuscript.

The document 11 and the reference image 10 are spatially located at the same time, and are arranged so as to be completely included in the arrow a which is the reading range of the line sensor 1. Therefore, image reading is performed, and digital image data finally output from the image processing unit 4 is as shown in FIG. 4, and is output in a form in which a reference image is captured in a part of the read image (read image). You.

Here, the number of each image line forming between the marks in the read image is represented by dn (i) (i = 1, 2, 3,..., I,..., N). Here, the image line means image data of one image unit width extending in the main scanning direction. Also,
Let dn be the number of image lines formed in the mark length dimension d at the desired resolution.

There is unevenness in the feed speed in the sub-scanning direction due to variations in the feed mechanism 5, the motor 6, the motor driver 7, and the speed controller 8 as a whole. As a result, FIG.
Dn of each image line constituting the space between marks in
(I) appears in a form that varies by the number of image lines of 0 ± α. In other words, dn−α ≦ dn (i) ≦ dn + α Equation (2) Here, since dn is a known value, each image line number dn
By measuring (i), it is easy to see how much the feed speed unevenness occurs between the marks. Therefore, it is possible to easily know how much the read image is distorted after the image reading operation. It is possible to objectively and easily confirm how much image correction should be performed.

As described above, in this embodiment, the reference images in which the marks are arranged at equal intervals extending in the sub-scanning direction are arranged within the effective reading range in the main scanning direction, and the reference images are read simultaneously with the read images. Therefore, it is possible to confirm the interval between the marks in the obtained read image and objectively recognize the variation in the feed speed. For this reason, the motor, its drive circuit, and the sub-scan feed mechanism can be simplified, and if the original image is corrected based on the recognized variation in the feed speed, the cost can be reduced with high accuracy.

(Second Embodiment) FIG. 5 is a block diagram showing a configuration of a scanner according to a second embodiment, and FIG. 6 is a flowchart showing an image reading operation according to the second embodiment.

In FIG. 5, reference numeral 12 denotes an image recognizing section (recognizing means) for recognizing the output digital image data of the image processing section 4 as an image. Reference numeral 13 denotes an interpolation processing unit (image correction unit) that performs interpolation processing on digital image data output from the image processing unit 4 based on information obtained from the image recognition unit 12. The other configuration is the same as the configuration in FIG.

An image reading operation according to the above configuration will be described with reference to FIG. This operation will be described based on a program stored in a ROM (not shown) in accordance with an instruction from the CPU 9. First, in step S201, the CPU 9 sets a desired resolution. Next, in step S202, the CPU
Reference numeral 9 drives the motor 6 and the feed mechanism 5 to set the motor feed speed of the motor driver 7 so that the feed speed can be obtained to obtain a desired resolution.

In step S203, the sub-scanning motor 6 is operated to perform sub-scanning, and the line sensor is moved at a constant feed speed. In addition, the line sensor 1 performs main scanning electrically and outputs an analog signal of a read image. Thereafter, the analog signal output in step S204 is subjected to signal processing in the signal processing unit 2 and is converted from an analog signal to a digital signal in the A / D converter 3, and the signal processing is performed in the image processing unit 4 under the instruction of the CPU 9. And output as digital image data.

The image at that time will be described with reference to FIG. 4. If the speed control is not performed, the feed speed unevenness exists, and as a result, it appears as a variation in the number dn (i) of each image line. Assuming that 0 ± β, the number dn (i) of each image line constituting each work exists with a variation of dn−β ≦ dn (i) ≦ dn + β (3).

Next, the digital image data output in step S205 is subjected to image recognition of a part of the reference image 10 and a mark in the Kazo image recognition unit 12, and the presence or absence of the mark of the reference image 10 is extracted. Here, in step S206, C
PU 9 is a step S until the mark is extracted (NO).
The operations of 203 to S206 are repeated, and when the mark is extracted (YES), the image data during that time is supplied to the interpolation processing unit 15.

In step S207, the image recognizing unit 14 measures the variation of the number dn (i) of each image line constituting each mark at each interval, and in step S2.
At 08, the variation data dx (i) = (i = 1, 2, 3,..., I,... N) Formula (4) is calculated and supplied to the interpolation processing unit 13. Step S
At 209, the interpolation processing unit 13 sets the variation data dx
Referring to (i), image interpolation is performed so that the original number of constituent image lines dn at the desired resolution is obtained, and step S21 is performed.
At 0, the digital image data is output as uniform digital image data without unevenness in the feed speed in the sub-scanning direction as shown in FIG. If the line sensor 1 moves to the end in the sub-scanning direction in step S211 and the sensor 14 outputs a detection signal to the CPU 9 (YES), the process proceeds to step S212 and the CPU proceeds to step S212.
9 ends the image reading. If it has not reached the end in the sub-scanning direction in step S211 (NO),
Returns to step S203 and repeats the operation.

This makes it possible to obtain digital image data without unevenness in the feed speed in the sub-scanning direction even if speed control is not particularly performed in the sub-scanning operation, and even if there is a variation in the feed mechanism.

In other words, it is not necessary to make the sub-scanning system constituted by the feed mechanism, the sub-scanning motor, and the motor driver particularly high-precision, and the cost can be reduced.

FIG. 6 shows an application of the above-described configuration of the scanner, in which the image recognition section 12 in FIG. The CPU 9 performs image recognition on the digital image data of the image processing unit 4 and calculates the variation data dx (i) as described above. Based on the result, the CPU 9 supplies the variation data dx (i) to the interpolation processing unit 15 to perform the interpolation processing. The same effect can be obtained by the configuration in which the unit 15 performs the interpolation processing.

As described above, in this embodiment, the speed control of the motor in the sub-scanning direction is abolished, and in addition to the above-described first embodiment,
It is possible to reduce the cost by absorbing the interval between marks by image recognition to absorb unevenness in feed speed by image interpolation processing and simplifying the motor, its driving circuit, and the feed mechanism for sub-scanning.

(Third Embodiment) In the present embodiment, the setting of the motor driver 7 in FIG. 5 described above is determined by determining the number dn (i) of each image line constituting a mark that appears as a result of the presence of unevenness in the feed speed. Variation is minimum value = 0, maximum value 2β
It is achieved by setting to be.

More specifically, the feed speed of the motor 6 at the desired resolution may be set lower by a certain amount. Therefore, here, the number dn (i) of each image line constituting the space between marks
Dn ≦ dn (i) ≦ dn + 2β... Exists with a variation of the expression (5).

Here, the variation data dx (i) is set as dx (i) = dn (i) -dn (1 = 1, 2, 3,..., I,... N). It is supplied to the interpolation processing unit 13. Referring to dx (i) in equation (6), the interpolation processing unit performs image interpolation so that the original image line number dn at the desired resolution is obtained.
The final output is uniform digital image data without unevenness in the feed speed in the sub-scanning direction as shown in
In the embodiment, as is derived from Expression (6), dn = dn (i) -dx (i) Expression (7) Therefore, the number d of image lines constituting each marker is d.
Image interpolation is completed by thinning out the number of variation data dx (i) from n (i) at an appropriate interval, and finally output as uniform digital image data without feed speed unevenness in the sub-scanning direction as shown in FIG. It becomes possible.

As a result, it is possible to simplify the configuration of the motor drive system, obtain digital image data free from unevenness in the feed speed in the sub-scanning direction without performing complicated calculations in image interpolation processing.

As described above, in this embodiment, in addition to the above-described second embodiment, the image interpolation (image correction) is performed by setting the motor feed speed of the sub-scanning system so as to obtain a certain appropriate resolution.
Can be performed only by thinning out the image, and an image interpolation process that does not require complicated arithmetic processing can be achieved.

As described above, in the above three embodiments, the case where the line sensor is movable has been described. However, the structure of the sub-scanning system is such that the relative movement between the line sensor and the read image (document) is obtained. The same effect can be obtained as long as the configuration is obtained, regardless of the method.

[0044]

As described above, according to the present invention,
A line sensor for reading a document image, and performing main scanning by electronic scanning in the longitudinal direction of the line sensor and sub-scanning by relative movement between the line sensor and the document in a direction perpendicular to the longitudinal direction. Image processing means for performing image processing for each main scan by performing a reference image having predetermined marks at equal intervals in the sub-scanning direction within the effective reading range of the line sensor in the main scanning direction, Since the reference image is read together with the document image by the line sensor, a highly accurate feeding operation in the sub-scanning direction is not required, and if the document image is corrected based on the read reference image, the image can be read with high precision. Therefore, there is an effect that cost can be reduced.

A recognition means for recognizing a mark interval from a read image, and an original image based on a result of a variation in a feed speed in a sub-scanning direction by a motor calculated from the mark interval recognized by the recognition means. And an image correcting means for performing the image correction described above, so that an image can be read with high accuracy and the cost can be reduced.

Further, the feed speed in the sub-scanning direction is set to a speed lower than the feed speed in the sub-scanning direction for reading at a desired resolution, and the image correcting means thins out the read original image data. There is an effect that complicated arithmetic processing is not required.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a scanner according to a first embodiment.

FIG. 2 is a flowchart illustrating an image reading operation according to the first embodiment.

FIG. 3 is an explanatory diagram illustrating a main configuration of a scanner according to the first embodiment.

FIG. 4 is a view showing a read image according to the first embodiment;

FIG. 5 is a block diagram illustrating a configuration of a scanner according to a second embodiment.

FIG. 6 is a flowchart illustrating an image reading operation according to a second embodiment.

FIG. 7 is a diagram showing a read image subjected to interpolation processing according to the second embodiment.

FIG. 8 is a diagram showing a configuration of a scanner according to a second embodiment.

[Explanation of symbols]

 Reference Signs List 1 line sensor (CCD) 2 signal processing unit 3 A / D converter 4 image processing unit (image processing unit) 5 feed mechanism unit 6 sub-scanning motor 7 motor driver 8 speed control unit 9 CPU 13 interpolation processing unit (image correction unit) ) 14 sensors

Claims (6)

[Claims] 1. A line sensor for reading a document image, and a main scanning is performed by electronic scanning in a longitudinal direction of the line sensor, and a relative position between the line sensor and the document in a direction perpendicular to the longitudinal direction. And image processing means for performing image processing for each main scan by performing sub-scanning by dynamic movement, and having predetermined marks at regular intervals in the sub-scanning direction within the effective reading range of the line sensor in the main scanning direction. An image reading apparatus, wherein an image is provided, and the reference image is read together with a document image by the line sensor. And a recognition unit for recognizing a mark interval from the read image, and an original image based on a result of a variation in a feed speed in a sub-scanning direction by a motor calculated from the mark interval recognized by the recognition unit. 2. The image reading apparatus according to claim 1, further comprising: an image correction unit that performs the image correction. 3. The method according to claim 1, wherein the feed speed in the sub-scanning direction is set to a speed lower than the feed speed in the sub-scanning direction for reading at a desired resolution, and the image correcting means thins out the read document image data. The image reading device according to claim 1 or 2, wherein 4. A main scanning is performed by electronic scanning in a longitudinal direction of a line sensor for reading a document image, and a sub-scanning is performed by a relative movement between the line sensor and the document in a direction perpendicular to the longitudinal direction. To perform image processing for each main scan, and a reference image having predetermined marks at regular intervals in the sub-scanning direction is provided within the effective reading range of the line sensor in the main scanning direction, and the original is scanned by the line sensor. An image reading method, wherein the reference image is read together with an image. 5. The method according to claim 1, wherein the recognition unit recognizes a mark interval from the read image, and the image correction unit calculates a result of a variation in the feed speed in the sub-scanning direction by the motor calculated from the mark interval recognized by the recognition unit. 5. The image reading method according to claim 4, wherein the image of the document image is corrected based on the image. 6. The apparatus according to claim 1, wherein the feed speed in the sub-scanning direction is set to a speed lower than the feed speed in the sub-scanning direction for reading at a desired resolution, and the image correction means thins out the read document image data. The image reading method according to claim 4, wherein the image is read.