JPH11127311A - Image reading device - Google Patents

Abstract

(57) [Problem] To provide an image reading apparatus that automatically cuts out an image even if a read target image of an arbitrary size is placed at an arbitrary position in a readable range. . SOLUTION: A read start line and an end line in an image sensor sub-scanning direction are detected by providing a read line detecting unit, and a start pixel and an end of an image to be read in an image sensor main scanning direction are detected by providing a read pixel detecting unit. Detect pixels. Even if a read target image of an arbitrary size is placed at an arbitrary position, a clipped image is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus using an image sensor or the like.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional image reading apparatus.

In FIG. 3, 1 is a driving device, 2 is a driving device control unit, 3 is an image sensor, 4 is an image sensor control unit, 5 is a buffer memory, 6 is a buffer memory control unit, and 7 is a buffer memory control unit. Indicates a host computer.

Conventionally, in an image reading apparatus in which the reading surface is directed to outside light, the effective reading range is designated by the host computer 7 and the effective reading range is determined regardless of the position and size of the image to be read. Are read out, transferred as pixel data to the host computer 7, and the host computer 7 performs a software program process to cut out the image to be read. In this case, the host computer 7 needs the following memory area Q to store the read pixel data.

Q = X × Y × Z X: The number of pixels in the main scanning direction of the image sensor Y: The number of lines in the sub-scanning direction of the image sensor Z: Gray scale (bit) per pixel Q: Memory area (bit) In order to perform the cutout processing, a work memory area for the processing is required.

FIG. 6 is an image diagram showing a pixel storage memory area on a host computer 7 in a conventional image reading apparatus.

[0007] Reference numeral 11 denotes a readable range, 12 denotes an image to be read, 13 denotes a memory area for storing pixels on the host computer 7, and 16 denotes a read effective range designated by the host computer 7. As described above, the user places the image to be read 12 at an arbitrary position within the effective reading range specified by the host computer 7, performs the reading operation, and stores obviously invalid pixels in the host computer 7.

FIG. 9 is a flowchart showing a processing procedure of the conventional image reading apparatus. Information on the number of moving lines from the host computer 7 to the reading start position and the number of lines required for reading is notified to the drive device control means 2, the image sensor control means 4, and the buffer memory control means 6,
Start operation. The drive device 1 moves the image sensor 3 from the home position to the reading start position.
Next, the light source of the image sensor 3 is turned on by the image sensor control means 4, the reading operation of the image 12 to be read is started, and the pixels read from the image sensor 3 are written into the buffer memory 5 by the buffer memory control means 6. . While controlling the movement to the next line, the drive device control means 2 determines whether or not the number of read lines specified by the host computer 7 has been reached by a counter set internally. The operation is performed, and when it reaches, the reading operation is ended, the image sensor 3 is returned to the home position, and all the operations are ended.

[0009]

However, in such an image reading apparatus, when an image to be read has an arbitrary size,
If the position of the image to be read cannot be specified by the user's will, regardless of the size and position of the image to be read,
All pixels in the effective reading range specified by the host computer must be transferred to the host computer, and a memory area for storing the pixels must be secured on the host computer. Therefore, the invalid pixels are transferred from the image sensor to the host computer, and the memory area on the host computer needs to store the pixels that are apparently invalid for the image to be read, Unless the clipping process is performed, it is not possible to perform an arithmetic process on valid pixels. Further, since the light source is turned on and performs a reading operation from a position distant from the place where the user places the image to be read, the user is confused because the reading start position is different from the image to be read, and the user interface is preferable. Had the disadvantage of not having.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention uses external light to a reading surface as a secondary light source of an image sensor and reads data from the image sensor while reading data from the image sensor in a sub-scanning direction. The edge of the image to be read is detected, and only the pixels within the target range are transferred to the host computer. By this processing, unnecessary transfer is reduced, and the memory area stored on the host computer can be minimized for the image to be read.
The working memory area is minimized, and system resources can be used efficiently. In addition, since it is not necessary to cut out the image in the sub-scanning direction, the processing speed of the entire image processing can be improved.

In addition, the present invention further reduces unnecessary transfer by transferring only effective pixels in the main scanning direction of the image sensor, and reads a memory area stored on a host computer as a read target. Since images are kept to a minimum, the working memory area is also minimized, and system resources can be used efficiently. In addition, since the image clipping process is not required at all, the processing speed of the entire image processing can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, there is provided an image sensor control means for turning off / on a light source in a state where an image sensor is stopped on the same line; On the other hand, read line detecting means for detecting a read start line and a read end line of a read target image, drive device control means for controlling the position of an image sensor in conjunction with the read line detecting means,
A buffer memory for temporarily storing pixels read up to a read start line or a read end line by the read line detection means; and a buffer memory control means for controlling writing and reading of the buffer memory. It is an image reading device that reduces unnecessary memory transfer and minimizes the memory area stored on the host computer for the image to be read.
The working memory area is minimized, and system resources can be used efficiently. In addition, since there is no need to cut out an image in the sub-scanning direction, the processing speed of the entire image processing can be improved.

According to a second aspect of the present invention, in the first aspect of the present invention, a reading line detecting means is provided, and a reading start pixel corresponding to an image to be read is provided in the main scanning direction of the image sensor. A read pixel detecting unit that detects a read end pixel; and a buffer memory control unit that stores an effective pixel in a buffer memory in conjunction with the read pixel detecting unit or controls reading from the buffer memory. An image reading device that transfers only valid pixels in the main scanning direction of the image sensor, thereby further reducing unnecessary transfer and storing the memory area stored on the host computer for the image to be read. Since it is minimized, the working memory area is also minimized, and the system resources can be used efficiently. Also, since there is no need to cut out the image at all,
The processing speed of the entire image processing can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a configuration diagram in a first embodiment of the present invention.

In FIG. 1, 1 is a driving device, 2 is a driving device control means, 3 is an image sensor, 4 is an image sensor control means, 5 is a buffer memory, 6 is a buffer memory control means, 7 is a host computer, and 8 is a host computer. 5 shows a reading line detection unit for detecting a reading effective range of the image sensor 3 in the sub-scanning direction.

FIG. 4 is an image diagram showing a memory area for storing pixels on the host computer 7 in the embodiment.

In FIG. 4, reference numeral 11 denotes a readable range;
Denotes a read target image, 13 denotes a pixel storage memory area on the host computer, and 14 denotes a read effective line range for the read target image 12.

The user places the image 12 to be read in the readable range 11 and starts the reading operation. That is, the host computer 7 issues a reading operation start command to the driving device control means 2 and the image sensor control means 4. Next, the drive device 1 is operated by the drive device control means 2, and the image sensor 3 is moved from the home position position by the set line unit. A control signal corresponding to the specifications of the image sensor 3 is sent from the image sensor control unit 4 to the image sensor 3, and the pixels are read from the image sensor 3 in a state where the light source of the image sensor 3 is turned off. 8 is transferred. The read line detecting means 8 compares the read pixels of the entire line with the pixels obtained in the previous line,
It is determined whether the image sensor 3 has reached the position where the image 12 to be read is placed. If it has not arrived, the controller controls the driving device control means 2 so that the image sensor 3 is continuously moved. Next, as a result of the comparison,
If it is determined that the image has reached the position where the image 12 to be read is located, the reading line detecting means 8 issues an instruction to perform a reading operation from this line to the image sensor control means 4 and the buffer memory control means 6. . The image sensor control unit 4 turns on the light source of the image sensor 3 and starts reading the image 12 to be read. The buffer memory control means 6 stores the read pixels in the buffer memory 5
Write to. Next, the image sensor 3 is driven by the driving device 1.
Moves to the next line. The image sensor control unit 4 turns off the light source of the image sensor 3, transfers the read pixel to the read line detection unit 8, compares the previous line pixel, and determines whether the image sensor 3 is within the range of the image 12 to be read. Judge. When it is determined that the image is within the range of the image to be read 12, the light source is turned on, and the reading operation for the image to be read 12 is performed. The above operation is repeated until the range of the image to be read 12 is exceeded. If it is determined that the image sensor 3 is not within the range of the image 12 to be read, the drive control means 2 controls the drive 1 while turning off the light source, returns the image sensor 3 to the home position, and ends the reading operation. I do. The drive control means 2 notifies the host computer 7 of the end of the moving operation. The buffer memory control means 6 stores the image to be read 12
Is notified to the host computer 7. As the buffer memory 5, a general-purpose memory for storing data by specifying an address, a memory for buffering without specifying an address, for example, a FIFO memory (File)
st in FirstOut memory) or the like may be used. The host computer 7 can assemble an image by obtaining information on the number of valid lines and the end of transfer from the buffer memory control unit 6.

FIG. 7 is a flowchart showing the processing procedure of the present invention. Hereinafter, the processing procedure will be described in detail.

When a command for starting the reading operation is given from the host computer 7 to the drive control means 2 and the image sensor control means 4, the drive control means 2 moves the image sensor 3 by the number of steps of the line corresponding to the resolution. . The pixels on the reading surface are read with the light source turned off. Let the value of this pixel be Vd. The image sensor control unit 4 reads out the pixels while the light source of the image sensor 1 is turned off during the line movement time cycle and transfers the pixels for one line to the read line detection unit 8. Assuming that the value of an arbitrary pixel read at this time is Vd, this operation is performed until the readable range 11 is reached. Vd is a pixel value when nothing is placed on the reading surface. Assuming that the value of the pixel read after reaching the readable range 11 is Vd + n, if the read target image is on the read line, the secondary light source is blocked by the read target image. The following changes occur.

Vd + n <Vd (1) Vs = Vd−Vd + n (2) Vp1 ≦ Vs ≦ Vp2 (3) At this time, the read line detecting means 8 requires that the read target image 12 exists on the line. And the image sensor control means 4 turns on the light source of the image sensor 3. At the same time, the read line detecting means 8 also notifies the buffer memory control means 6 that the read pixels are valid, gives write timing to the buffer memory 5 from the buffer memory control means 6, and outputs the pixels read from the image sensor 3. Is temporarily stored in the buffer memory 5. In this manner, the light source is repeatedly turned off and turned on on the same position line, the presence or absence of the image to be read is detected when the light source is turned off, and the operation of storing the pixels of the image to be read in the buffer memory is repeated when turned on.

The value of Vs in the equation (2) is the difference between the value Vd when nothing is placed on the reading surface (open state) and the value Vd + n in the presence of the image to be read. Is changed according to the illuminance, and it is compared whether Vs falls between the value Vp1 and the value Vp2 as shown in the equation (3). Vp1 and Vp2 are parameters that change according to the illuminance of external light.

When the position of the image sensor 3 deviates from the range of the image 12 to be read, the value of Vs does not satisfy the equation (3). The means 6 is notified of the end of the reading operation. The drive control means 2 returns the image sensor 3 to the home position with respect to the drive 1 based on this notification. The buffer memory control means 6 ends the write operation to the buffer memory 5 based on this notification.
When the buffer memory 5 is a FIFO or the like, the number of read operations from the host computer 7 is counted, and when the number of valid lines has been reached, the buffer memory control means 6 notifies the host computer 7 of completion. In addition, by notifying the number of valid lines, the host computer 7 can smoothly perform the image assembling process.

The comparison between Vd and Vd + 1 is not limited to the comparison between adjacent lines, but may be performed, for example, on three consecutive lines. If the accuracy of the comparison is not good, a good result can be obtained by making a determination based on a value shift (slope of a pixel value change) instead of a determination based on a simple comparison result.

Next, a second embodiment of the present invention will be described with reference to the drawings. (Embodiment 2) FIG. 2 is a configuration diagram in a second embodiment of the present invention.

In FIG. 2, reference numeral 9 denotes a read pixel detecting means for detecting an effective read pixel for the image 12 to be read by the image sensor 3. The principle of determining whether the read pixel corresponds to the read target image 12 is the same as in the first embodiment. Information is provided to the buffer memory control means 6 in the main scanning direction of the image sensor 3 to indicate that the pixel is effective from the Mth pixel to the Nth pixel, and the pixel is written to the buffer memory 5 or the buffer memory 5 By controlling either one of the reading operations, only the effective pixels in the main scanning direction are transferred to the host computer 7. Further, only the pixels of the valid line are transferred by the read line detecting means 8 in the same procedure as in the first embodiment, so that only the two-dimensional valid pixels for the image 12 to be read are transferred to the host computer 7.
Can be transferred to

FIG. 5 is an image diagram showing a pixel storage memory area on the host computer 7 according to the present invention.

In FIG. 5, reference numeral 15 denotes the image sensor 3.
5 shows a read effective pixel range in the main scanning direction in FIG.

The image reading apparatus starts the reading operation with the image to be read 12 placed in the readable range 11 by the user. That is, the host computer 7 issues a reading operation start command to the driving device control means 2 and the image sensor control means 4. Next, the drive device 1 is operated by the drive device control means 2, and the image sensor 3 is moved from the home position position by the set line unit. A control signal according to the specifications of the image sensor 3 is sent from the image sensor control unit 4 to the image sensor 3, and one line of pixels is read from the image sensor 3 with the light source of the image sensor 3 turned off. The data is transferred to the reading line detecting means 8 and the reading pixel detecting means 9. The operation of the reading line detecting means 8 is the same as that of the first embodiment.
Is the same as On the other hand, the read pixel detecting means 9 detects an effective pixel in the main scanning direction where the image 12 to be read is placed by comparing values of adjacent pixels among the read pixel values. Once detected, as long as the image sensor 3 is within the range of the image to be read, the information of the effective pixels is stored and either when writing to the buffer memory 5 or when reading from the buffer memory 5 to the host computer 7. , Effective pixel data in the main scanning direction may be transferred. Buffer memory control means 6
Notifies the host computer 7 of the start and end points of the effective pixels detected in the main scanning direction for the image 12 to be read.
An image can be assembled by the host computer 7 based on this information.

FIG. 8 is a flowchart showing a processing procedure according to the second embodiment of the present invention.

Hereinafter, the processing procedure will be described in detail.
The operation of detecting the reading start position by the reading line detecting means 8 is the same as in the first embodiment. Image 12 to be read
After detecting the read start line for the read line, the read line detecting means 8 enables the operation of the read pixel detecting means 9. That is, the read pixel detecting means 9 compares the values of pixels adjacent in the main scanning direction. Now, assuming that the n-th pixel value is Vn and the adjacent pixel value is Vn−1 or Vn + 1, Vn <Vn−1 (4) Vn> Vn + 1 (5) Vp1 <Vn−1− Vn <Vp2 (6) Vp1 ≦ Vn−Vn + 1 ≦ Vp2 (7) In the case of Expression (4), the n-th pixel is a starting point of an effective pixel, and is expressed by Expression (5). In this case, the n-th pixel is the end point of the effective pixel. This determines the effective pixels in the main scanning direction. Vp1 and Vp2 are parameters that change depending on external light. These information are stored in the buffer memory control means 6
Will be notified. Next, the light source of the image sensor 3 is turned on, and the read pixels are transferred to the buffer memory 5.
The valid pixels detected by the read pixel detecting means 9 are written to the buffer memory 5 or the valid pixels are read from the buffer memory 5 to the host computer 7 according to the control method of the buffer memory detecting means 6. Subsequent processing is the same as in the first embodiment. The buffer memory control unit 6 notifies the host computer 7 of the number of valid lines, the valid start pixel, and the valid end pixel, so that the host computer 7 can smoothly perform an image assembling process.

In addition to the comparison between adjacent pixels such as Vn and Vn-1 or Vn + 1, for example, it is possible to make three consecutive pixels into one set and compare the three adjacent pixels. If the accuracy of the comparison is not good, a good result can be obtained by making a determination based on a value shift (slope of a pixel value change) instead of a determination based on a simple comparison result. Alternatively, the accuracy of position detection of the image to be read can be improved by comparing a set of 3 × 3 pixels in the main scanning direction and the sub-scanning direction as one unit in conjunction with the reading line detection unit. It is.

[0033]

As described above, according to the present invention, the user can freely read an image within the readable range without worrying about the position of the image to be read. .

Further, since the memory storage processing according to the effective range of the image is performed, invalid data transfer to the memory is eliminated, so that the image clipping processing by software processing becomes unnecessary, and the overall speed of image processing is improved. Can be provided. In addition, the user can automatically detect the position of the image and perform a reading operation, thereby improving the user interface.

[Brief description of the drawings]

FIG. 1 is a configuration diagram according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional image reading apparatus.

FIG. 4 is an image diagram showing a memory area for storing pixels according to the first embodiment of the present invention;

FIG. 5 is an image diagram showing a pixel storage memory area according to the second embodiment of the present invention;

FIG. 6 is an image diagram showing a memory area for storing pixels in a conventional image reading apparatus.

FIG. 7 is a flowchart showing a processing procedure according to the first embodiment of the present invention;

FIG. 8 is a flowchart showing a processing procedure according to the second embodiment of the present invention;

FIG. 9 is a flowchart showing a processing procedure of a conventional image processing apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 drive device 2 drive device control means 3 image sensor 4 image sensor control means 5 buffer memory 6 buffer memory control means 7 host computer 8 read line detection means 9 read pixel detection means 11 readable range 12 image to be read 13 on host computer Memory area for pixel storage 14 Effective read line range 15 Effective read pixel range 16 Read line range specified by host computer

Claims (2)

[Claims] In an image reading apparatus using a line sensor such as an image sensor, an image sensor control means for turning off and on a light source while the image sensor is stationary on the same line, and in a sub-scanning direction of the image sensor. On the other hand, read line detecting means for detecting a read start line and a read end line of an image to be read, drive control means for controlling the position of an image sensor in conjunction with the read line detect means, and read line detect means An image reading apparatus comprising: a buffer memory for temporarily storing pixels read up to a read start line or a read end line, and buffer memory control means for controlling writing and reading of the buffer memory. 2. The image sensor according to claim 1, wherein:
Read pixel detection means for detecting a read start pixel and a read end pixel corresponding to an image to be read, and a buffer for storing effective pixels in a buffer memory in conjunction with the read pixel detection means or for controlling reading from the buffer memory The image reading device according to claim 1, further comprising a memory control unit.