JPH0368260A - Picture read scanner - Google Patents

Abstract

PURPOSE:To prevent an effective read area per one scanning from being made narrow by controlling the storage of a binarization data for one scanning in a picture read scanner while taking a processing time delay due to binarization into account. CONSTITUTION:When a video data by one scanning is outputted from an image sensor 5, the video data is binarized by a binarization section 2. The binary data by one scanning is outputted from the binarization section 2 but the output time is delayed by the time used for the binarization. In order to compensate the delay in the output time of the binarization data, a memory control circuit 15 issues a command of storing the binarization data in the timing in matching with the delay to a memory 14 at every binarization data block by one scanning. Thus, the binarization data block for one scanning is stored from the head and the data is stored in the memory 14 in the complete state where the effective data of the rear part is not lost.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention relates to a 0-image reading scanner, in particular, to reduce the processing time delay caused by the binarization of analog video data read by scanning a document. Regarding what I decided to transfer in consideration.

[Conventional technology]

An example of an image reading scanner such as an optical character reader (OCR) is shown in Fig. 3, and the character or graphic data recorded on the @ slip is read by an image sensor S using a charge-coupled device (COD) or the like. The analog video data thus read is optically read by the shading removal circuit 4. A binarization unit 2 consisting of a slice circuit 5 and a masking correction circuit 6 converts the data into binarized data and outputs it to a data buffer 3. In the binarization unit 2, a shading removal circuit 4 removes the influence of light intensity unevenness on the form from the video data, and a slicing circuit 5 removes noise at a level above or below a predetermined slice level. Thereafter, the video data is processed by a masking correction circuit 6, one black (or rob) and one white (rob) for each pixel by a masking correction circuit 6.
or "1"), and an isolated "
Masking correction is performed in which pixels that are "black" (or "0") or pixels that are "white" (or "1") are regarded as noise and removed. Note that the processing by the circuits 4, 5, and 6 requires a time of a time and a time of a2°a, respectively.

The binarized data obtained in this way is used for single image recognition, etc., using DMAC: (direct memory access).
The data is read from the data buffer 3 in response to a transfer command from the controller) 7, and is transferred to the data memory 1 via the bus 8.
It will be transferred to 0. Note that the DMAC7 is
The transfer command is issued in synchronization with the start of video data output by the image sensor S.

The operation per scan in the image reading scanner is as shown in FIG. That is, the image sensor S
(a) by scanning one line on the form.
A video data block VDB corresponding to one scan of n pixels (dots) is output from the sensor S as shown in FIG. At this time, a transfer command is issued from the DMAC 7 to the data buffer 3 in synchronization with the start of output of the video data block VDB, and as shown in (d), the transfer command is issued to the data buffer 3.
The data transfer operation is started.

As described above, the video data output from the image sensor S is converted into binarized data by the binarization unit 2, but the binarized data block BDB for one scan is (b
), the video data block is output from the binarization unit 2 after being delayed by the time A, which is the sum of the times ate a21 and a3, from the time when the video data block is output from the image sensor S. Therefore, from the start of outputting the video data block VDB, two
Regarding the time until the start of output of the digitized data block BDB (that is, time A), even though the data transfer operation of the data buffer 3 is in progress, there is no output of binarized data, and the data buffer 3 In the one-scan data block TDB to be transferred, an invalid data area ND exists prior to a valid data area ED. Therefore, in order to prevent misreading due to the invalid data area ND, as shown in (c) of the binarized data block BDB, the invalid data area ND is set to "black" or "white" according to the background color of the form. Window processing to embed and explicitly disable is done in real time. In this way, the transfer data block TDB for each scan is transferred to the data memory 10, and the memory 10 contains not only the binarized data in the valid data area ED but also the invalidated data in the invalid data area ND. It will be remembered.

Generally, the inclination of a form with respect to the scan direction of an image sensor is called 111-vote skew, while the processing time delay due to binarization as described above is called binarization hard skew. The binarization hard skew has a constant skew value depending on the circuit scale of the binarization section.

[Problem to be solved by the invention]

However, in the conventional image reading scanner, despite the processing time delay due to binarization (i.e., binarization hard skew) as described above, it is difficult for the image sensor S to finish outputting video data for one scan. In response to this, the data transfer operation for the upper scan of the data buffer 3 is also completed, so that the portion of the binarized data block BDB that is output from the binarization unit 2 after the data transfer operation is completed is The data of the end part BDB-R is
Even if the transfer data block TDB is valid, the transfer data block TDB
It will be truncated from. As a result, in the scanner, due to the existence of the binarization hard skew, it is not possible to transfer all of the valid data read by the image sensor S, resulting in a problem that the effective reading area per scan becomes narrow. In particular, in recent image reading scanners, in order to improve reading accuracy, the circuit scale of the binarization section tends to increase, and as the circuit scale increases, the scale of the binarization hard skew also increases. The narrowing of the effective reading area is becoming more and more serious in AIU.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide an image reading scanner that can prevent the effective reading area from being narrowed due to processing time delays due to binarization.

[Means for solving problem a]

In order to achieve the above object, an image scanner according to the present invention includes an optical reading means for scanning a document surface to be read and outputting video data as the scanning result;
binarization processing means for binarizing the video data output from the reading means for each pixel; and binarization processing means for binarizing the video data output from the binarization processing means in units of data blocks for each scan. Taking into consideration the processing time delay occurring in the data storage means to be stored and the binarization processing means, the binarized data for the upper scan is stored in the storage means from the beginning of the data block, It is equipped with a memory control means for reading out the stored binarized data for one scan at a predetermined timing, and can prevent narrowing of the effective reading area caused by a processing time delay caused by the binarization processing means. be.

[Effect]

When video data for one scan is output from the reading means, the video data is binarized by the binarization processing means. In this way, one scan's worth of binarized data is output from the binarization processing means, but the output time is delayed by the time spent on the binarization. Note that this delay is called binarization hard skew.

Therefore, in the present invention, in order to cope with the delay in the output time of the binarized data, for each block of binarized data for one scan, the memory control means sends a message to the data storage means that corresponds to the delay. A command is given to store the binarized data at the appropriate timing. In this way, the data block of the binarized data for the scan can be stored from the beginning thereof, and the valid data in the rear end area is stored in the data storage means in a complete state without being truncated. can be done.

As described above, in the present invention, all of the valid data can be transferred by controlling the storage of one scan's worth of binarized data in consideration of the processing time delay due to binarization.
It is possible to prevent the effective reading area per t-scan from being narrowed due to the processing time delay due to digitization. Also,
By controlling the start of transfer as described above, there is no invalid data area in the transfer data block, and window processing for the binarized data block is also required.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of an image reading device according to the present invention, and the same reference numerals as in FIG.
It performs the same function as the one shown in the figure.

That is, in the image reading device shown in FIG.
Every time an image sensor S using a CD or the like scans the upper line on a form, a video data block VDB of one scan of n pixels is output as shown in FIG. 2(a). In this way.

Video data for each scan is converted into binarized data by a binarization unit 2 comprising a shading removal circuit 4, a slicing circuit 5, and a masking correction circuit 6. In this binarization section 2, each time the video data for each scan is converted, the processing time a1. Since the binarization time A, which is the sum of 'all a,' is required, the output of the binarized data block BDB for one scan is the video data from the image sensor S, as shown in FIG. Binarization time A from block output
only to be delayed.

The shift register 12 performs gino-parallel conversion on the binarized data for each scan serially output from the binarization unit 2 and outputs the converted data to the memory 14 of the transfer control unit 13 .

The memory 14 is a FIFO (first in, first out) memory that can be read and written at high speed, and writes the binary data for the current scan output from the shift register 12 in real time in response to a write command signal WR given from the memory control circuit 15. The writing of the current scan's worth of binary data into the memory 14 is as shown in FIG.
c), only the binarization time A in the binarization unit 2,
This is performed with a delay from the time of output from the sensor S. Also, almost in parallel with the above writing, the memory 14 reads out the previously written binary data for the previous scan and outputs it to the data buffer 3 in response to the read command signal RD given from the memory control circuit 15. It looks like this. Furthermore, the memory 14 is connected to the memory control circuit 1
It is cleared to the initial state by a reset signal R given from 5.

The memory control circuit 15 issues the write command signal WR in synchronization with the start of output of the binary data block BDB for the current scan from the shift register 12, and outputs the write command signal WR to output the video data block VD for the current scan from the image sensor S.
The read command signal RD is generated in synchronization with the start of output of the signal B. In this way, the readout of the binarized data for the previous scan by the memory 4 is performed as shown in FIG. 2(d).
The process is started in synchronization with the start of the output of the current scan's worth of video data VDB, and is completed in synchronization with the completion of output of the current scan's worth of video data VDB.

The control unit 20 operates the entire image reading scanner.

It performs management and control, and instructs the DMAC 7 to directly transfer the binarized data from the data buffer 3 to the data memory IO without going through the control unit 20.

In this way, the DMAC 7 outputs the transfer enable signal TE to the data buffer 3 in synchronization with the start of output of the video data block VDB for one scan from the image sensor S. With this transfer enable signal TE, the data buffer 3 synchronizes with the start of output of the video data block for the current scan by the image sensor S, that is, in synchronization with the start of reading out the binary data of the previous scan by the memory 14. , starts transferring the binarized data for the previous scan. In this way, the transfer data block TDB transferred from the data buffer 3 via the bus 8 includes all the binarized data blocks for the previous scan, as shown in FIG. 2 (8). In this way, the binary data of the previous scan is stored in the data memory IO in a complete state without any truncation of valid data.

In the embodiment described above, by providing the transfer control unit 13, the processing time for binarization is delayed.

In other words, the effective data is not truncated due to the binarization hard skew, and the effective reading area is prevented from becoming narrower. However, as another embodiment of the present invention, the transfer control unit 13 as described above is used. Instead of providing the transfer enable signal TE, the DMAC 7 may issue the transfer enable signal TE to the data buffer 3 in synchronization with the start of output of the binary data for the current scan from the shift register 12. By doing so, it becomes possible to transfer the binary data for the current scan without truncating effective data, and it is possible to prevent the effective reading area from becoming narrower.

〔Effect of the invention〕

As described above, in the image reading scanner according to the present invention, storage of one scan's worth of binarized data is controlled taking into account the processing time delay due to binarization, so the processing time delay due to the binarization is controlled. This has the excellent effect of preventing the narrowing of the effective kt acquisition area per scan that occurs due to this. Furthermore, since the mJ transfer data block does not include an invalid data area, there is no need to perform window processing to fill the invalid data area with "black J" or "white" pixels.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the image reading scanner according to the present invention, FIG. 2 is a time chart explaining the operation of the image reading scanner shown in FIG. 1, and FIG. 3 is a diagram showing a conventional image reading scanner. FIG. 4, which is a diagram showing an example, is a time chart illustrating the operation of the direct image reading scanner shown in FIG. 2...Binarization unit, 7...DMAC510...Data memory, 14...Memory, 15...Memory control circuit, S-image sensor.

Claims (2)

[Claims] (1) Optical reading means that scans the form surface to be read and outputs video data as a scan result, and binarization that binarizes the video data output from the reading means for each pixel. a processing means, a data storage means for storing the binarized data outputted from the binarization processing means in units of data blocks for each scan, and a processing time delay occurring in the binarization processing means; ,
The memory control means is configured to store the binarized data for one scan in the storage means from the beginning of the data block, and reads out the stored binarized data for one scan at a predetermined timing. An image reading scanner characterized in that it is possible to prevent narrowing of an effective reading area caused by a processing time delay caused by the binarization processing means. (2) The data storage means is configured to store data that has already been written prior to the current scan's worth of binarized data, almost in parallel with the writing of the current scan's worth of binarized data output from the binarization processing means. The binarized data for the previous scan can be read out from the data storage means by the memory control means, and the timing for reading the binarized data for the previous scan from the data storage means is set at a timing corresponding to one scan from the outside. 2. The image reading scanner according to claim 1, wherein the image reading scanner is synchronized with a predetermined transfer timing for the data.