JP2857937B2 - Planar scanning type image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plane scanning type image reading apparatus used as a so-called plate making scanner for performing printing plate making.

[0002]

2. Description of the Related Art In a plate making scanner, it is necessary to trim a predetermined area in a document in order to read only a desired image area or to designate an analysis area in an automatic setup function. Trimming is
Usually, it is performed by one of the following two methods.

[0003] The first method is a method using a preparation device separate from the scanner. That is, the operator sets a document at a designated position of the preparation device and designates a trimming area. Thereafter, the original is set at a designated position on the table of the scanner. Then, when the preparation device transmits the document frame coordinate data together with the trimming coordinate data to the scanner, the scanner scans and reads the image of the trimming area based on the various information. The trimming frame defines the boundary of the trimming area. Further, as the preparation device, for example, a coordinate input device (digitizer) can be cited.

[0004] A second method is a method using a visual recognition system. That is, a document is pre-scanned by a scanner, the pre-scanned image is displayed on a monitor, and an operator designates an area while looking at the displayed image.
This is a method of performing trimming by obtaining the specified information.

[0005]

However, in the above method, the trimming area of the original in the scanner is set on the table of the scanner because the trimming area of the original is determined based on the trimming coordinate data and the original frame coordinate data. The document also has a drawback that the work efficiency is reduced because it is required to accurately set the document at a designated position, such as aligning one side of the document with the reference line of the table. On the other hand, the method of (1) does not cause a reduction in work efficiency as in the method of (2), but has the disadvantage that the cost is increased due to the provision of the visual recognition system.

The present invention has been made in view of the above circumstances, and provides a flat-scanning image reading apparatus which does not require a highly accurate setting operation when setting a document on a document table of a scanner without a visual recognition system. With the goal.

[0007]

According to a first aspect of the present invention, there is provided a flat-scanning image reading apparatus, comprising: trimming coordinate data and document frame coordinate data of a document input on a preparation device and associated with the same coordinates; Means for receiving coordinate data, a platen on which a document is placed, and a document on the platen.
A prescan means for obtaining image data by pre-scanning at a lower resolution than the scanning, the image data obtained by prescan unit binarized is compared with a predetermined threshold value, the original frame on platen Document frame coordinate calculating means for calculating coordinate data;
A document frame coordinate data from the calculating means, the three parties of the original frame coordinate data and the trimming coordinates data obtained from previous preparation device, and a trimming frame calculation means for calculating a trimming frame in a document on the platen, the Trimming frame calculation means
Scans the original in the trimming frame calculated by
And main scanning means for obtaining data .

Further, Claim second term invention plane scanning image reading apparatus according to of a rotation controllable platen on which an original is placed, pre an original on the platen at a lower resolution than the scanning
A prescan means for obtaining image data by Bei scanned, the image data obtained by prescan unit binarized is compared with a predetermined threshold value, the original frame for calculating the original frame coordinate data on the document table Coordinate calculating means, document tilt amount calculating means for calculating a tilt amount of the document with respect to the scanning direction based on the document frame coordinate data obtained from the calculating means, and a document table rotation for driving the document table based on the tilt amount Means, a trimming frame calculating means for obtaining a position inside the document frame by a predetermined amount as a trimming frame, and a trimming frame calculating means.
The original within the calculated trimming frame is fully scanned and image data is scanned.
And main scanning means for obtaining data .

[0009]

According to the first aspect of the present invention, the original placed on the original platen is scanned by the scanning means and binarized by the original frame coordinate calculating means, whereby the original frame coordinates are automatically set. Is determined. Then, the trimming frame calculating means calculates the trimming frame on the document table from the document frame coordinate data input by the preparation device, the trimming coordinate data, and the document frame coordinate data obtained by the document frame coordinate calculating means. .
Therefore, even if the document is not placed on the document table with high accuracy as in the related art, the tomming frame of the document on the document table can be accurately known.

According to the second aspect, the scanning means and the document frame coordinate calculating means automatically determine the document frame on the document table. The document table is rotated by the document tilt amount calculating means and the document table rotating means. The trimming frame calculating means determines a position inside the document frame of the document by a predetermined amount as a trimming frame. Therefore, in this case, even if the document is not accurately placed on the document table, the position inside the document frame by a predetermined amount is automatically set as the trimming frame, and the trimming frame is set at an arbitrary angle with respect to the scanning direction. Set automatically.

[0011]

(Embodiment 1) An embodiment of the first aspect of the present invention will be described with reference to FIGS. FIG. 1 shows the overall configuration. In FIG.
And a turntable 3 rotatably provided thereon. This rotary table 3
The original 4 is placed on the top.

The scanning means 5 includes a light source (not shown) provided below the base 2, a CCD line sensor 6 for receiving light transmitted through the original 4, and a scanning means 5 interposed between the light source and the line sensor 6. Optical lens system 7. Scanning means 5
, An output circuit for sampling and holding image data and performing A / D conversion, an image processing circuit 9, a bidirectional bus buffer 10, an image memory 11, and a control device 1.
2. The host system 13, the color operation circuit 14, and the halftone signal generation circuit 15 are connected in the order shown.

As will be understood from the following description, the control device 1
Reference numeral 2 has a function of a document frame coordinate calculating means for obtaining document frame coordinates of the document. Further, the host system 13 functions as a calculation unit that calculates a trimming frame of the document and obtains the amount of inclination of the document. A rack portion 2a is formed at one edge portion of the lower surface of the base 2, and a pinion 16a of the sub-scan feed motor 16 meshes with the rack portion 2a to transmit the driving force of the motor 16. Thus, the base 2 is reciprocated in the sub-scanning direction P. The sub-scanning feed motor 16 is provided in a fixed state on a body not shown.

The rotary table 3 has an annular rack portion 3a formed on the peripheral side surface thereof, and the pinion 17a of the rotary drive motor 17 meshes with the annular rack portion 3a.
7, the rotary table 3 is driven to rotate by a required angle. CCD
The line sensor 6 includes a photodiode group in a line shape in the main scanning direction S and a shift register. When the transmitted light guided by the optical lens system 7 is incident on the photodiode group, the photodiode group accumulates optical signal charges corresponding to the incident light, and the optical signal charges are stored in the shift register at a predetermined timing. Will be transferred. The shift register sequentially outputs image data based on the optical signal charges based on a predetermined clock output from the control device 12.

The pre-circuit 8 receives image data output from the CCD line sensor 6, converts the image data into digital data, and outputs the digital data to the image processing device 9. The image processing device 9
The digital image data output from the prefix circuit 8 is subjected to predetermined processing, for example, processing such as shading correction, and is output.

The image data A is obtained by the main scan of the original 4 and is used as color separation information, and is output to the halftone signal generation circuit 15 via the color operation circuit 14. On the other hand, the image data B is obtained by pre-scanning the document 4 and is used as information for document frame detection, and has been subjected to a thinning process. The image data B is output to the image memory 11 via the bidirectional bus buffer 10.

The bidirectional bus buffer 10 opens the bus in the direction of sending the image data B to the image memory 11 at the time of pre-scanning the document 4, while being stored in the image memory 11 at the time of document frame detection processing and automatic setup. The bus is opened in a direction to send the image data B to the control device 12. The control device 12 performs document frame detection processing during pre-scanning and supplies document frame coordinates to the host system 13, and also controls the CCD based on the final trimming frame data and angle data given from the host system 13.
It performs drive control of the line sensor 6, transmission of signals such as an image clock to the image processing device 9, drive control of the rotary drive motor 17, and drive control of the sub-scan feed motor 16.

The host system 13 holds original setup data, trimming coordinate data, and original frame coordinate data sent from a digitizer as a preparatory device through a signal line 18.
And the final trimming frame data and angle data required at the time of the main scan are calculated based on the document frame coordinates sent from the controller and output to the control device 12.

Next, a description will be given of a document frame detection process performed by the controller 12. Assume that the image data B obtained by the prescan corresponds to, for example, seven scanning lines 1 to 7 picked up at predetermined intervals in the sub-scanning direction, as shown in FIG. Looking at the image data for one of the seven scanning lines, for example, the results shown in the graph of FIG. 3 are obtained. The horizontal axis of this graph indicates the pixel address in the main scanning direction, and the vertical axis indicates the level of the image data. As is clear from the graph, the level of the image data of the portion corresponding to the document 4 changes in accordance with the image of the document 4, while the level of the image data of the portion corresponding to the non-document 4 Document holder 3
In order to correspond to the glass part of b, it has a substantially constant value at a high level (a value close to the white level).

Here, it has a value close to the white level, and
A value that is not affected by noise, for example, a white level of 90 to
By performing binarization processing on the image data using the value of 98% as a threshold value, the contour points of the document 4 can be determined. The binarization circuit 12a is incorporated in the control device 12 for binarization. If the contour points are plotted in a coordinate system on a scanner in which the Y coordinate is the main scanning direction S and the X coordinate is the sub-scanning direction P as shown in FIG. Coordinates E ', F', G ',
H ′ is obtained.

These document frame coordinates are stored in the host system 13.
Is forwarded to In the host system 13, the control device 12
The final trimming frame data and angle data required at the time of the main scan are calculated based on the original frame coordinates obtained in step (1), the trimming coordinates of the original sent from the preparation device, and the original frame coordinates. FIG. 6 is a flowchart showing the processing performed by the host system 13. First, necessary coordinate data is received from the digitizer (# 1). From the received data, the host system 13 determines that the positional relationship between the original frame and the trimming frame is, for example, a rectangular frame having coordinates E, F, G, and H as vertices, as shown in FIG. It is known that the trimming frame is represented by a rectangular frame having the coordinates A, B, C, and D as vertices.

Next, the control device 12 performs prescanning of the document and calculation of the document frame coordinates (# 2). The document frame coordinates obtained by the prescan are received from the control device 12 (# 3). FIG. 5B shows the document frame coordinates received from the control device 12. However, actually, the four corners E 'of the original,
Only the coordinate data of F ', G', H 'will be received.

If the document frame coordinates have been received and the necessary data has already been received from the digitizer, the process proceeds to step # 4. Here, first, the document frame coordinates E received in # 1,
Based on the positional relationship between F, G, H and the trimming coordinates A, B, C, D and the original frame coordinates E ', F', G ', H' obtained in # 3, the trimming coordinates required for the main scan. A ',
Find B ', C', D '. These coordinates A ', B',
A trimming frame is defined by C 'and D'. Then, the inclination amount θ of the trimming frame with respect to the main scanning direction S is obtained.

When the inclination amount θ of the trimming frame with respect to the scanning direction is obtained as described above, the obtained value is given to the control device 12. Then, the control device 12 drives the rotation drive motor 17 through the control line 19 and rotates the turntable 3 including the document holder 3b counterclockwise by θ (# 5). As a result, one side of the trimming frame of the document on the document table is set in parallel with the main scanning direction of the scanner. FIG. 5 (c)
Indicates a state rotated by θ in the counterclockwise direction as described above. From the figure, it is understood that the main scanning direction S and one side A'B 'of the trimming frame are parallel.

In the above embodiment, the rotary table 3 is rotated so that one side of the trimming frame is parallel to the main scanning direction. However, one side of the trimming frame is set at an arbitrary angle with respect to the main scanning direction. You can also. in this case,
A desired angle is input in advance from an instruction means such as a keyboard, and a difference between the desired angle and the angle θ is obtained.
What is necessary is just to rotate the turntable by the difference.

Further, in the above embodiment, the original and the trimming frame are square, and the coordinate data of each square is used. However, in the case of the square, the coordinate data of at least two points may be specified. The present invention can be applied to any shape. Also, in FIG. 2 and FIG.
Although the document 4 is shown with a border,
This is provided to reliably perform the binarization process performed when determining the contour points of the document 4, and is not always necessary.

Further, in the embodiment, the document table is provided with a rotary table, but the rotary table is not always necessary in the embodiment of the first aspect of the present invention. Second Embodiment Next, one embodiment of the second aspect of the present invention will be described with reference to FIGS.
It will be described based on. This embodiment shows a case where the operator inputs document frame coordinate data and trimming coordinate data using the preparatory apparatus and obtains a trimming frame on the document table based on the input data. On the other hand, the document frame is determined by pre-scanning without using the preparation device, and the position inside the document frame by a predetermined amount is recognized as the trimming frame. In the present embodiment,
For example, it is suitably used when trimming only the image portion of a document with a fixed width border.

The flat-scanning image reading apparatus according to this embodiment has almost the same configuration as the above-described embodiment.
Further, the document frame detection process performed by the control device 12 is the same as that of the above-described embodiment, and a description thereof will be omitted. FIG.
The operation performed by the host system 13 and the control device 12
5 is a flowchart of the entire image reading apparatus including both operations performed by the image reading apparatus.

First, when a pre-scan mode switch (not shown) is pressed while a document is placed on a document table, pre-scan is performed (# 11), and the read image data B is stored in the image memory 11. (# 1
2). Then, a document frame is extracted using the stored data (# 13), and a calculation of a trimming frame is performed (# 14).

FIG. 9A is a diagram in which the original frame data extracted in # 13 is extracted in a coordinate system in which the main scanning direction is Y and the sub-scanning direction is X. The calculation of the trimming frame is processed in detail according to the flow of FIG. That is, first, from the document frame data obtained in # 13, an inclination angle β of the document with respect to the main scanning direction S (clockwise is defined as positive) is obtained (# 21).
The rotation table and the document frame data are rotated counterclockwise by this tilt angle β (# 22). As a result, FIG.
As shown in (b), one side E '', F '' of the original frame is set parallel to the main scanning direction S. Thereafter, in an orthogonal coordinate system having the main scanning direction S and the sub-scanning direction P as axes shown in FIG. 9C, trimming frames A ", B", C " , D '' are set, and the coordinates of each side are obtained. This coordinate is obtained by adding + t or -t to each side of the document frame in the main scanning direction or the sub-scanning direction, as indicated by # 23.

With the above processing, the trimming frame of the document on the document table can be set in parallel with the main scanning direction. The degree to which the trimming frame is set inside the original frame can be determined as appropriate depending on the type of the original image and the like. However, according to the experience of the present inventor, it is preferable to set the trimming frame to about 3 mm. However, if the document is bordered, it is also possible to electrically detect the width of the line, set this value as t, and obtain a trimming frame. In this way, the trimming frame can be accurately set in the true image area excluding the border. As a method of electrically detecting the border width, a high density threshold is set so that only a high density edge can be extracted from image data read by a CCD line sensor. There is a method of obtaining the width of the image data area.

Processing # 21 to # in FIG. 8 of the above embodiment
The order of 23 may be changed. That is, a trimming frame is set inside by a predetermined amount t from the document frame, and then the inclination angle β
May be rotated. Further, similarly to the first embodiment, the rotation table can be controlled so that the document frame is at an arbitrary angle with respect to the scanning direction.

Further, as the data of the predetermined amount t, a plurality of different data may be stored in advance, and the data may be selected by a pointing means such as a keyboard at the time of scanning according to the document.

[0034]

As described above, according to the first aspect of the present invention, document frame coordinate data of a document placed on a document table is extracted, and this data and document frame coordinate data obtained from a preparatory device are extracted. Since the trimming frame of the document on the document table is obtained from the trimming coordinate data, the operator can accurately know the trimming frame of the document without placing the document on the document table with high accuracy.

In addition, an expensive visual recognition system is not required, and the cost of the apparatus can be reduced. According to the invention of claim 2,
The original frame of the original placed on the original plate is extracted, and the original plate can be arbitrarily set in the scanning direction by rotating the original plate based on the inclination amount of the original frame. In addition, since the trimming frame is obtained by calculating a predetermined amount inside the document frame as a trimming frame, the trimming frame of the document on the document table can be automatically obtained even if the document is not accurately placed on the document table. The efficiency of the document setting work can be improved.

Further, since no visual recognition system is used, an inexpensive device can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a flat-scanning image reading apparatus as one embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating document scanning in pre-scanning.

FIG. 3 is a graph showing a relationship between a pixel address in the main scanning direction for one line and an image data level.

FIG. 4 is an explanatory diagram showing contour points and a document frame of an extracted document.

FIG. 5 is an explanatory diagram showing a document setting state on a preparation device and a document frame extraction and document rotation operation when a document is set out of alignment with a scanner;

FIG. 6 is a flowchart showing an operation of the host system.

FIG. 7 is a diagram for explaining the operation of the device of the second embodiment.

FIG. 8 is a diagram for explaining the operation of the device of the second embodiment.

FIG. 9 is an explanatory diagram showing a trimming frame extraction and document rotating operation when a document is set out of position with a scanner.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 platen 3 rotating table 4 document 6 CCD line sensor 10 bidirectional bus buffer 11 image memory 12 controller 12a binarization circuit 13 host system

Continuation of the front page (56) References JP-A-2-111158 (JP, A) JP-A-3-240359 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 1 / 04-1/207 H04N 1/38

Claims (2)

(57) [Claims] 1. An apparatus which is inputted on a pre-preparation device and which is related with the same coordinates.
Coordinate data receiving means for receiving the trimming coordinate data and document frame coordinate data of the linked document, a document table on which the document is placed, and an image obtained by pre- scanning the document on the document table at a resolution lower than the main scanning. a prescan unit to obtain data, processes give two image data is compared with a predetermined threshold value digitized by the pre-scanning means, a document frame coordinate calculating means for calculating a document frame coordinate data on the document table, a document frame coordinate data from the calculating means, the three parties of the original frame coordinate data and the trimming coordinates data obtained from previous preparation device, and a trimming frame calculation means for calculating a trimming frame in a document on the platen, the Trimming calculated by trimming frame calculation means
Main scanning means for obtaining image data by performing main scanning of the original in the frame
And a flat-scanning image reading apparatus. 2. A rotary controllable platen on which an original is placed, a preliminary scanning means for obtaining an image data of the document on the platen by prescanning at a lower resolution than the scanning, resulting in pre-scanning means The original image data is compared with a predetermined threshold value to perform binarization processing, and original frame coordinate calculating means for calculating original frame coordinate data on the original platen. Based on the original frame coordinate data obtained from this calculating means, Document tilt amount calculating means for calculating the tilt amount of the document with respect to the scanning direction; platen rotating means for driving the platen to rotate based on the tilt amount; and a position inside the document frame of the document by a predetermined amount as a trimming frame. Trimming frame calculating means to be obtained and trimming calculated by the trimming frame calculating means
Main scanning means for obtaining image data by performing main scanning of the original in the frame
And a flat-scanning image reading apparatus.