JPH0698112A - Plane scanning image reader - Google Patents

Abstract

PURPOSE:To improve the efficiency of setting by unnecessitating the accurate setting of an original in the case of setting the original to a scanner. CONSTITUTION:An original 4 set on a rotary table 3 is prescanned, image data are provided and binarized by a controller 12 so as to extract the contour of the original, and a trimming frame to the original on the rotary table 3 is judged by this contour, triming coordinate and original frame coordinate. Therefore, it is not necessary to accurately set the original on an original platen, and the efficiency of original setting can be improved. Further, the cost can be reduced since it is not necessary to provide any visual confirmation system.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In a plate-making scanner, trimming a predetermined area in a document is necessary for reading only a desired image area or for designating an analysis area in an automatic setup function. Trimming
Usually, it is performed by either of the following two methods.

The first method is a method using a preparation device separate from the scanner. That is, the operator sets the original at the designated position of the preparation device and designates the trimming area. After that, the above document is set at a designated position on the table of the scanner. Then, when the preparation apparatus 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 these various information. The trimming frame defines the boundary of the trimming area. As the preparatory device, for example, a coordinate input device (digitizer) can be cited.

The second method is a method using a visual recognition system. That is, the scanner prescans the original, displays the prescan image on the monitor, and the operator designates the area while watching the displayed image.
This is the method of obtaining the designation information and performing the trimming.

[0005]

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

In view of the above circumstances, the present invention provides a plane scanning type image reading apparatus which does not require a highly accurate setting operation when setting a document on a document table of a scanner without equipping a visual recognition system. With the goal.

[0007]

According to a first aspect of the present invention, there is provided a plane scanning type image reading apparatus which receives coordinate data and trimming coordinate data of an original inputted on a preparatory apparatus. A document table on which a document is placed, a scanning unit that scans the document on the document table to obtain image data, and the image data obtained by the scanning unit is compared with a predetermined threshold value to perform binarization processing. The document frame coordinate calculating means for calculating the document frame coordinate data on the document table, the document frame coordinate data obtained from this calculating means, and the document frame coordinate data and the trimming coordinate data obtained from the preparatory device. A trimming frame calculating means for calculating a trimming frame in the original on the original table is provided.

According to a second aspect of the present invention, there is provided a plane scanning type image reading apparatus in which a rotation-controllable document table on which a document is placed and a document on the document table are scanned to obtain image data. Means and a document frame coordinate calculating means for comparing the image data obtained by the scanning means with a predetermined threshold value to perform binarization processing and calculating document frame coordinate data on the document table. A document tilt amount calculation means for calculating the tilt amount of the document with respect to the scanning direction based on the document frame coordinate data, a document table rotating means for rotationally driving the document table based on the tilt amount, and a predetermined amount more than the document frame of the document. A trimming frame calculating means for obtaining an inner position as a trimming frame is provided.

[0009]

According to the structure of the first aspect, the document placed on the document table is scanned by the scanning means and binarized by the document frame coordinate calculating means, whereby the document frame coordinates are automatically determined. Sought. Then, from the document frame coordinate data input by the preparation device, the trimming coordinate data, and the document frame coordinates obtained by the document frame coordinate computing unit, the trimming frame computing unit
The trimming frame on the platen is calculated. Therefore, it is possible to accurately know the tomming frame of the document on the document table without accurately placing the document on the document table as in the conventional case.

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

[0011]

(Embodiment 1) An embodiment of the invention according to claim 1 will be described with reference to FIGS. FIG. 1 shows the overall configuration. In FIG. 1, the document table 1 is shown in the sub-scanning direction P.
It is composed of a base 2 which is movable to the inside and a turntable 3 which is rotatably provided on the base 2. This turntable 3
The original 4 is placed on top.

The scanning means 5 is interposed between 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 line sensor 6 from the light source. And an optical lens system 7 that is formed. Scanning means 5
On the output side of, the pre-circuit 8, which samples and holds the image data and performs A / D conversion, the image processing circuit 9, the bidirectional bus buffer 10, the image memory 11, the control device 1.
2. The host system 13, the color calculation circuit 14, and the halftone dot 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 a document. The host system 13 also functions as a calculation unit that calculates the trimming frame of the document and that calculates the amount of inclination of the document. A rack portion 2a is formed at an edge portion on one side of the lower surface of the base 2, and a pinion 16a of a sub-scan feed motor 16 is meshed with the rack portion 2a to transmit a driving force of the motor 16. As a result, the base 2 is reciprocated in the sub-scanning direction P. The sub-scan feed motor 16 is provided in a fixed state on a machine body (not shown).

An annular rack portion 3a is formed on the peripheral surface of the rotary table 3, and a pinion 17a of a rotary drive motor 17 meshes with the annular rack portion 3a so that the motor 1
By transmitting the driving force of 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 an optical signal charge according to the incident light, and the optical signal charge is stored in the shift register at a predetermined timing. Transferred. Then, the shift register is designed to sequentially output the image data based on the optical signal charges based on a predetermined clock output from the control device 12.

The front-end circuit 8 inputs the image data output from the CCD line sensor 6, converts the image data into a digital amount, and outputs the digital amount to the image processing device 9. The image processing device 9
The digital image data output from the front-end circuit 8 is subjected to predetermined processing, for example, processing such as shading correction, and then output.

The image data A is obtained by the main scan of the original 4 and used as color separation information, and is output to the halftone dot signal generation circuit 15 via the color calculation circuit 14. On the other hand, the image data B is obtained by pre-scanning the original 4 and is used as information for detecting the original frame, and has been thinned out. 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 when the document 4 is pre-scanned, and is stored in the image memory 11 during the document frame detection process and automatic setup. The bus is opened in the direction to send the image data B present 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, based on the final trimming frame data and angle data provided from the host system 13, the CCD.
Drive control of the line sensor 6, transmission of a signal such as an image clock to the image processing device 9, drive control of the rotary drive motor 17, drive control of the sub-scan feed motor 16 and the like are performed.

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

Next, the document frame detection process performed by the controller 12 will be described. It is assumed that the image data B obtained by the pre-scan correspond to, for example, seven scanning lines 1 to 7 picked up at a predetermined interval in the sub scanning direction, as shown in FIG. Looking at the image data for one scanning line out of the seven, for example, the results shown in the graph of FIG. 3 are obtained. The horizontal axis of this graph shows the pixel address in the main scanning direction, and the vertical axis shows the level of image data. As is apparent from the graph, the level of the image data of the portion corresponding to the original 4 changes corresponding to the image of the original 4, while the level of the image data of the portion corresponding to the non-original portion is Document holder 3
In order to correspond to the glass part of b, it has a substantially constant value at a high level (value close to white level).

Here, the value has a value close to the white level, and
A value that is not affected by noise, for example, the white level 90-
By binarizing the image data with a value of 98% as a threshold value, the contour points of the original 4 can be discriminated. The binarization circuit 12a is incorporated in the control device 12 for binarization. If the contour points are plotted in a coordinate system on the 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. 4, the four corners of the original are calculated by approximation calculation based on these contour points. Coordinates E ', F', G ',
H'is obtained.

These document frame coordinates are determined by the host system 13.
Transferred to. In the host system 13, the control device 12
The final trimming frame data and angle data necessary for the main scan are calculated based on the document frame coordinates obtained in step 1, the document trimming coordinates sent from the preparation device, and the document frame coordinates. FIG. 6 is a flowchart showing the processing performed by the host system 13. First, the necessary coordinate data from the digitizer is received (# 1). From the received data, the host system 13 determines that the positional relationship between the document frame and the trimming frame is a rectangular frame having the 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 coordinates A, B, C and D as vertices.

Next, the document prescan and the document frame coordinate calculation are performed on the control device 12 (# 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, in reality, the four corners E ′ of the original,
Only coordinate data of F ', G', H'will be received.

If the original frame coordinates have been received and the necessary data has already been received from the digitizer, the process proceeds to # 4. Here, first, the document frame coordinates E received in # 1,
Trimming coordinates required for the main scan based on the positional relationship between F, G, H and trimming coordinates A, B, C, D and the document frame coordinates E ', F', G ', H'obtained in # 3. A ',
Find B ', C'and D'. These coordinates A ', B',
The 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, it is given to the control device 12. Then, the controller 12 drives the rotary drive motor 17 through the control line 19 to rotate the rotary table 3 including the document holder 3b in the counterclockwise direction by θ (# 5). As a result, one side of the trimming frame of the document on the document table is set parallel to the main scanning direction of the scanner. FIG. 5 (c)
Indicates the 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.

Although the rotary table 3 is rotated so that one side of the trimming frame is parallel to the main scanning direction in the above embodiment, one side of the trimming frame is set at an arbitrary angle with respect to the main scanning direction. You can also do it. in this case,
Input the desired angle in advance from an instruction means such as a keyboard, calculate the difference between this desired angle and the angle θ,
The rotary table may be rotated by the difference.

Further, in the above embodiment, the original and the trimming frame are made square and the coordinate data of each square is used. However, in the case of the square, it is sufficient to specify the coordinate data of at least two points respectively, and other than the square. The present invention can be applied even in the case of a shape. In addition, in FIG. 2 and FIG.
Although the document 4 is shown with a border,
This is provided in order to surely perform the binarization processing performed when the contour points of the original 4 are discriminated, and is not necessarily required.

Further, in the embodiment, the document table is provided with a rotary table, but the rotary table is not always necessary in the practice of the invention of claim 1. (Embodiment 2) Next, an embodiment of the invention of claim 2 will be described.
This will be described with reference to FIGS. 7 to 9. In the present embodiment, the above-described first embodiment shows a case where the operator inputs the document frame coordinate data and the trimming coordinate data with the preparatory apparatus and obtains the trimming frame on the document table based on the input data. On the other hand, without using the front reference device, the document frame is discriminated by the prescan, and the inner position of the document frame by a predetermined amount is recognized as the trimming frame. The apparatus according to the present embodiment is preferably used, for example, in the case of trimming only an image portion of a document having a fixed width.

The plane scanning type image reading apparatus according to this embodiment has substantially the same configuration as the above embodiment,
Further, the document frame detection process performed by the control device 12 is the same as that in the above-mentioned embodiment, and therefore its explanation is omitted. Figure 7
Is an operation performed by the host system 13 and the control device 12
6 is a flowchart of the entire image reading apparatus including both of the operations performed by the above.

First, when a prescan mode switch (not shown) is pressed with a document placed on the document table, prescan is performed (# 11) and the read image data B is stored in the image memory 11. Is stored in (# 1
2). Then, a document frame is extracted using this accumulated data (# 13), and then the trimming frame is calculated (# 14).

FIG. 9A is a drawing in which the document frame data extracted in # 13 is extracted in a coordinate system having Y in the main scanning direction and X in the sub scanning direction. The calculation of the trimming frame is processed in detail by the flow of FIG. That is, first, from the document frame data obtained in # 13, the inclination angle β of the document with respect to the main scanning direction S (clockwise is positive) is determined (# 21),
The rotary table and the document frame data are rotated counterclockwise by this tilt angle β (# 22). As a result,
As shown in (b), one sides E ″ and F ″ of the document frame are set parallel to the main scanning direction S. After that, in the orthogonal coordinate system having the main scanning direction S and the sub-scanning direction P as axes shown in FIG. 9C, the trimming frames A ″, B ″, and C ″ are located inside the document frame by a predetermined amount t. , D ″ are set and the coordinates of each side are obtained. This coordinate is obtained by adding + t or -t in the main scanning direction or the sub scanning direction to each side of the document frame, as shown in # 23.

Through the above processing, the trimming frame of the document on the document table can be set parallel to the main scanning direction. The extent to which the trimming frame is set inside the original frame can be appropriately determined according to the type of the original image, etc., but according to the experience of the present inventor, the trimming frame is preferably set to about 3 mm. However, if the original has been trimmed, the trimming width can be electrically detected, and this value can be set as t to obtain the trimming frame. By doing so, the trimming frame can be accurately set in the true image area excluding the border. As a method of electrically detecting the edging width, a high density threshold value is set so that only a high density edge portion can be extracted from the image data read by the CCD line sensor. There is a method of obtaining the width of the image data area.

Processes # 21 to # in FIG. 8 of the above embodiment
The order of 23 may be changed. That is, a trimming frame is set inward from the document frame by a predetermined amount t, and then the tilt angle β is set.
You may rotate in search of. Further, similarly to the first embodiment, the rotary table can be controlled so that the document frame has 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 may be selected by an instruction 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, the document frame coordinate data of the document placed on the document table is extracted, and the data and the document frame coordinate data obtained from the preparatory device and Since the trimming frame of the document on the platen is obtained from the trimming coordinate data, the trimming frame of the document can be accurately known even if the operator does not place the document on the platen accurately.

In addition, the cost of the apparatus can be reduced without the need for an expensive visual recognition system. According to the invention of claim 2,
The original frame of the original placed on the original table can be extracted, and the original table can be rotated based on the amount of inclination of the original frame to arbitrarily set the original in the scanning direction. Further, since a predetermined amount inside the document frame is used as a trimming frame for calculation, the trimming frame of the document on the document table can be automatically calculated without placing the document on the document table with high precision. The original setting work can be streamlined.

Further, as in the first aspect, since no visual recognition system is used, an inexpensive device can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a plane scanning image reading apparatus as an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating document scanning in prescan.

FIG. 3 is a graph showing a relationship between a main scanning direction pixel address 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 set state on the preparatory device and a document frame extraction and document rotation operation when the document is set to be displaced by the scanner.

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

FIG. 7 is a diagram illustrating an operation of the apparatus according to the second embodiment.

FIG. 8 is a diagram illustrating the operation of the apparatus according to the second embodiment.

FIG. 9 is an explanatory diagram showing a trimming frame extraction operation and a document rotation operation when a document is set on a scanner while being displaced.

[Explanation of symbols]

 1 Manuscript Platen 3 Rotary Table 4 Manuscript 6 CCD Line Sensor 10 Bidirectional Bus Buffer 11 Image Memory 12 Controller 12a Binarization Circuit 13 Host System

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[Procedure amendment]

[Submission date] March 18, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

Further, in the embodiment, the document table is provided with a rotary table, but the rotary table is not always necessary in the practice of the invention of claim 1. (Embodiment 2) Next, an embodiment of the invention of claim 2 will be described.
This will be described with reference to FIGS. 7 to 9. In the present embodiment, the above-described first embodiment shows a case where the operator inputs the document frame coordinate data and the trimming coordinate data with the preparatory apparatus and obtains the trimming frame on the document table based on the input data. On the other hand, without using the preparatory device, the document frame is discriminated by the prescan, and the inner position of the document frame by a predetermined amount is recognized as the trimming frame. The apparatus according to the present embodiment is preferably used, for example, in the case of trimming only an image portion of a document having a fixed width.

Claims (2)

[Claims] 1. A coordinate data receiving means for receiving trimming coordinate data and document frame coordinate data of a document input on a preparatory apparatus, a document table on which a document is placed, and a document on the document table is scanned. Scanning means for obtaining the image data, and manuscript frame coordinate calculation means for calculating the manuscript frame coordinate data on the manuscript table by comparing the image data obtained by the scanning means with a predetermined threshold value to perform binarization processing. Trimming frame calculating means for calculating the trimming frame in the original on the platen from three parts of the document frame coordinate data obtained from the computing means, the document frame coordinate data and the trimming coordinate data obtained from the preparation device. A planar scanning type image reading device characterized in that. 2. A manuscript table on which a manuscript is placed, the rotation of which is controllable, scanning means for scanning the manuscript on the manuscript table to obtain image data, and image data obtained by the scanning means as a predetermined threshold value. A document frame coordinate calculation means for comparing and binarizing the document frame coordinate data on the document table, and a document inclination amount with respect to the scanning direction are calculated based on the document frame coordinate data obtained from this calculation means. An original document inclination amount calculation unit, an original document platen rotation unit that rotationally drives the original document platen based on the inclination amount, and a trimming frame calculation unit that obtains a trimming frame at a position that is a predetermined amount inward of the original document frame. A flatbed scanning image reading device characterized in that