JPH03213858A - Trimming method for image in scanner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for trimming a document during exposure in a plate-making scanner.

(Prior art) In order to print a color original image, it is necessary to create a plurality of separation plates for each specific color of the original image, for example, three or four types. So-called color separation scanners have been used in the past, which perform color separation using electrical signals.

(Problem to be Solved by the Invention) However, with conventional scanners, it is difficult to arbitrarily select only a predetermined portion of the set original image and read and expose the image signal, which is necessary for printing techniques. For trimming, a method has traditionally been adopted in which a trimming mask version is created separately from the separated version created by a scanner, and trimming is performed from the separated version. There was a problem in that it required time and cost.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a method for trimming an image by which a separated version arbitrarily trimmed by a scanner can be immediately obtained.

(Means for Solving the Problems) To achieve this object, the present invention provides a first reading means for reading a document in a wider range than the trimming range in a plate-making scanner that simultaneously reads an image signal and exposes the document. After performing pre-scanning and temporarily storing the read image signal in the image memory, the image signal stored in the image memory is displayed on the monitor, and the trimming range of the image is specified using the coordinate specifying device. storing coordinate data stored in the memory in a memory, then scanning a document set on a scanning drum of a scanner with a second reading means, and generating a gate signal based on the coordinate data stored in the memory; The present invention provides an image trimming method in which the image signal read by the second reading means is sampled in response to this gate signal, and an exposed film in which only the trimming range is color-separated is obtained.

(Function) In the present invention, first, a document is pre-scanned by the first reading means, the obtained image signal is temporarily stored in the image memory, and then displayed on the monitor, and the coordinate specifying means A trimming range is specified on the monitor, and based on this, the second reading means performs main scanning of the document, and outputs a trimmed color-separated image onto an exposed film.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing an embodiment of an apparatus for carrying out the method of the present invention, in which l is a reading scanning drum, 2 is an exposure scanning drum, 3 is a reading head, 4 is an exposure head, 5 is a control device, 6 is a drum drive section, 7 is an image signal processing section, 8 is a film exposure section, 9 is a one-dimensional image sensor, 1o is a lens, 11 is a stepping motor, 12
is a rotary etancoder, 13 is a linear encoder, 14 is a preamplifier, 15 is a peak hold circuit, 16
is an A/D (analog/digital converter), 17 is a bidirectional bus driver, IS is a panzer memory, 19 is an address counter, 20 is an address selector, 21 is a stepping motor driver, 22.23 is a human output controller , 24
25 is an image memory, 25 is a monitor, 26 is a coordinate specifying device, and 27 is a gate. Note that F is the original image to be trimmed.

The reading scanning drum l is intermittently driven at a predetermined period by a stepping motor 11 during pre-trimming scanning to be described later, and is driven at a predetermined period by a drum drive unit 6 together with the exposure scanning drum 2 during reading exposure (hereinafter referred to as main scanning). It rotates at a constant speed at a synchronous speed.

The reading head 3 and the exposure head 4 are driven by a hand drive mechanism (not shown), and are intermittently scanned at predetermined intervals in the direction of the arrow in the figure in synchronization with the rotation of the scanning drums 1 and 2 during main scanning.
Alternatively, the scanning drum 1.can be moved continuously at a predetermined speed.
Scan the surface of 2.

At this time, the image signal S read from the original image F by the reading head 3 becomes an image signal S that has been subjected to predetermined processing in the image signal processing section 7, and a predetermined portion is extracted by the gate 27 to become a trimmed image signal. After S1, the image of an unexposed film (not shown) is supplied to the film exposure section 8 and held on the scanning drum 2 by the exposure head 4, and the exposed film for plate making is color-separated. get. Therefore, the main scanning operation is the same as that of a normal scanner when the gate 27 is open.

-Dimensional image sensor (hereinafter referred to as Is) 9 is a CCD
It comprises a large number of photoelectric conversion elements formed of shape-dimensional solid-state image sensors and the like and arranged in a straight line at a predetermined pitch, and a signal transfer unit that sequentially reads out photoelectric conversion signals from these photoelectric conversion elements in accordance with a clock CK, It functions to obtain an image signal SP by reading image signals line by line from the image of the original/document F projected by the lens IO.

Note that here, the signal Sma is a scan start signal for each line of IS9, and the signal E2 is also an end signal.

The stepping motor 11 is a control bag during pre-scanning! 5 to l
1022, every time reading of the l-line image signal SP by +39 is completed under drive control via the driver 21,
The scanning drum l is rotated by a predetermined rotation angle in the direction of the arrow, and the total th of the original image F by +39! It functions to read image signals over a wide range of areas.

In the above description, the image signal reading scan of one line by +39 is hereinafter referred to as line scanning, and the image signal reading scan due to rotation of the scanning drum 1 is hereinafter referred to as surface scanning.

The rotary encoder 12 functions to detect the rotational angular position of the scanning drum l and to supply a position signal Pv representing it to the control device 5.

The linear encoder 13 serves to detect the position of the reading head 3 and to supply a position signal P representing the position to the control device 5 .

The peak hold circuit 15 receives 1S via the preamplifier 14.
It accepts the image signal SP from 9 and holds the peak value of the image signal S2 in synchronization with the reading clock CM of JS9, so that only the peak value of each pixel of the image signal SP is sent to the A/D 16. Operate as supplied.

The bidirectional bus driver 17 supplies the image signal converted into 4-bit digital data by the A/D 16 to the buffer memory 18, and when the image signal is read from the buffer memory 18, supplies it to the control bag W5. do the work.

The address counter 19 counts the clock CK, operates the address selector 20 based on the count data, and selects one of the image signals to be written into the buffer memory 18.
It functions to specify the address for a line. Note that the address selector 20 also functions to read one line of image data from the buffer memory 18 in response to the read address data RE from the 11J11 device 5.

The image memory 24 functions to accumulate the image signal data read from the buffer memory 18 and to store the image signal data of the entire document F.

The monitor 25 functions to reproduce the image of the original image F based on the image signals stored in the image memory 24.

The coordinate specifying device 26 is equipped with an input operation mechanism such as a keyboard switch and a twist-and-switch, and is used to arbitrarily move the position of a rectangular trimming mark of a preset size that is being reproduced on the image projection surface of the monitor 25 by the control device 5. It functions to generate a position signal PXV.

The gate 27 is an analog gate capable of gating the image signal S, and gates the gate signal G supplied from the control device 5.
The trimming image signal S7 operates in accordance with the image signal T, and has the function of generating a trimmed image signal S7, which is a part of the image signal S, extracted at a predetermined timing.

The control device 5 operates according to various programs incorporated as software or hardware, and is configured to have various data processing functions and control functions for other devices.

Next, the operation of the apparatus shown in FIG. 1 will be explained.

The apparatus shown in FIG. 1 operates in three modes: the pre-trimming scan described above, the subsequent trimming operation, and the main scan for exposing the trimmed image.
First, a document F to be trimmed is set on the operating drum 1, and then pre-trimming scanning is started.

The image of the original F is formed on the photoelectric conversion section of the IS9 by the lens lO. Further, it is held at a position away from the surface of the scanning drum l by a distance determined by the reading magnification of the original F and the focal length of the lens IO.

Therefore, the control device 5 supplies the start signal S and the end signal E11 to +39 in timing synchronization with the clock C11 to perform line scanning, and also supplies the start signal S and the end signal E to +39.
generates a control signal D3 in synchronization with N, drives the stepping motor 11 via the I/D 22 and the driver 21,
The scanning drum l is rotated by a constant angle to perform surface scanning. At this time, the control signal 5 takes in a signal Pv representing the rotational angular position of the scanning drum 1 from the rotary encoder 12, and controls the scanning drum 1 according to a preset document enlargement magnification.
The rotational angular position of is controlled so that the surface is scanned one line at a time using the correct scanning line.

As a result, the image signal SP read out for each pixel of the original F in synchronization with the clock C3 is sequentially extracted from the signal line 139 one line at a time, and this signal SP is passed through the preamplifier 14 to the peak hold circuit 15 After the peak is held for each pixel and digitized by A/D16,
The signal is supplied from the bidirectional bus driver 17 to the buffer memory 18 . At this time, since the write address of the buffer memory 18 is controlled via the address selector 20 by the data of the address counter 19 which receives the clock CK as input, the image signal SP from the ls9 has a different address for each pixel. Thus, the data is taken into the buffer memory 18 one line at a time.

Therefore, every time 1947 worth of image signals are taken into the buffer memory 18, the control device 5 continuously outputs address data R,
is supplied to the address selector 20 and the buffer memory 18
The image signals for one line are read out from the 1 line, processed as a collection of appropriate pixel data according to the document size and exposure magnification set in advance, and then transferred to the image memory 24 via 11023.

Therefore, when the above pre-trimming scan is completed for the entire document F, the image information of the document F is stored in the image memory 24 as a predetermined number (MXN) of pixel data, as shown in FIG. become. In FIG. 2, if P is the pre-trimming scan start point on the surface of the scanning drum l, then this P is the origin, and the line scanning direction by IS9 is also the surface scanning direction by the rotation of the x2 scanning drum l. A coordinate system can be defined as y, and if the number of IS9 photoelectric conversion elements is N, then the number of pixels per line is N, and if the number of scanning lines is M, the total number of pixels is as described above. There will be MXN pieces. Therefore, the position of any pixel data on the image plane read by the pre-trimming scan can be expressed by the scan line number 1 and the pixel number J within each scan line, as shown in FIG. Among them, the number 1 corresponds to the signal Pv obtained from the rotary encoder 12, and the number J corresponds to an arbitrary position of the +39 photoelectric conversion element.

Now, when the pre-trimming scan is completed in this way, the next step is to proceed to the trimming operation, and the control device 5 uses the image memory 24
An image of the document F and a trimming mark of a preset size are displayed on the monitor 25 based on the data read from the monitor 25.

Next, the coordinate specifying device f26 is operated by the operator, and the position signal P is output. By moving the trimming mark on the image projection surface of the monitor 25, trimming is performed on the image surface of the document F obtained by the pre-scanning, and an appropriate trimming range is specified.

This designation is input to the control operation 5 by, for example, a designation completion operation by an operator.

Therefore, the control bag W5 sets the reference point P of the trimming range according to the position signal pHy input at that time.

line number 1. and the pixel number J1, and then the second pixel number J1.
Coordinate values Xt and Yt in the coordinate system shown in the figure are calculated and stored.

When the calculation of this reference point Pt (X?, Yv) is completed, the control device 5 switches to main scanning, and after an unexposed film (not shown) is attached to the scanning drum 2, the drum driving unit 6 starts scanning. The drum 1.2 is driven to rotate at a constant speed, and the image signal S from the reading head 3 is supplied from the image signal processing circuit 7 to the film exposure unit 8 via the gate 27, and the exposure head 4 exposes the trimmed image. The operation at this time will be explained below.

First, for explanation purposes, as shown in Fig. 3, an appropriate origin is set on the surface of the scanning drum 1, and the feeding direction of the rad 3 is set to x1 in the direction opposite to the rotational direction of the scanning drum 1, that is, surface scanning. A coordinate system in which the direction is Y is defined, so that the position of a scanning point on the surface of the scanning drum I can be expressed in XY coordinates.

Then, the X and Y coordinates of this scanning point can be immediately detected using the position signal Px obtained by the linear encoder 13 and the position signal Py from the rotary encoder 12, and the reference point P1 for trimming scanning can be calculated. .

However, since the IS9 is often used in a fixed state, the origin D of the scanning drum l does not coincide with the origin P of the previous scanning machine. P is the origin, offset (Xs, Y*
), therefore, the reference point P for trimming
, in the XY coordinate system (X?, Yv). Therefore, when scanning before trimming, the position coordinates (X@, Y@) of the origin P in the XY coordinate system are set in advance.
is obtained from the position signals P and Pv and stored in the control device 5, it is possible to easily calculate the reference point Pv using the equation (2).

Therefore, when the control device 5 starts main scanning, it detects this reference point P7 and generates a gate signal GT, and the gate 27
is operated at a predetermined timing, extracts a part of the image signal S, extracts a trimmed image signal S7, and exposes it to the unexposed film using the exposure radar 4, so that the trimmed separated plate is immediately exposed. The operation at this time will be explained with reference to timing charts shown in FIGS. 3 and 4.

In Fig. 3, the scanned portion of the document F before trimming is
, the range specified by the trimming mark, that is, the trimming part, is F? and the trimming size is dx, dy
shall be. It is assumed that the document F has no pattern except for the pre-trimming scan area F.

Then, the image signal S obtained by main scanning this has a waveform as shown in FIG. 4, for example. In addition, in this Figure 4,
L is the period required for one rotation of the scanning drum l, that is, l
This is the scan line period.

In this state, when the control device 5 detects the reference point P7 as described above, at that time, it sends a pulse having a width equal to the time Tdy required for the scanning point to move by the distance Mdy from the point P7 for one scanning line period. Gate signal G? The scanning point for generating this pulse is the reference point P? It is repeated for a time equal to the time Tdx for moving by a distance jlldx in the X direction from .

As a result, the gate 27 turns on every time a pulse of the gate signal Gv appears and allows the image signal S to pass through, and a trimmed image signal S7, a part of which is extracted at a predetermined timing.
The unexposed film on the scanning drum 2 is directly exposed to the trimmed image.

The exposure state of the scanning drum 2 to the unexposed film when the gate 27 is off may be arbitrarily determined depending on the trimming plate creation conditions.
For example, it may be left unexposed or completely exposed.

Therefore, according to the above embodiment, arbitrary trimming is possible in the color separation operation by the scanner, and only the trimmed portion can be exposed immediately, and the image signal reading operation by the pre-trimming scan is performed by IS9, which has an extremely fast scanning speed. Since the scanning is completed by line scanning and surface scanning by only one rotation of the scanning drum l within one rotation, the time required for pre-scanning can be sufficiently shortened.

Incidentally, in this embodiment, the image signal obtained in the pre-trimming scan is reproduced on the monitor 25, and if the pixel density of the reproduced image is low, the accuracy of trimming will also be reduced.

However, for example, if 512 photoelectric conversion elements, which have a relatively small number of photoelectric conversion elements, are used as 139, then 10c
When scanning a m x 8 cm original, the error in the trimming range allowed when the exposure magnification is 100% is ±0 because the resolution pitch of I39 is approximately 0.2 mm.
．． It is within 1- or less, and can maintain sufficient accuracy for practical purposes.

In addition, when scanning the short side of an A4 size (210x297) parallel to the rotation axis of the scanning drum l using the same seal S9, the resolution pitch of 139 is approximately 0.41cm, and therefore the error in the trimming range is ± It is within 0.205 m, and sufficient accuracy can be obtained even in this case.

On the other hand, since a black and white monitor is sufficient as the monitor 25, the storage capacity required for the image memory 24 is the same as that of the monitor 25.
When the total number of pixels of the image to be reproduced is set to 512 x 512, it is sufficient to use 3 bits for 8 gradations for the picture and 1 bit for the trimming mark for each pixel.
In total, 128 KB is sufficient, so it is not necessary to use a storage capacity that is too large.

In addition, in the apparatus shown in FIG.
It is configured so that trimming can be performed with a normal plate-making scanner equipped with However, in the present invention, only this pre-trimming scanning mechanism may be constructed as a dedicated device.

However, in such an embodiment that uses a dedicated device, pre-trimming scanning and main scanning are performed by separate devices, so a rotary encoder is required to detect any point on the scanning drum. A front and rear encoder is also required for each device, and it is also necessary to store other data such as the correspondence of scanning positions between both devices in the control device of the device that performs main scanning. However, since the pre-trimming scan and the main scan can be performed independently, flexibility can be given to the plate-making work.

(Effects of the Invention) In the present invention, first, a document is pre-scanned by the first reading means, the obtained image signal is temporarily stored in the image memory and then displayed on the monitor, and the coordinate specifying means The trimming range can be specified on the monitor, and based on this, the second reading means can main scan the document and output the cropped color-separated image onto the exposed film, which eliminates the conventional process. There is no need to create a mask version when trimming the separated version of a color original as in
The amount of mask film used in plate-making work is reduced, and it also helps speed up the work, and compared to trimming using a layout scanner system, the present invention makes trimming easier and more convenient. Since the system does not require a large-scale configuration, it has the advantage of being inexpensive.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the apparatus for carrying out the method of the present invention, FIG. 2 is a schematic diagram showing sampling points in the pre-scanning portion of a document, and FIG. 3 is a schematic diagram of the document on the scanning drum. Schematic diagram showing a pre-scanning part and a trimming part of
The figure is a timing chart showing the relationship between the image signal, the trimmed image signal, and the gate signal. 1, 2 - - - Scanning drum 3 - - - - Reading head 4 - - Exposure head 5 - - - Control device 6
-One drum drive unit 7-...-Image signal processing unit 8--
Film exposure section 9 --- One-dimensional image sensor (IS) to ---
1---Lens 11---Stepping motor 12
・----Rotary encoder 13...--Linear encoder 1 t--
----Preamplifier 15---1.-Peak hold circuit 16---A/D (Analog-to-digital converter) 17--Bidirectional bus driver 18--
...--Buffer memory 19--Address counter 20--Address selector 21--Stepping motor driver 22.23
...--Ilo (input/output controller) 24----1-
-Image memory 25-------Monitor 26-
・・−・−・−Coordinate designation device 27−−−−−−
--Gate Figure 2 Figure 3

Claims (1)

[Claims] In a plate-making scanner that simultaneously reads and exposes an image signal, a first reading means pre-scans an area wider than the trimming range of the original, and the read image signal is once scanned. After storing the image signal in the image memory, display the image signal stored in the image memory on the monitor, specify the cropping range of the image using the coordinate specifying device, store the specified coordinate data in the memory, and then send the image signal to the scanner. The second reading means scans the original set on the scanning drum of the scanner, generates a gate signal based on the coordinate data stored in the memory, and uses this gate signal to cause the second reading means to read the document. 1. A method for trimming an image in a scanner, the method comprising: extracting an image signal from a scanner to obtain an exposed film in which only the trimming range is color-separated.