JPH03213857A - Trimming method for image in scanner - Google Patents

Abstract

PURPOSE:To eliminate the need for a mask plate by displaying an image signal on a monitor after storing the signal temporarily in an image memory by prescanning, specifying trimming range by a coordinate specifying means, and scanning the original again and outputting an image which is already trimmed and color-separated on an exposed film. CONSTITUTION:A read means 3 makes a prescan on the original set on a scanning drum 1 within a range larger than the trimming range, the read image signal is stored temporarily in the image memory 19 and then displayed on the monitor 20, and a coordinate specifying device 21 specifies the trimming range of the image and stores specified coordinate data in a memory. Then when the read exposure of the original set on the scanning drum 1 is performed, a gate signal based upon the coordinate data stored in the memory 19 is generated and the image signal read by the read means 3 is sampled to obtain the exposed film whose trimming range only is color-separated. Consequently, a color-separated plate which is trimmed optionally by a scanner is obtained immediately without forming a mask plate for trimming.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for trimming an original image 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 N 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 in printing techniques. In order to perform detailed trimming, the conventional method has been to create a trimming mask version separately from the separated version created by the scanner, and then perform trimming 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 plate-making scanner that simultaneously reads image signals and exposes images, and scans a wider range than the trimming range of a document set on a scanning drum. After performing pre-scanning with the means and temporarily storing the read image signal in the image memory, display the image signal stored in the image memory on the monitor, and specify the trimming range of the image with the coordinate specifying device. The coordinate data stored in the memory is stored in a memory, and then, when a document set on the scanning drum is read and exposed, a gate signal is generated based on the coordinate data stored in the memory, and this gate signal causes the reading means to To provide an image trimming method in a scanner that extracts read image signals and obtains an exposed film in which only the trimming range is color-separated.

(Function) In the present invention, first, an image signal obtained by performing pre-scanning on a document set on a scanning drum is stored in an image memory, and then displayed on a monitor, and a coordinate specifying means is used to By specifying a trimming range on the monitor, the document is scanned again based on this, and a trimmed and color-separated image can be output on 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 implementing the method of the present invention, in which 1 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 clock generation section, 7 is a drum drive section, 8 is a scanning head drive section, 9 is an image signal processing section, IO is a film exposure section, 11 is a preamplifier, 12 is a sample hold circuit, 13 is a A/D (Analog-to-Digital Converter), 14 is a bidirectional bus driver, 15 is Batza memory, 16 is an address counter, 17 is an address selector, 18 is l10 (input/output controller), 19 is an image memory, 20 is Monitor, 21 is coordinate specifying device, 2
2 is a gate, and 23 and 24 are changeover switches. Note that F indicates the manuscript.

The scanning drums 1 and 2 are rotated at a constant speed by a drum driving section 7 at a predetermined synchronous speed.

The reading head 3 and the exposure head 4 are linearly driven by a scanning head drive section 8, and move intermittently or continuously at a predetermined speed in synchronization with the rotation of the scanning drum 1.2, and are wound around the scanning drum l. The image signals are read from the original document F that is being stored, and the image signals are exposed onto a film (not shown) wound around the scanning drum 2.

The control device 5 operates according to a program incorporated as software or hardware, and has various data processing functions and a control function for other devices such as a clock generator 6.

The clock generator 6 operates according to instructions from the control device 5, and functions to generate a scanning head feed clock D11 and a scanning sampling clock C3 having different frequencies depending on scanning conditions.

The image signal processing unit 9 receives the image signal S read by the reading head 3.
It functions to perform the necessary processing.

The film exposure section IO operates the exposure head 4 to perform exposure using the image signal S or S-ma.

Therefore, these scanning drums 1.2, heads 3°4, w
tm device 5, clock generator 6, drum drive section 7, scanning head drive section 8, image signal processing section 9, film exposure section l
O is the same as a normal color separation halftone scanner, and by switching the changeover switches 23 and 24 to the a contact side, the scanner operates as a normal scanner and can obtain the necessary separated plates.

Next, when the changeover switch 23 is switched to the contact side, the sample and hold circuit 12 samples the image signal Sl inputted from the image signal processing section 9 via the preamplifier 11 using the clock C5, holds it, and outputs A/
It functions to supply D13.

The bidirectional bus driver I4 functions to input the output of the A/D 13 to the buffer memory 15 and to send data read from the A/D 13 to the control device 5.

The address counter 16 counts the clock C8 and uses the data to operate the address selector 17 to designate an address in the buffer memory 15.

Here, W is a signal that controls the buffer memory 15 to write data, and is generated during the image signal scanning period during one rotation of the scanning drum 1.2, and R1 specifies the data successive address of the buffer memory 13. Therefore, the buffer memory 15 sequentially inputs the image signal St to a different address for each sampling point during the scanning period. It functions to store data for l scanning lines and input the data to the control device 5 between the end of the scanning period and the beginning of the next scanning period.

The control device 5 converts the manually inputted image data from the buffer memory 15 into a collection of image data suitable for a preset document size and exposure magnification, and transfers it to the image memory 19 via l1018.

The monitor 20 functions to reproduce one frame worth of image data stored in the image memory 19 as a still image in the image projection direction.

The coordinate specifying device 21 is equipped with a manual operation unit such as a keyboard and a twister, and is used to move the position of a rectangular trimming mark of a preset size that is being reproduced on the image projection surface of the monitor 20 by the control device 5 to an arbitrary position. operate,
It functions to generate data P□ representing the coordinates of a predetermined position.

The gate 22 is operated by the gate signal G from the control circuit 5, gates the image signal S, and produces a trimmed image signal S! from which only a predetermined portion of the image signal S! is extracted. It works to extract.

The changeover switches 23 and 24 change the operation of the scanner to the normal disassembly plate creation operation (both switches 23 and 24 are switched to the a contact side).

(2) Scanning before trimming (switch 23 to the b contact side. Note that the switch 24 may be on either contact side).

■Trimming plate creation operation (switch 23 to the a contact side,
Switch 24 is switched to the b contact side).

It functions to select one of the three modes, and may be operated manually or automatically by the control device 5.

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

First, the operation in mode ■ is the same as a normal scanner and has already been explained, so a detailed explanation will be omitted.

When creating a trimmed version of document F, it is necessary to first operate in mode (2), then perform necessary trimming operations, and then operate in mode (2).

Therefore, first, as shown in Fig. 2, the document F is attached to the scanning drum L, and a part that is one size larger than the part F to be trimmed is set, and this is called the pre-scan part F. do.

Next, the mode is controlled to ■, the switch 23 is switched to the b contact side, and reading of the image signal S from the pre-scanning portion F2 of the original F is started by the rotation operation of the scanning drum 1 and the feeding operation of the reading rad 3. . At this time, as shown in Figure 3,
The scanning line and pitch L are determined by the feed pinch of the reading rad 3, that is, the clock D, and the sampling pitch SP is determined by the clock C8.

At this time, in order to read both image signals S from only the pre-scanned portion F of the original F, it is necessary to detect the coordinates Xs and Ye of the scanning start origin P on the surface of the scanning drum L. However, since a normal scanner is equipped with an encoder or the like on the scanning drum 1, and the coordinate Y in the rotational direction can be easily determined, there is no problem.

Since the coordinate X in the X direction is determined by the position of the reading head 3, either a linear position detector is provided on the reading head 3, or a reference point whose position W can be adjusted is provided in the feeding direction. Then, the position of the reading head 3 at the reference point is detected by some means, such as a micro switch or a proximity switch, and then the clock D is counted to determine the position of the reading head 3 in the X direction, that is, the position Il!
All you have to do is find X.

In this way, if the scanning start point P of the pre-scanning portion F is determined, the scanning end position can also be determined in the same way, so that the pre-scanning portion F can be set arbitrarily.

As already explained, the image signal S from the previous scanning portion F is accumulated in the buffer memory 15 every l scanning lines, and then sequentially transferred to and stored in the image memo January 9.

As a result, when the reading scan from the entire area of the previous scanning portion F is completed, one frame worth of image signals corresponding to this portion F will be stored. The image is played.

Therefore, the operator operates the coordinate specifying device 21 to move the position of a rectangular trimming mark of a preset size that is being reproduced on the image projection surface of the monitor 20 together with the image of the pre-scanned portion F, and performs trimming. Match the image of part F. As a result, the control device 5 determines the origin P of this trimming portion F.

The PNV representing the coordinates X,,Y, is manually generated.

Thereby, the control device 5 calculates the coordinate data X1 and Yl of the origin P of the trimming portion F shown in FIG. 2, and stores this and the trimming sizes dx and dy, respectively.

These data x t , Y t + dx, d
When the storage of y is completed, the operation is switched to mode (2) by the control device 5 or the operator, and the switch 23 is closed to the a contact side and the switch 24 is closed to the b contact side. Then, an unexposed film is set on the scanning drum 2, and the operation of the scanner is started.

Next, the operation at this time will be explained with reference to the timing chart of FIG.

In FIG. 4, S is an image signal input from the image signal processing section 9 to the gate 22 via the a contact of the switch 23 and the b contact of the switch 24. G is the image signal supplied to the gate 22 from the control device 5. The gate signal Sv is a trimming image signal extracted from the gate signal G and the biased image signal S at the gate 22 and exposed to the exposure head 4 from the film exposure section 10, and L is the trimming image signal when the scanning drum l rotates once. represents the period of time.

The control device 5 monitors the coordinate Y due to the rotation of the scanning drum 1 and the coordinate X due to the position of the reading rad 3, and further monitors the reading rad 3 based on the captured data Xt, Y, dx, and dy.
A gate signal G7 having a pulse width Tdy is generated at regular intervals from time t when the reading position reaches the origin P7, and this is continued for a period from time t to Tdx. Here, the pulse width Tdy is equal to the time required for the scanning drum l to rotate the distance of the trimming size dy in FIG.
The period Tdχ is equal to the time required for the recording head 3 to move the distance of the trimming size dx, and the control device 5 is informed of the rotational speed of the scanning drum 1, the rotational phase, and the moving speed and position of the scanning drum 3. Since all have been taken in, these and the above data Xv and Yt.

The control device 5 can easily generate the gate signal G7 using dx and dy.

At the gate 22, the image signal S is generated by the gate signal G.
, and the extracted signal S7 is obtained as a trimmed image signal.As can be easily understood by comparing FIG. 2 and FIG. It can be seen that the image signal S7 is only the image signal when the trimmed portion F1 of the original image F is scanned.

Therefore, if the trimming image signal S7 extracted by this gate signal G7 is exposed by the exposure head 4, the trimming portion F? An exposed film in which only the colors have been separated can be obtained directly by a scanner, and according to this embodiment, a trimming plate can be created directly by a scanner.

By the way, in the above explanation, the clock D, 1. Although the frequency of Cs was not specifically explained, these frequencies may be controlled arbitrarily.

Of these, clock D determines the feed speed of the reading head 3, and this allows the scanning line pitch L7 shown in FIG. 3 to be changed, so by increasing the frequency of clocks D and I, The time required to scan the entire scanning portion F and store data for one frame in the image memory 19 can be shortened.

Further, the clock C8 determines the sampling points P of the image shown in FIG. 3, and the higher its frequency, the smaller the sampling pitch SP becomes (the more the number of sampling points P per scanning line increases).

Since the sampling point P, that is, the number of pixels in the entire pre-scanning portion F0, is determined by the scanning line pitch LP and the sampling pitch SP, the storage capacity required for the image memory 19 is determined by the frequency of the clocks DH and C8. That will happen. Therefore, increase the frequency of clock D,
If you lower the frequency of clock C1, image memory 1
9 storage capacity can be reduced.

On the other hand, in the embodiment described above, the image signal obtained by the pre-scanning is reproduced on the monitor 20, and trimming is performed on the reproduced screen, so that if the pixel density of the reproduced image is coarse, the accuracy of trimming decreases.

Therefore, clock D. The frequency of and CS may be set by taking into consideration the time required for pre-trimming scanning, the storage capacity required for the image memory 19, the trimming accuracy, etc.

For example, in the above example, 10cmX8Cl (Xx
When scanning the document y) at an exposure magnification of 100%, if the number of scanning lines in the previous scan is 50 lines and 7 cm, the scanning line pitch is 0.
．． 2-, so the error in the trimming range is within ±0.1 degrees, and in this case, sufficient accuracy can be obtained to determine the trimming range on the original. However, under conditions where the exposure magnification is larger than this, , Since the deviation of the trimming range on the film to be exposed becomes large, the number of scanning lines during the pre-scanning is increased in accordance with the exposure magnification, and the feed clock D is set so that the sampling pitch is fine.

The frequency of the sampling clock C8 and the frequency of the sampling clock C8 may be adjusted by the control device 5.

Furthermore, since it is sufficient to use a black and white monitor 20 as a display for displaying pre-scanned images, if we consider a 512 x 512 pixel image memory to be used, each pixel has 8 gradations for the picture. Assuming that 3 bits are taken and 1 bit is taken for displaying the trimming mark, a total of 128 KB of image memory 19 may be used.

Note that in the above embodiment, the buffer memory 15 is a Songle one, but if the target scanner is a high-speed one, the buffer memory 15 is made into a double buffer, and image data is written and read out. You can do it in parallel.

(Effects of the Invention) In the present invention, first, an image signal obtained by performing pre-scanning on a document set on a scanning drum is stored in an image memory and then displayed on a monitor. This allows you to specify the trimming range on the monitor, scan the original again based on this, and output the cropped, color-separated image onto exposed film. Since there is no need to create a mask plate when trimming separated plates, the amount of mask film used in plate-making work is reduced, and it also helps speed up the work, compared to trimming using a layout scanner system. Then, the present invention has the advantage that trimming can be performed more easily and simply, and the system configuration does not require a large-scale system, so it can be done at low cost. Because the functions of a normal scanner can be used as is, there is no need for special dedicated equipment for pre-scanning, and the excellent effect is that a trimming mechanism can be incorporated into a conventional scanner for relatively easy items. play.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an apparatus for carrying out the method of the present invention, FIG. 2 is a schematic diagram showing a pre-scanning portion and a trimming portion of a document on a scanning drum, and FIG. Schematic diagram showing sampling points in the pre-scanning part, No. 4
The figure is a timing chart showing the relationship between the image signal, the trimmed image signal, and the gate signal. l, 2--1111 Scanning drum 3--Reading head 4--Exposure head 5--Control device 11--Preamplifier 12-- ---Sample hold circuit 13...--A/D (Analog-to-digital converter) 1
4...---1---Bidirectional bus driver 15---
--Buffer memory 16--Address counter 17--
-Address selector 18...-l10 (input/output controller) 19...-Image memory 20
-------Monitor 21-----One coordinate designation device 22--Gate 23.24--
- Selector switch Figure 2 Figure p Target

Claims (1)

[Claims] In a plate-making scanner that simultaneously reads image signals and exposes images, a document mounted on a scanning drum is pre-scanned by a reading means over an area wider than the trimming area, and the read image is read. After storing the signal in the image memory,
The image signal stored in the image memory is displayed on a monitor, the trimming range of the image is specified by the coordinate specifying device, the specified coordinate data is stored in the memory, and then the document set on the scanning drum is At the time of reading exposure, a gate signal is generated based on the coordinate data stored in the memory, and the image signal read by the reading means is extracted by this gate signal, and the exposed film is color-separated only in the trimming range. A method for cropping an image in a scanner, characterized in that: