JPH10336428A - Image processing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the image processing unit by which trimming is conducted automatically and quickly. SOLUTION: Rectangular image originals 12a-12e placed on an original platen 11 are read with accuracy rougher than that of the main scanning and preliminary scanning image data are acquired. The plural sampling points 6 are set for the preliminary scanning image data. The sampling points 6 are placed at a rougher interval than a pixel interval of the preliminary scanning image data. Then sampling points (marked white rounds) on the image originals are extracted among plural the set sampling points, and one sampling point is selected among the extracted sampling points. Then the selected sampling point is used for a start point to trace a contour of the image original, then a coordinate of each apex of the image original is detected. Then based on the detected apex coordinate, a trimming frame with respect to the image original is defined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly, to a method of reading an image manuscript with a coarser accuracy than a main scan to obtain prescan image data, and using the prescan image data. The present invention relates to an image processing apparatus for setting a trimming area during a main scan. Furthermore, the present invention is also directed to a recording medium storing program data to be executed by the image processing apparatus and a method for providing the program data.

[0002]

2. Description of the Related Art With rapid progress of electronic technology in recent years, image processing using a computer is becoming mainstream in printing and plate making operations. For example, an image is read from an image document (a photograph, a positive film, or the like) by a scanner, and the obtained image data is stored in a storage device such as a magnetic disk. After that, a computer reads image data in a storage device and performs editing processing to generate plate making data.

[0003] Generally, in the plate making process, considerable fineness is required for an image to be handled. Therefore, it takes a long time to read the image document by the scanner.
The image data obtained by reading has a large data amount. Therefore, before performing the main scan, a so-called trimming operation is performed in which a pre-scan is performed with rough accuracy and a reading range of an image document is determined on the pre-scan image displayed on the display device. By performing such a trimming operation, during the main scan,
Without reading the entire readable area on the platen,
Only the necessary image portion can be read, the reading time of the image document can be shortened, and the amount of image data stored in the storage device can be reduced.

[0004]

However, the conventional trimming operation has been performed manually by an operator using a pointing device such as a mouse while watching a prescan image displayed on a display device. Therefore, there is a problem that the trimming operation requires time and effort.

Therefore, there has been proposed a method of extracting an outline of an image document from prescanned image data and automatically defining a trimming frame based on the outline. However, in such a conventional method, since the contour is obtained by comparing the density values of all the pixels constituting the prescan image data with the threshold value, it takes time for data processing.
Further, all coordinate positions (addresses) of the pixels located in the outline portion must be stored, and the memory capacity to be used increases. Furthermore, it is necessary to calculate the vertex coordinates of the image document from the obtained contour shape by approximation calculation, and the calculation process takes time.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image processing apparatus capable of performing a trimming operation automatically and quickly.

[0007]

Means for Solving the Problems and Effects of the Invention According to a first aspect of the present invention, a rectangular image original placed on an original platen is read with coarser accuracy than a main scan to obtain prescan image data, An image processing apparatus for setting a trimming area at the time of the main scan using the pre-scan image data, a plurality of sampling points arranged at an interval coarser than the interval of the pixels constituting the pre-scan image data, Setting means for setting the prescanned image data; extracting means for extracting a sampling point on the image document from among the plurality of set sampling points; and one of the extracted sampling points. Selecting means for selecting one of the sampling points, and tracing the outline of the image document with the selected sampling point as a start point, Vertex detection means for detecting the coordinates of each vertex of the image document; storage means for storing the coordinates of each detected vertex; and trimming for defining a trimming frame for the image document based on the vertex coordinates stored in the storage means. Frame defining means.

As described above, according to the first aspect, the coordinates of each vertex of the image document are detected by simply following the outline without extracting the contour of the image document. It is not necessary to check the density values of all the pixels constituting the prescan image data as in the related art, and data processing can be performed in a short time. Also, in the first invention, since only the coordinates of each detected vertex need be stored, the memory capacity used is smaller than in the conventional case where the coordinates of all pixels at the extracted contour position are stored. Need less. Further, since the coordinates of each vertex of the document coordinates are directly detected from the contour tracking result, it is not necessary to approximate each vertex of the image document from the extracted contour line as in the related art, and the calculation process is simplified. .

According to a second aspect based on the first aspect, the vertex detecting means traces one side of the image document in a predetermined direction and with a predetermined width, and If the next contour point does not exist within the width, it is determined that the contour point currently focused on is the vertex located at the end point of the side, and then the direction of the next side is changed by changing the direction by 90 degrees and tracking of the next side is started. It is characterized by doing.

A third invention is characterized in that, in the first invention, an interval between adjacent sampling points is selected to be smaller than a length of a side of a minimum size image document.

As described above, according to the third aspect, the interval between adjacent sampling points is selected to be smaller than the length of the side of the minimum-size image document. Regardless of the state of the image document, the image document includes at least one sampling point, so that the start point can always be selected reliably.

According to a fourth aspect of the present invention, there is provided a trimming area setting method for setting a trimming area at the time of a main scan using prescanned image data obtained by reading a rectangular image original with a higher accuracy than the main scan. Wherein the program data sets a plurality of sampling points arranged at intervals coarser than the intervals of the pixels constituting the prescan image data for the prescan image data. A first program step, a second program step of extracting sampling points on the image original from the set plurality of sampling points, and one sampling point from the extracted sampling points. The third program step to be selected and the selected sampling point as a starting point By tracking the outline of a document,
A fourth program step for detecting the coordinates of each vertex of the image document, a fifth program step for storing the detected coordinates of each vertex in the memory, and an image document based on the vertex coordinates stored in the memory. And a sixth program step for defining a trimming frame for.

According to a fifth aspect of the present invention, there is provided a trimming area setting method for setting a trimming area in a main scan using prescanned image data obtained by reading a rectangular image document with a higher accuracy than in a main scan. Providing program data for communication by communication,
The program data includes: a first program step of setting a plurality of sampling points arranged at an interval coarser than an interval of pixels constituting the prescan image data to the prescan image data; A second program step of extracting sampling points lying on the image original among the sampling points; a third program step of selecting one sampling point from the extracted sampling points; A fourth program step of detecting the coordinates of each vertex of the image document by tracing the contour of the image document using the sampling point as a starting point, and a fifth program step of storing the coordinates of each detected vertex in a memory. Based on the program steps and the vertex coordinates stored in the memory, the trimming frame for the image And a sixth program step of a constant.

[0014]

FIG. 1 is a block diagram showing the configuration of an image processing apparatus according to an embodiment of the present invention. In FIG. 1, an image processing apparatus according to the present embodiment includes a scanner 1,
Computer device 2, display device 3, and memory device 4
, A program memory 5 and an input operation device 9.

The scanner 1 is an image reading device that scans an image document placed on a document table and reads the image. The program memory 5 stores program data for the computer device 2. The computer device 2 operates according to the program data stored in the program memory 5 and controls the operation of other devices in FIG. The display device 3 displays a predetermined image according to an image signal provided from the computer device 2. The memory device 4 stores data of an image read by the scanner 1, various coordinate values, and the like. Input operation device 9
Includes a keyboard, a mouse, etc., and sends various data and instructions to the computer device 2 according to the operation of the operator.
To enter.

The program data to be executed by the computer 2 may be stored in the program memory 5 from the beginning of shipment of the image processing apparatus, or may be installed after delivery to the user. If installing later, use a floppy disk or CD-ROM.
Alternatively, the program data recorded on the recording medium 50 such as the above may be read and installed by a drive device, or the program data sent online may be installed.

FIGS. 2 to 4 are flowcharts for explaining the operation of the image processing apparatus shown in FIG. FIG.
FIG. 4 is a diagram illustrating a relationship between an image document placed on a document table and sampling points. FIG. 6 is a diagram showing a state in which the contour of the image document is tracked in order to obtain the coordinates of the four vertices of the image document. FIG. 7 is a diagram illustrating the tracking of the contour on one side of the image document in more detail. FIG. 8 is a diagram illustrating the tracking of the contour near the apex of the image document in more detail. FIG. 9 is a diagram illustrating a state in which it is determined that the current tracking position is the vertex of the image document.
FIG. 10 is a diagram illustrating a state where the tracking direction of the image document is changing. FIG. 11 is a diagram showing a state of sampling points in a state where the trimming operation for one image document has been completed. Hereinafter, the operation of the image processing apparatus shown in FIG. 1 will be described with reference to FIGS.

First, referring to FIGS. 1 and 5, an image document such as a photograph or a positive film is placed on a document table 11 of the scanner 1 (step S101), and the image document 12a
To 12e are prescanned by the scanner 1 (step S102). In FIG. 5, as an example, five image documents 12 a to 12 e are placed on the document table 11, but the number of placed image documents differs depending on the situation. As a result of the prescan, the prescanned image data is supplied from the scanner 1 to the computer device 2. Next, based on the supplied pre-scanned image data, the computer device 2 sets each of the image originals 12a to 12e
To set a trimming frame for (step S1)
03). Details of this subroutine step S103
This is shown in FIG.

Referring to FIG. 3, computer device 2 includes:
Multiple sampling points 6 on prescan image data
(In FIG. 5, reference numbers are assigned to only four sampling points to avoid complication in the drawing) and are set at regular intervals (step S201). These sampling points 6 are used to know the approximate position of the image document on the document table 11. The interval between the sampling points is set to be smaller than the length of the side of the minimum-size image document. Next, the computer apparatus 2 extracts sampling points (indicated by white circles in FIG. 5) on the image documents 12a to 12e from among the plurality of sampling points 6 set in step S201 (FIG. 5). Step S202). This extraction operation is performed by checking the pixel density at each sampling point 6. That is, the sampling point where the pixel density is equal to or less than the predetermined threshold is
It is determined that the sampling point is outside the image document (indicated by a black circle in FIG. 5). Next, the computer device 2 determines whether or not an image document exists on the document table 11, that is, whether or not at least one sampling point has been extracted in step S202 (step S203).

When an image document exists on the document table 11,
That is, when the sampling points extracted in step S202 exist, the computer device 2 detects the start point at which the tracking of the outline of the image document is started (step S202).
204). In the present embodiment, as an example, among the sampling points extracted in step S202, the sampling point located at the uppermost position and the leftmost position is set as the start point (P1 in FIG. 5). Next, the computer device 2 detects four vertices of the image document (in FIG. 5, the image document 12a) including the start point P1 (step S205). This subroutine step S205
Are shown in FIG.

Referring to FIG. 4, computer device 2 includes:
First, the left end of the image document 12a is detected (Step S).
301). In this detection, as indicated by an arrow A in FIG. 6, starting from the start point P1, the pixel density of the prescanned image data on the same main scanning line is determined in the direction opposite to the main scanning direction (hereinafter, the reverse main scanning direction) This is done by examining along the line. That is, the pixel position where the pixel density changes rapidly (more specifically, the position of a pixel whose density difference from the next pixel is larger than a predetermined threshold) is
It is determined that it is the left end of the image document 12a. In the example shown in FIG. 7, the pixel position 7
1 is detected. Next, the computer device 2 determines a direction in which the contour of the image document 12a is tracked (Step S).
302). In the example of FIG. 6, the tracking direction is a direction opposite to the sub-scanning direction (hereinafter, referred to as a reverse sub-scanning direction). Next, as shown in FIG. 7, the computer device 2 detects a next edge position of the image document 12a at a predetermined interval Δt from the pixel position 71 (step S303). More specifically, the computer device 2 is configured such that, on a main scanning line separated from the pixel position 71 by Δt in the reverse sub-scanning direction,
The edge position of the image document is detected within a range of a predetermined width w around the sub-scanning position corresponding to the pixel position 71.
Thereby, in the example of FIG. 7, the next end position 72 is detected.

Next, the computer 2 determines whether or not the end position of the image document 12a has been detected in step S303 (step S304). Normally, the determination in step S304 is YES except when the left side of the image document 12a is extremely inclined with respect to the sub-scanning direction or when the pixel position near the vertex of the image document 12a is detected. Therefore, the computer device 2 returns to the operation of step S303, and detects the next end position of the image document 12a. Step S303 and step S3
By repeating the operation of Step 04, the end positions of the left side of the image document 12a are successively detected (the end positions 73,
74, ...). That is, at this time, the computer device 2 is tracking the outline of the left side of the image document 12a.

Here, as shown in FIG. 8, the operation when the end position of the image document 12a detected so far is the end position 75 near the vertex will be described. In this case, since the left side of the image original 12a ends at the vertex immediately before the end position 75, the image original 1 is placed on the main scanning line spaced apart from the end position 75 in the reverse sub scanning direction by Δt.
There is no end position of 2a (see FIG. 8). Therefore, the determination result of step S304 is NO. In this case, the computer device 2 returns to the immediately preceding end position 75, and sets the line interval for detecting the next end position to half of that (ie, Δt / 2) (step S30).
5). Next, the computer device 2 executes step S305.
It is determined whether or not the line interval set in step 1 is equal to or less than one pixel (step S306). At this time, the line interval is 1
Since it is larger than the pixel, the computer device 2 returns to the operation of step S303, and the image original 1 is placed on the main scanning line spaced from the end position 75 in the reverse sub-scanning direction by Δt / 2.
The end position of 2a is detected (see FIG. 8). If the end position of the image document 12a is not detected at this time, the computer device 2 sets the line interval to half (ie, Δt / 4) and detects the next end position ( See FIG. 8). In FIG. 8, the line interval is Δ
At t / 4, the next end position 76 has been detected.

The image original 1 to be detected as described above
The end position of 2a gradually approaches the vertex. As shown in FIG. 9, when the next end position is not detected even if the line interval is reduced to one pixel, the current end position is set to the vertex position α1.
Is recorded in the memory device 4 (step S307). Next, the computer device 2 determines whether four vertices have been detected for the image document 12a (step S308). At this time, since only one vertex α1 has been detected, the determination is NO, and the computer apparatus 2 rotates the contour tracking direction of the image document 12a by 90 degrees (step S309). Thereby, the image original 1
The contour tracking direction 2a matches the main scanning direction as shown in FIG. Thereafter, the computer device 2 returns to the operation of step S303, traces the upper side of the image document 12a, and finally detects and records the vertex α2. By repeating the above operation, when all vertex positions of the image document 12a are detected, the determination in step S308 becomes YES, and the process returns to the routine of FIG.

Referring again to FIG.
Calculates a circumscribed rectangle 8 (see FIG. 6) passing through the four vertices α1 to α4 and having no inclination with respect to the main scanning direction and the sub-scanning direction (step S206). Next, the computer device 2 determines whether or not the size of the circumscribed rectangle 8 obtained in step S207 exceeds the minimum size of the image document (step S207). If the size of the circumscribed rectangle 8 is smaller than the minimum size of the image document, the start point is not the original sampling point but is likely to be noise (for example, dust or scratches on the document table 11). The start point is deleted without using the obtained circumscribed rectangle as the trimming frame (step S208). On the other hand, when the size of the circumscribed rectangle 8 exceeds the minimum size of the image document,
The computer device 2 converts the circumscribed rectangle 8 into an image document 12
It is adopted as a trimming frame for a and registered in the memory device 4 (step S209). Next, the computer device 2 deletes the sampling points existing in the area 12a (see FIG. 6) formed by the four vertices α1 to α4 from the detection target (step S210). As a result, sampling points remaining as detection targets of the next start point are sampling points indicated by white circles in FIG.

Next, the computer 2 determines whether or not there is still an image document for which a trimming frame is to be defined, ie, whether or not the sampling points extracted in step S202 still remain (step S203). . If there is still an image document for which the trimming frame should be specified,
The computer device 2 repeats the operation from step S204 onward, and defines and registers a trimming frame for the image document 12b with the start point set to P2. The above operation is repeatedly performed, and all the image originals 12 a to 12
When the definition and registration of the trimming frame for e are completed, the determination in step S203 is NO, and the process returns to the routine of FIG.

Referring again to FIG.
Displays the pre-scanned image and the trimming frame specified for each image document on the display device 3 (step S104). Thereby, the operator can confirm whether or not the trimming frame is accurately defined for each image document. Even if the trimming frame is accurately defined, the trimming frame can be changed according to the circumstances. Next, the computer device 2 causes the scanner 1 to perform a main scan (read at a high resolution) of the image document (step S105).
At this time, the scanner 1 receives the vertex coordinate values of the trimming frame from the computer device 2 and executes the main scan on the document table 11 with only the reading range within the range connecting the respective vertex coordinates. Thus, the main scan can be performed in a short time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the image processing apparatus illustrated in FIG. 1;

FIG. 3 is a sub-flowchart showing in detail a process in a subroutine step S103 shown in FIG. 2;

FIG. 4 is a sub-flowchart showing in detail a process in a subroutine step S205 shown in FIG. 3;

FIG. 5 is a diagram showing a relationship between an image document placed on a document table and sampling points.

FIG. 6 is a diagram illustrating a state in which the contour of an image document is tracked in order to obtain the coordinates of four vertices of the image document.

FIG. 7 shows how a contour on one side of an image document is tracked;
FIG.

FIG. 8 is a diagram illustrating in more detail how the contour is tracked near the apex of the image document.

FIG. 9 is a diagram illustrating a state in which it is determined that a current tracking position is a vertex of an image document.

FIG. 10 is a diagram showing a state where the tracking direction of an image document is changing.

FIG. 11 is a diagram illustrating a state of sampling points in a state where a trimming operation on one image document has been completed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Scanner 2 ... Computer device 3 ... Display device 4 ... Memory device 5 ... Program memory 50 ... Recording medium 6 ... Sampling point 9 ... Input operation device 11 ... Origin table 12a-12e ... Image document α1-α4 ... Vertex

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naohiko Kawashima 5 Higashikujo Minamiishidacho, Minami-ku, Kyoto Dainippon Screen Mfg. Co., Ltd.

Claims (5)

[Claims] 1. A pre-scan image data is obtained by reading a rectangular image document placed on a platen with a coarser accuracy than a main scan, and a trimming area at the time of a main scan using the pre-scan image data. An image processing apparatus for setting a plurality of sampling points arranged at intervals coarser than the intervals of pixels constituting the prescan image data, setting means for setting the prescan image data Extracting means for extracting a sampling point on the image document from the plurality of set sampling points; selecting means for selecting one sampling point from the extracted sampling points; By tracking the outline of the image document using the selected sampling point as a start point, each vertex of the image document is traced. Vertex detection means for detecting a mark; storage means for storing the coordinates of each detected vertex; and trimming frame defining means for defining a trimming frame for the image document based on the vertex coordinates stored in the storage means. An image processing device comprising: 2. The apex detecting means traces one side of the image document in a predetermined direction and with a predetermined width, and a next contour point is located within the predetermined width. If not present, the contour point of interest is determined to be the vertex located at the end point of the side, and then the tracking of the next side is started by changing the direction by 90 degrees. Item 2. The image processing device according to Item 1. 3. The interval between adjacent sampling points is:
The image processing apparatus according to claim 1, wherein an interval is selected to be smaller than a length of a side of the minimum size image document. 4. A program data for executing a trimming area setting method for setting a trimming area at the time of main scanning using prescanned image data obtained by reading a rectangular image original with coarser accuracy than the main scanning. The storage medium, wherein the program data sets a plurality of sampling points arranged at an interval coarser than an interval of pixels constituting the prescan image data to the prescan image data. And a second program step of extracting a sampling point on the image original from the plurality of set sampling points; and one sampling point from the extracted sampling points. A third program step of selecting the selected sampling points; As a point, by tracking the contour of the image original, the fifth to store a fourth program step of detecting the coordinates of the vertices of the image original, the detected respective vertex coordinates are in the memory
And a sixth program step of defining a trimming frame for the image document based on the vertex coordinates stored in the memory. 5. Program data for executing a trimming area setting method for setting a trimming area at the time of main scanning using prescanned image data obtained by reading a rectangular image document with a higher accuracy than that of the main scanning. A method of providing the program data by communication, wherein the program data sets a plurality of sampling points arranged at an interval coarser than an interval of pixels constituting the prescan image data to the prescan image data. One program step; a second program step of extracting sampling points on the image original from the plurality of set sampling points; and one sampling step from the extracted sampling points. A third program step of selecting a point; the selected sampling point As a starting point, by tracking the contour of the image original, first stores a fourth program step of detecting the coordinates of the vertices of the image original, the detected respective vertex coordinates are in the memory 5
And a sixth program step of defining a trimming frame for the image document based on the vertex coordinates stored in the memory.