JP3065364B2 - Cutout mask making method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming a cutout mask, and more particularly to a method and an apparatus for forming a cutout mask by displaying image data on a screen.

[0002]

2. Description of the Related Art In removing unnecessary portions of an image and extracting only a necessary object shape, a cutout mask is created using an electronic computer image processing system, and cutout is performed using the cutout mask by an image processing technique. Done.

[0003] When a cutout is made by using a cutout mask, the cutout mask is prepared by various methods.

[0004] That is, in the clipping mask creation method, image data is displayed on a screen, and an operator refers to the display screen and traces a contour line of an object shape to be clipped on the screen, and the clipping mask is formed. There is a way to create In this method, first, an operator inputs a point sequence along a contour to be cut out, connects the input point sequence with a straight line, and creates a cutout mask using the connected straight line as a cutout line. .

There is also a method of generating a smooth cutout line using an arc or a spline curve for an object shape having a curved contour line. This spline curve is created by interpolating a given plurality of point sequences with a curve (according to a certain rule). Also, the spline curve has a second order, a third order, and a degree, and a given point sequence whose degree is not determined in advance is uniquely determined (a curve to be drawn). Curves represented by different mathematical formulas are connected to each other for each section up to, and the resulting curve is smooth at all points (that is, at intermediate points and at seams).

Here, an important point in the cutting operation is as follows.
This is to trace the contour of the object shape to be cut out faithfully and smoothly.

[0007]

However, the conventional clipping method has a problem that, depending on the object shape to be clipped, it is difficult to trace the contour of the object shape faithfully and smoothly. is there.

That is, in the method of forming a cutout line by a straight line connecting the input point sequence, a smooth cutout line corresponding to a curve or the like cannot be formed unless a point sequence is input very finely. The shape of the object to be clipped is limited.

In the method using an arc, it is often difficult to draw a curve appropriately corresponding to a contour line that changes naturally.

In the method using the spline curve, the obtained curve is smooth as described above, but the shape of the entire curve is indefinite until the last point of the point sequence is input. A curve partially deviating from the curve intended by the operator may occur, and it is difficult to obtain a desired cutout line.

This difficulty is not solved even if the number of input points is increased, and even if the operator inputs a point sequence on the contour line quite finely, the interpolated curve deviates from the desired contour line. Sometimes.

The present invention has been made in order to solve the above-mentioned conventional problems, and a desired cutout line is easily fitted (matched) to a contour line of an original image by a simple operation.
An object of the present invention is to provide a method and an apparatus for producing a cutout mask that can be produced with high quality.

[0013]

According to the present invention, there is provided a method of displaying an image data on a screen and forming a cutout mask, the method comprising the steps of: Inputting a start point and an end point, and inputting an arbitrary control point of the Bezier curve, generating a Bezier curve based on the input start point, end point and control point, and displaying the generated Bezier curve together with the image. A step of displaying the above, and a step of re-inputting at least one of a start point, an end point, and a control point when a Bezier curve corresponding to the contour line cannot be obtained with reference to the Bezier curve and the image on the display screen And a step of forming a cutout line from a Bezier curve corresponding to the contour line.

Further, in an apparatus for displaying image data on a screen of an image display means to create a cutout mask, a start point and an end point of a Bezier curve are defined in correspondence with a contour of an object shape to be cut out of a display image. Means for inputting and inputting any control point of the Bezier curve, means for generating a Bezier curve based on the input start point, end point and control point, and displaying the generated Bezier curve together with the image. Referring to the Bezier curve and the image on the display screen, when the Bezier curve corresponding to the contour line cannot be obtained, re-input at least one of the start point, the end point, and the control point Means for creating a cutout line from a Bezier curve corresponding to the contour line, and means for creating cutout mask data based on the created cutout line. By was example it is intended to solve the above problems.

[0015]

When the inventor creates the cutout mask,
Various studies were performed to create a smooth cutout line along the contour of the object shape to be cutout.

As a result, the idea of using various Bezier curves along the contour line of the object shape has been conceived.

That is, first, a Bezier curve is generated by inputting a start point, an end point, and a control point. The generated Bezier curve is displayed on the screen together with the image to be clipped. With reference to the display image, the start point, the end point, and the control point are re-input as necessary, and it has been found that the optimum one of the Bezier curves is selected as the cutout line. In this Bezier curve, various curves can be obtained by changing the coordinates of the start point, end point, and control point as the generation conditions.

The present invention has been made based on the above-mentioned knowledge, and is intended to create a desired cutout line with a high quality so as to fit (match) a contour line of an original image with a simple operation. Can be. Therefore, the quality of the cutout mask can be improved.

Here, the Bezier curve will be described.

This Bezier curve is represented by P.A. It was studied by Bezier (P. Bezier, France).

A general nth-order Bezier curve is created from the (n + 1) feature points by the equation shown in (1).

[0022]

(Equation 1)

Here, Bn (x, y): coordinates of the generated curve t: parameter (0 ≦ t ≦ 1) Pi (x, y): coordinates of the feature point, P0 is the start point, and Pn is the end point is there.

By changing the parameter t from 0 to 1 according to the equation (1), an nth-order Bezier curve having both ends of the start point P0 and the end point Pn is created.

In expressing computer graphics and character fonts, a cubic Bezier curve is often used. In practicing the present invention, any order Bezier curve can be used. However, since it is necessary to input a large number of control points in a higher-order Bezier curve, in a later-described embodiment, the minimum number of control points (1
) Is used. The quadratic Bezier curve will be briefly described below.

In the quadratic Bezier curve, the feature points are three points of a start point (x0, y0), a control point (x1, y1), and an end point (x2, y2).
Consists of dots. Assuming that the coordinates of the point on the generated Bezier curve are (x (t), y (t)), from the general formula (1), the coordinates (x (t), y (t)) are expressed by the following formula ( 2),
It is obtained as in (3).

[0027] x (t) = (1- t) 2 · x0 + 2 (1-t) · t · x1 + t 2 · x2 ... (2)

[0028] y (t) = (1- t) 2 · y0 + 2 (1-t) · t · y1 + t 2 · y2 ... (3)

As shown in FIG. 2, the obtained Bezier curve passes through the start point P0 and the end point P2, and also has the middle point M2 of the straight line connecting the points P0 and P2 and the middle point M2 connecting the control point P1.
It becomes a curve passing through. Note that this curve is an elliptical arc.

Here, when obtaining a preferable cutout line using a quadratic Bezier curve, the control point P1 can be found, for example, in the following procedure.

That is, the operator first specifies two start points P0 and two end points P2 on the contour line. At this time, an outline between the start point P0 and the end point P2 is taken within a range in which the curve is oriented in a certain direction so as not to form an S-shaped curve. This operation is performed at the starting point P0
It is easy to set the end point P2 so as not to be too far from the terminal.

Next, the control point P1 is determined. In the quadratic Bezier curve, even if the start point P0 and the end point P2 at both ends are determined,
Since there are still two-dimensional degrees of freedom, it is possible to fit curves with various bending conditions.

In this case, the target curve is the starting point P0 at both ends.
, May be asymmetric with respect to the end point P1 (vertical bisector).

If a curve is drawn in real time as the control point P1 moves, the operator moves the control point P1 so that the drawn curve gradually approaches the target curve, thereby making it possible to move the curve from the plane. , The optimum control point P1 can be found without difficulty.

Therefore, a cutout line can be created by an easy operation.

[0036]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In this embodiment, as shown in FIG. 1, a Bezier curve is generated by input of a feature point by an operator, a cutout line is determined from the Bezier curve, and a cutout mask is created.

As shown in FIG. 1, the cut-out mask forming apparatus includes an output unit 14 formed of, for example, a color cathode ray tube (color CRT) for displaying an image, for example, a color image, on a video screen; An input unit 10 for inputting a position to be performed as a feature point, a storage 12 for saving image data to be displayed on the screen, cutout mask data, and the like; image data read from the storage 12; A frame memory 16 for temporarily storing the mask data created by the cutout processing units 18 and 20 and displaying the mask data on the screen of the output unit 14, and an image cutout mask are automatically generated based on the image data on the frame memory 16. An automatic cutout processing unit 18 for creating a cutout line according to the present invention based on the input feature points, or cutout by various methods. Specified, the manual cut-out processing unit 20 for creating a cut-out mask data from the cutout line
And a control central processing unit (CPU) 22 for controlling the cutout processing units 18 and 20 and the like.

The input unit 10 may be, for example, a mouse or a digitizer. In the embodiment, the cursor on the screen is moved in accordance with the movement of the mouse, and the position coordinates of the cursor are input by turning on and off switches provided on the left and right of the mouse.

The image data input to the frame memory 16 may be input from an image data input unit 24 such as a scanner. The input image data is directly input to the frame memory 16 or, once,
It can be stored in the storage 12, read as needed, and input to the frame memory 16.

As the image data, image data created by another image creating apparatus and recorded on a magnetic disk, an optical disk, or the like can be used.

The automatic cutout processing section 18 creates cutout mask data based on image data by various methods (for example, Japanese Patent Application No. 2-38104, which has already been submitted by the applicant).

After the cutout line is created, the manual cutout processing section 20 designates which side of the cutout line as the boundary or the background area by the operator's selection or by automatic selection, and The mask data is turned on in the area defined as the area, and cutout mask data is created.

Next, the operation of the embodiment will be described.

In the cutout mask producing apparatus according to the embodiment, the cutout processing is performed according to the procedure shown in FIG.

That is, as shown in FIG. 3, first, the color image data is transferred from the storage 12 to the frame memory 16, and the image is displayed on the screen of the output unit 14 at various magnifications (step 101). The operator refers to the display image and manually cuts out (step 102) or
One of the automatic cutout processes (step 103) is selected, and cutout mask data is created according to the selected cutout process. In this case, the operator specifies, as necessary, which side of the area bounded by the cutout line is the background area. Alternatively, the background area is automatically specified. For this designated background area, the mask data is turned on, and cutout mask data is created.

Next, the created mask data is stored in the storage 12 (step 104).

The mask data can be transferred to an image editing device (not shown) or a mask output device, in addition to being saved as described above.

Here, in general, the clipping process is performed by using a method of tracing a clipping line by inputting coordinate data of a feature point from an input unit while referring to a screen, and a processing technique of image processing. A method of automatically creating a cutout line can be roughly divided into two methods. However, depending on the state of the image to be clipped, a desired clipping line may not be obtained by the automatic clipping method. In such a case, it is necessary to create a cutout line using a manual cutout processing technique.

Therefore, in the embodiment, the process proceeds to a manual cutout processing step (step 102) by the selection of the operator.
A cutout line by a manual cutout process is created according to the present invention. In addition, a cutout line is created by tracing a contour line as necessary.

Hereinafter, the detailed procedure of the manual cutting process according to the present embodiment will be described with reference to the flowchart of FIG.

That is, first, the operator refers to the object shape to be cut out displayed on the screen and moves the position of the simultaneously displayed cursor to set one point on the contour line of the object shape as the starting point P0. An instruction is given using the cursor (step 201). In this case, the operator inputs the coordinates (x0, y0) of the point P0 indicated by the cursor on the screen by pressing and clicking the left button on the mouse of the input unit 10. FIG. 5A shows an example of the starting point P0 indicated by the cursor. In addition, (A)-(D) of FIG.
Here, the cursor is indicated by an arrow.

Next, the manual cutout processing section 20 draws a straight line between the input start point P0 and the coordinates indicated by the cursor,
The straight line is displayed on the screen in real time as shown in FIG. 5A (step 202). The display of this straight line is calculated and displayed each time the cursor moves. or,
By operating the mouse, the operator moves the cursor to a point on the contour line extending from the start point P0 as shown in FIG. 5B.

Next, when displaying the straight line between the start point P0 and the cursor, if the input coordinates of the start point P0 are to be corrected, or if the clipping process is to be performed by another method, the coordinates of the end point P2 are determined. The input of (x2, y2) can be canceled (step 203).

As described above, when the coordinate input is stopped, the process proceeds to step 210 to check whether the Bezier curve to be input is the first one.

In the first case, the Bezier curve input processing ends. On the other hand, if it is not the first curve, the coordinates (x0, y0) of the start point P0 are returned to the start point of the curve created immediately before, and the previous Bezier curve itself is canceled (step 21).
1) Return to step 202.

On the other hand, when inputting the coordinates of the end point P2, the coordinates of the point designated by the cursor are changed to the end point P of the Bezier curve.
2 (x2, y2) (step 20)
4).

Next, a point designated by the cursor is temporarily input as coordinates (x1, y1) of the control point P1. From the coordinates (x0, y0), (x2, y2), (x1, y1) of the input start point P0, end point P2, and control point P1, the Bezier curve is obtained using the above equations (2) and (3). (X (t), y
(T)) is created, and the Bezier curve is displayed on the screen in real time (step 205). An example of the Bezier curve displayed in this way is shown in FIG.

The operator moves the control point P1 by using the cursor.
Are variously changed to display various Bezier curves on the screen. At this time, while referring to the displayed Bezier curve, a control point P1 where the Bezier curve coincides with the contour line is searched.

It is determined whether a satisfactory Bezier curve has been obtained, and if so, the coordinates designated by the cursor are determined as the coordinates (x1, y1) of the control point P1 (step 206). Thereby, one cutout line is determined.

On the other hand, if a satisfactory curve cannot be obtained, the flow returns to step 202 to set the end point P2 again (step 206). Note that the quadratic Bezier curve is a quadratic curve, and can represent only a curve having one bend, and it is necessary to set the curve to match the contour.

Next, the coordinates (x
1, y1) is set, and the current Bezier curve is set and stored (step 207).

Next, it is determined whether or not to continue the cutout line creation processing (step 208).
Coordinate P2 of the end point of the Bezier curve set in step 207
The coordinates (x0, y2) of the starting point P0 of the new Bezier curve (x0, y2)
y0) (step 209), the process returns to step 202 to create a new Bezier curve. The state of the cursor in this case is as shown in FIG. 5D, and the procedure after step 202 is repeated again to create the next curve.

On the other hand, when one cutout line is created and the cutout line creation processing is not continued, an end signal is input by a mouse to determine the entire cutout line created.
Cutout mask data is created from the cutout line data and input to the storage 12 or the like.

The determined cutout mask data is output to the layout scanner, and the layout scanner reads out the color image data to be extracted from the color image data stored in the image memory while referring to the cutout mask data. Cut out the print film plate for each color and output it.

The determined cutout mask data is output to an automatic drawing machine having a mask cutter, and the automatic drawing machine may create a cutout mask film in accordance with the data.

In the above-described embodiment, the quadratic Bezier curve is created by the above equations (2) and (3). However, the Bezier curve when the present invention is implemented is such a quadratic Bezier curve. The Bezier curve of another order can be used without being limited to this.

Here, the quadratic Bezier curve is eventually a quadratic curve, and only a curve having one curve, that is, a curve having at least one maximum (or minimum) point can be created. . Therefore, if the contour has a complicated shape and corresponds to a tertiary or higher-order curve, a second-order Bezier curve cannot be matched with the contour. In such a case, a cubic or higher order Bezier curve can be used. However, when a cubic or higher-order Bezier curve is used, the range in which the curve can be expressed is widened, but it is necessary to input a plurality of control points to perform the calculation, so that the operation and the calculation are troublesome. On the other hand, since the calculation of the second-order Bezier curve is simpler than that of the third-order or higher, the calculation speed is fast, real-time display can be performed quickly and reliably, and the control point can be determined quickly.

Further, in the above-described embodiment, the cutout mask forming apparatus having the structure as shown in FIG. 1 has been exemplified. However, the apparatus for implementing the present invention is not limited to the one shown in the figure, and the present invention may be applied to other structures. Can be implemented. For example, the present invention can be implemented by a cutout mask creating apparatus in which cutout lines are created by manual setting without automatically arranging the automatic cutout processing units 18.

[0070]

As described above, according to the present invention, a desired cutout line can be created with a high quality so as to fit (match) the outline of the original image with a simple operation. Therefore, an excellent effect that the quality of the mask data can be improved can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a cutout mask producing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a state in which a quadratic Bezier curve is created for explaining the principle of the present invention.

FIG. 3 is a diagram for explaining the operation of the embodiment.
9 is a flowchart showing a mask creation procedure.

FIG. 4 is a flowchart showing in detail a cutout line creation procedure in the mask creation procedure.

FIG. 5 is a plan view showing a display example of a Bezier curve and a processed image when a cutout line is created.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... input part, 12 ... storage, 14 ... output part, 16 ... frame memory, 20 ... manual cutout processing part, 22 ... control central processing unit (CPU), 24 ... image data input part.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuhiko Tanaka 1-1-1 Ichigaya-Kagacho, Shinjuku-ku, Tokyo Dai Nippon Printing Co., Ltd. (56) References JP-A-58-176638 (JP, A) JP-A-59-226347 (JP, A) JP-A-64-81955 (JP, A) JP-A-3-46657 (JP, A) JP-A-3-240884 (JP, A) (58) Int.Cl. ⁷ , DB name) G03F 1/00-1/16

Claims (2)

(57) [Claims] 1. A method for creating a clipping mask by displaying image data on a screen, wherein a starting point and an ending point of a Bezier curve are input in correspondence with a contour line of an object shape to be clipped of a display image. Inputting an arbitrary control point of the Bezier curve, generating a Bezier curve based on the input start point, end point and control point, displaying the generated Bezier curve together with the image on a screen, and displaying Referring to the Bezier curve and the image on the screen, when a Bezier curve corresponding to the contour cannot be obtained, re-inputting at least one of a start point, an end point, and a control point; Creating a cutout line from a Bezier curve. 2. An apparatus for displaying an image data on a screen of an image display means to create a cutout mask, wherein a start point and an end point of a Bezier curve are defined in correspondence with an outline of an object shape to be cut out of a display image. Means for inputting and inputting an arbitrary control point of the Bezier curve; means for generating a Bezier curve based on the input start point, end point and control point; and displaying the generated Bezier curve together with the image. Referring to the Bezier curve and the image on the display screen, when the Bezier curve corresponding to the contour line cannot be obtained, re-input at least one of the start point, the end point, and the control point Means for creating a cutout line from a Bezier curve corresponding to the contour line, and means for creating cutout mask data based on the created cutout line. A cutout mask making apparatus, characterized in that: