KR20040043532A - Method and record device recoded program for correcting distortion to generate in case of writing on tablet monitor using electronic pen - Google Patents

Abstract

PURPOSE: A hand shake compensation method and a computer readable media for implementing the same method are provided to detect a hand shake from a vector size and a vector orientation variation, to stabilize a position of a coordinate, and to approximate a curve according to the stabilized position of the coordinate. CONSTITUTION: The method comprises several steps. A reference point, P0, is specified, and three other points, P1, P2, P3 are specified according to regular periods(S41). Three vector values of P1, P2,and P3 from P0 are calculated(S42). It is checked whether the interval between P1 and P2 is over a threshold(S43). If the interval is over a threshold, a curve, connected among the three points, is naturally formed(S46). If the interval between P1 and P2 is under a threshold, it is checked whether a vector value of P2 is positioned within an allowance(S44). If the vector value of P2 is positioned within an allowance, a curve, connected among the three points, is naturally formed(S46).

Description

Method of correcting hand shake when writing on a copyboard using an electronic pen and a computer-readable recording medium recording a program that performs the method of writing on tablet monitor using electronic pen}

The present invention relates to a technique for compensating for hand shake that occurs when writing on an electronic blackboard using an electronic pen, and more particularly, when writing using an electronic pen on an electronic blackboard unlike a general writing environment. The present invention relates to a method for compensating for hand shake, which is a slight deviation of a pen, which is unintentionally generated depending on the type of a paper and the state of a writing surface, and a computer-readable recording medium recording a program for executing the method.

In general, such as tablet LCD monitors (hereinafter referred to as "electronic blackboards"), which are used as lectures or mobile presentation tools in classrooms, auditoriums, conference rooms, etc., writing instruments used for writing or drawing on real paper or drawing paper In order to reflect the characteristics as it is, according to the degree of force applied by the user, a thin tip like a ballpoint pen is used to change the amount of force pushed into the pen to a numerical value and use the electronic pen to transmit to the electronic board. In the case of writing by hand, in addition to the actual handwritten content, unintended hand shake is included.

Here, the hand shaking refers to a fine departure of an unintended pen caused by a difference in the state of the type of pen and the writing surface, even when writing with the same writing feeling in an environment different from a general writing environment.

In other words, writing is necessary for lectures and presentations while using the electronic pen on the electronic blackboard. Due to the state of the writing surface on the electronic blackboard and the material characteristics of the electronic pen, a pencil or a ballpoint pen on a real paper or drawing paper Unlike writing or drawing with a writing instrument, the handwriting is slippery, which causes frequent hand shake and pen movement.

The hand shake is not enough to damage the written content as a whole, but it appears in various places of the written content, making it difficult to save the content of the continuous natural writing as a whole and reducing the readability of the written content.

In addition, when writing or drawing on an electronic blackboard using an electronic pen, most of them are expressed in the form of a curve or a straight line close to the curve. However, the computer recognizes the handwriting content by positioning only the X and Y coordinate values on the screen at each time point, and expresses the handwriting content by connecting the points in a proper manner.

In this case, not only does the discrete nature of the computer move the pen's position continuously to the coordinates on the computer, but it also predicts the movement of the pen by connecting the coordinates in a straight line. This results in a somewhat distant result from the natural pen movement.

Therefore, eliminating or minimizing hand shake that occurs when writing on an electronic blackboard using an electronic pen can substantially eliminate the display of unnatural handwriting caused by the discrete characteristics of the computer mentioned above. As a method of compensating for hand shake so that the handwritten content is displayed naturally and cleanly, it is possible to remove or minimize hand shake by maintaining a large movement distance of the pen such that hand shake caused by fine movement is neglected. Doing.

1A and 1B illustrate a process before and after correcting hand shake caused when writing on an electronic blackboard using an electronic pen by increasing a moving interval when obtaining position information of a conventional electronic pen. For example, if the electronic pen is kept at a distance over a certain distance, the pen movement itself becomes dull and fine tremors are buried by large movements so that the hand tremors do not appear.

That is, when the pen moves below a certain distance, it is not regarded as the movement of the pen. It is defined as the pen movement only when the pen moves more than a certain distance, and the distance between the pen's previous position and the current position is calculated and moved. When the current position of the pen is ignored, the position of the next pen is fetched, and when it moves over a certain distance, the current position of the pen is recognized and a line is drawn from the previous position to the current position.

Specifically, as can be seen in the drawing of FIG. 1A, when calculating the distance from the point P2 to the point P3, if the positions of the two points P2 and P3 are close to each other or less than a certain distance, the value of the point P3 is ignored and again. When calculating the distance from the point P2 to the point P4, if the positions of the two points P2 and P4 move away from each other by a certain distance, the point P4 is regarded as one point.

Again, when calculating the distance from point P4 to point P5, if the positions of the two points P4 and P5 are close to each other or below a certain distance, the value of point P5 is ignored, and when calculating the distance from point P4 to point P6 again, If the positions of the points P2 and P6 move away from each other by a certain distance, the point P6 is regarded as one point.

As a result of the above, as shown in Fig. 1B, a small straight line absorbs the minute hand shake so that a state in which the hand shake is eliminated or minimized can be displayed.

However, in this conventional method, since the movement distance of the electronic pen is removed by ignoring the points constituting the short distance, the hand shake caused by the electronic pen can be eliminated or minimized. In particular, when drawing with the electronic pen a curve that has a sharp change of direction, the display is worse than the original intended result.

Specifically, as can be seen from FIG. 2A and FIG. 2B showing the case where the before and after process of correcting the hand shake of FIG. 1A and FIG. 1B is applied to the rapidly changing curve, the shape of the originally intended curve is distorted. There is a problem represented by a set of small straight lines.

From this, the present invention is to solve the above problems, it occurs when writing on the electronic blackboard using an electronic pen that improves the readability of the handwriting content while maintaining the content of naturally continuous handwriting by eliminating or minimizing hand shaking An object of the present invention is to provide a method of compensating for hand shake and a computer-readable recording medium having recorded thereon a program for executing the method.

1A and 1B illustrate a process before and after correcting hand shake caused when writing on an electronic blackboard using an electronic pen by increasing a moving interval when obtaining position information of a conventional electronic pen. ,

2A and 2B show a case where the before and after process of correcting the hand shake of FIGS. 1A and 1B is applied to a rapidly changing curve,

3 is a block diagram showing an entire system for correcting hand shake caused when writing on an electronic blackboard using an electronic pen according to an embodiment of the present invention;

4 is a flowchart illustrating a process of correcting hand shake caused when writing on an electronic blackboard using an electronic pen in the overall system of FIG. 3;

FIG. 5 illustrates an example in which a location point of an electronic pen for determining hand shake that occurs when writing on an electronic blackboard using an electronic pen according to an embodiment of the present invention is specified.

FIG. 6 illustrates determination of whether the writing direction is out of the position points of the specified electronic pen of FIG. 5;

FIG. 7 illustrates a movement of an intermediate point when the direction of writing is out of the determination process of FIG. 6;

8 shows an example of applying a B-spline curve algorithm employed for curve processing in one embodiment of this invention,

FIG. 9 illustrates a curve process to naturally connect between the position points that have undergone the movement process of FIG.

10A to 10C illustrate each step of stabilizing hand shake according to an embodiment of the present invention.

11A and 11B show a result of correcting hand shake by employing a B-spline curve algorithm according to another embodiment of the present invention to curve processing.

<Description of the symbols for the main parts of the drawings>

10: whole system

11: electronic blackboard

111: electronic pen

12: handwriting content processing device

121: handwriting content processing unit

122: memory section

13: display device

In order to achieve the above object, the present invention is a position point of the electronic pen recognized on the electronic blackboard, so that a plurality of position points specified at regular intervals after the reference time point are naturally connected to the reference position point specified at the reference time point. Provided is a method for correcting hand shake that occurs when writing on an electronic blackboard using an electronic pen characterized in that it is processed into a curve.

Preferably, a Bezier-spline curve algorithm may be applied to curve processing that allows the location points to be naturally connected.

Preferably, three positions specified at regular intervals after the reference time point based on the reference position point specified at the reference time point as a position point of the electronic pen recognized on the electronic blackboard before the curve processing for allowing the position points to be naturally connected. From the vector values obtained for each of the points, the second of the three positions is traveling in a different direction than the first and the third positions, and the second and first positions If it is determined that the interval is less than or equal to the threshold, the second location point may be moved so that the three location points face one travel direction.

More preferably, the threshold value determination of the interval between the second position point and the first position point among the three position points may be twice the minimum moving distance of the electronic pen.

More preferably, the second location point for directing the three location points in one travel direction is first based on the reference location point while maintaining the length from the reference location point to the second location point. It may be moved to the intermediate value of the angle formed by the vector values obtained for the first and third position points.

In addition, in order to achieve the above object, the present invention provides a computer as a reference point as a position point of the electronic pen recognized on the electronic blackboard to correct hand shake occurring when writing on the electronic blackboard using the electronic pen. Based on the reference position point specified in, the second position point of the three position points is the first position point and the third position point. If the distance between the second location point and the first location point is determined to be less than or equal to the threshold value, the second location point is moved so that the three location points face one travel direction. , The reference position point, the first position point, the moved second position point and the third position point are A computer readable recording medium having recorded thereon a program for correcting hand shake caused when writing on an electronic blackboard using an electronic pen is executed.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

Correction of hand shake that occurs when writing on an electronic blackboard using an electronic pen according to an embodiment of the present invention can be implemented with the entire system shown in FIG. 3.

The entire system 10 includes an electronic blackboard 11 such as a tablet LCD monitor, an electronic pen 111 that performs writing such as writing or drawing on the electronic blackboard 11, and the electronic blackboard 11. Display the handwritten content processing device 12 for receiving and processing handwritten content including hand shaking generated when writing using the electronic pen 111 on the screen, and the signal processed by the handwritten content processing device 12 The display device 13 is formed.

The electronic blackboard 11 grasps the written contents such as writing letters or drawing pictures from the position of the electronic pen 111 as coordinates. Such an electronic blackboard includes a monitor-type electronic blackboard with a touch panel, an electronic blackboard using a tablet and a projector, and an electronic blackboard using a mouse. In embodiments of the present invention, the electronic blackboard is combined with an LCD monitor. Since an electronic blackboard in the form of a tablet is used, and writing or drawing using the electronic pen 111 as an input device is the same regardless of the type or form, any of the electronic blackboard may be used.

In this case, the writing surface of the copyboard 11 and the material characteristics of the electronic pen 111 may be slipped when writing, and the content of the writing may include a portion in which a small tremor of the hand or movement of the pen is reflected.

The handwriting content processing device 12 processes the handwritten content transmitted from the electronic blackboard 11 in real time, and the handwriting content processing unit 121 executes a control program stored in the memory unit 122 to prevent hand shake. A series of processes involving calibration are performed.

The display device 13 displays a signal for the handwritten content processed by the handwriting content processing device 12 including correction of hand shake through a liquid crystal projector or a separate electronic blackboard.

Referring to FIGS. 4 to 10, a process of compensating for hand shake that occurs when writing on an electronic blackboard using the electronic pen through the entire system described above is as follows.

Hand shake that occurs when writing on an electronic blackboard using the electronic pen according to an embodiment of the present invention is different from the progress direction when the electronic pen proceeds in one direction to write or draw on the electronic blackboard. Only in case of moving below a certain distance in the direction, it is judged and corrected.

As can be seen in the flowchart of FIG. 4, which shows the entire process of image stabilization, the writing content processing unit 121 executes a control program stored in the memory unit 122 to be used at an arbitrary reference time point. The reference position point Pо of the electronic pen 111 in use is specified, and three position points P ′, P 2, and P 3 specified at regular intervals after the reference time point are specified (S41). 5 illustrates an example in which four location points of the electronic pen recognized on the electronic blackboard are specified.

Next, the writing content processing unit 121 executes a control program stored in the memory unit 122 and calculates vector values up to three position points P₁, P₂ and P₃ based on the reference position point Pо (S42). ). Here, each of the vector values V₁, V₂ and V₃ are P₁ - is as Pо = V₃ = ┃V₃┃∠θ₃ - Pо = V₁ = ┃V₁┃∠θ₁, P₂ - Pо = V₂ = ┃V₂┃∠θ₂, P₃ .

Next, the writing content processing unit 121 executes a control program stored in the memory unit 122 to determine the distance between the second position point P2 and the first position point P₁, which are intermediate points of the three position points P₁, P₂ and P₃. It is determined whether the interval is less than the threshold (S43).

Here, the limit value represents the distance between the three position points P₁, P₂ and P₃, which varies depending on the characteristics of the device. The device for precisely transferring the pen position has a small threshold and the device for coarsely transmitting the pen position is There is a big limit.

It is generally appropriate to apply twice the minimum moving position of the electronic pen as the threshold, because if the threshold is too large, it may harm the detailed expression of the writing.

In other words, when the distance of the location point transmitted from the electronic pen is at least 0.5, the double 1 is set, and when the distance of the location point is at least 3, the limit is 6. However, when the minimum distance of the position point is 5 or more, since the hand shake is less likely to be transmitted to the electronic pen, it is determined that it is intended and is not used as the limit value.

If it is determined in step S43 that the threshold value is greater than or equal to the threshold value, the writing content processing unit 121 executes a control program stored in the memory unit 122 to execute the reference position point Pо of the electronic pen specified at an arbitrary reference time point, and the reference time point. After that, a curve is naturally formed between three location points P₁, P₂ and P₃ specified at regular intervals (S46).

However, if it is determined in step S43 that it is less than the threshold value, as shown in Fig. 6, in order to determine whether the second position point P2 out of the four position points specified above is out of the writing direction, the writing content processing unit The controller 121 executes a control program stored in the memory unit 122 to determine whether V2 is located within the allowable range between V ₁ and V ₃ and including the same (S44).

When the direction of travel of each location point is investigated for three location points P P, P₂ and P₃, the direction of the second location point P₂, which is an intermediate point, is different from that of the first location point P₁ and the third location point P₃. It is to judge whether it is going.

In general, when the direction of the vector in each vector value deviates by a certain angle, empirically about 7.5 ° or more, one of the points constituting the vector deviates from the reference point except for the reference point. In an embodiment of this invention it is V₂ consisting of the midpoint can be set within V₁ and position as an angle between V₃, or moving direction when it is located within the allowable range of V₁ and V₃ however, V₂ are to be located outside the allowable range of V₁ and V₃ It can be said that it is out of the direction of progress.

When it is determined in step S44 that V2 is located between V₁ and V₃ and within a predetermined allowable range including the same, the writing content processing unit 121 executes a control program stored in the memory unit 122 to execute an arbitrary reference time point. A reference position point Pо of the electronic pen specified in, forms a curve that naturally connects between the three position points P₁, P₂ and P₃ specified at regular intervals after the reference point (S46).

However, if it is determined that it is not located V₂ within a predetermined allowable range, at the step S44 comprising the same and between V₁ and V₃, the midpoint of both the front and the back to determine the second location point P₂ as the error that is caused by the hand tremor where By moving to the midpoint according to the position of points P₁ and P₃, the specified three position points P₁, P₂ and P₃ are directed in one direction so that natural writing is possible.

As can be seen in FIG. 7, which illustrates the movement of the intermediate point when the direction of writing is out of the judgment process of FIG. 6, the writing content processing unit 121 executes a control program stored in the memory unit 122. The second position point P₂ is moved to P₂ 'such that the three position points P 점, P₂ and P₃ are directed in one traveling direction (S45).

Specifically, in an embodiment of the present invention, since it is determined whether the second position point P₂ out of the four position points specified above is out of the writing progress direction, the second position point P₂ is determined from the second position point Pо in the second position point P 2. While maintaining the length ┃V₂┃ to the position point P₂, ┃∠θ₁-∠, which is the median value of the angle formed by the vector values obtained for the first position point P₁ and the third position point P₃ based on the reference position point Pо. Move to θ₃┃ / 2.

By moving the intermediate point, it is possible to eliminate or minimize the part not intended as writing.

Next, the curved process is performed to pass through a position point that is inflected to be naturally connected between the position points that have undergone the process of moving the second position point P₂, which is the midpoint of FIG. do.

These curves are calculated by equations, and given only a few position points, they naturally connect the points between them. In addition, since the curve connects the prediction points that naturally connect the points when the distance between them is farther away, the result can be more realistic than the actual handwriting. In a lesson, you can make a pen's trajectory a natural, smooth pen, like writing on paper.

In this way, the curve algorithm is applied in the embodiment of the present invention because the curve can best express the natural direction transition of the force applied to the pen at the time of the writing of the person, and obtain a result value close to the trajectory of the actual direction.

In general, unlike a straight line on a computer, a curve is not inferred by a simple equation. Moreover, in order to store and represent arbitrary curves on the computer, it is necessary to formulate and arrange them. Among the basic algorithms for expressing these curves, the Bezier algorithm requires that the characteristic of the curve must be within the curve. The two points always smooth this curve, always producing an accurate and smooth curve.

However, since the Bezier curve algorithm is directly connected to the number of control points and the order of the curve equation, the order of the curve is increased to generate a curve having a complicated shape, thereby increasing the amount of calculation. Also, the curve changes as a whole, even if you move any of the points that make up one patch, so the nature of the handwriting should be an independent part that should not change the previously drawn part. There is a limit.

The proposed method to solve this problem is the Bézier-spline (B-spline) curve algorithm. Since the B-spline curve algorithm affects only a certain range of each point, the B-spline curve algorithm can adjust only a desired part without changing the shape as a whole, which is shown in FIG. Indicates that the part drawn in is independent.

8 is a B-spline curve composed of a starting point V0 and an end point V5 and four control points V1, V2, V3, V4 and V5, each having a plurality of control points. Because of the limitations, even if you apply multiple control points to a patch, there is no difference in splitting between multiple patches.

As such, the B-spline curve is defined as in Equation 1 using the complementary blending function Ni, k (u).

In one embodiment of the present invention, the B-spline curve algorithm described and defined above is employed in curve processing so that the coordinates at the time of writing are used only to represent the corresponding area, and the formula is not complicated even if the control point is increased, so that the writing is not complicated. Even if there are several coordinates as inputs, the calculation efficiency can be increased by allowing them to be calculated and expressed at once.

Next, the writing content processing unit 121 executes a control program stored in the memory unit 122, so that the reference position point Pо, the first position point P ₁, and the moved two as shown in FIG. A curve is formed to naturally connect the first position point P₂ 'and the third position point P₃ (S46).

10A to 10C are shown successively so that each step of hand shake correction according to an embodiment of the present invention is easily understood.

In one embodiment of the present invention described above, first determine whether the sudden change in the handwriting is part of the handwriting or caused by the hand shake to adjust the coordinate value when the hand shake, and adjust the coordinates to be connected naturally Although curve processing is added, it can be simplified and processed as an approximate curve along a plurality of position points without adjustment of the intermediate coordinate value.

11A and 11B show the results of correcting hand shake by employing a B-spline curve algorithm according to another embodiment of the present invention for curve processing.

In addition, a computer-readable recording medium having recorded thereon a program for executing a method for correcting hand shake that occurs when writing on an electronic blackboard using an electronic pen according to an embodiment of the present invention is provided with a separate playback device (not shown). And the handwriting content processing device 12 as shown in the flowchart of FIG. 4.

The computer-readable recording medium which records the program for performing the above method of image stabilization includes optical recording media (CD, CD-R, CD-RW, DVD, etc.), floppy disk, hard disk, Zip disk, Floppy disks and the like. Furthermore, not only a computer-readable recording medium which records a program executable directly by a computer, but also a recording medium on which a program such as that which can be executed by installing on another recording medium (hard disk, etc.), is encrypted or compressed. It also includes a recording medium on which the recorded program is recorded and a storage medium such as a ROM or a RAM.

The present invention is not limited to the above embodiments, and various modifications are possible within the scope of the invention described in the claims, and such modifications are included in the scope of the present invention.

As described in detail above, according to the method for compensating for hand shake that occurs when writing on an electronic blackboard using the electronic pen of the present invention, a sudden change in writing can be made while maintaining the contents of continuous writing. The pen's trajectory, which is naturally connected from the coordinates, is alleviated with a nice curve that most closely resembles the actual pen movement.

Further, according to the method of compensating for hand shake that occurs when writing on an electronic blackboard using the electronic pen of the present invention and a computer-readable recording medium that records a program for executing the method, a sudden change in the writing is performed. It is judged as the direction and distance of movement, whether it is part of or caused by hand shake, and if it is a hand shake, it adjusts the coordinate value naturally to preserve the contents of continuous handwriting, and removes unintended parts as handwriting. While showing the trajectory of the pen that is naturally connected from the coordinates most similar to the actual pen movement, it is effective to mitigate the slight hand shake that appears according to the characteristics of the writing device into a curve that approximates the position of the coordinate.

Claims (6)

In the method of correcting the hand shake caused when writing on the copyboard using the electronic pen, An electronic pen, characterized in that the electronic pen is recognized as a position point of the electronic pen recognized on the electronic board, so that a plurality of position points specified at regular intervals after the reference time point are naturally connected to the reference position point specified at the reference time point. How to compensate for hand shake when writing on a copyboard. The method of claim 1, The curve processing for allowing the position points to be naturally connected is a method for correcting hand shake that occurs when writing on an electronic blackboard using an electronic pen, characterized by applying a Bezier-spline curve algorithm. The method of claim 1, Before the curve processing to allow the position points to be naturally connected, for the three position points specified at regular intervals after the reference time point based on the reference position point specified at the reference time point as the position point of the electronic pen recognized on the copyboard. From the obtained vector values, the second position of the three position points is traveling in a different direction than the first position point and the third position point, and the distance between the second position point and the first position point is less than the threshold. If it is determined that the second position point is moved so that the three position points face in one direction of travel, a method of compensating for hand shake occurring when writing on an electronic blackboard using an electronic pen. The method of claim 3, wherein Determination of the threshold value of the distance between the second position point and the first position point of the three position points, when writing on the electronic blackboard using the electronic pen, characterized in that twice the minimum moving distance of the electronic pen How to compensate for hand shake. The method of claim 3, wherein The second location point for directing the three location points in one travel direction is defined by the first location point relative to the reference location point while maintaining the length from the reference location point to the second location point. A method of compensating for hand shake that occurs when writing on an electronic blackboard using an electronic pen, characterized in that it moves to a median of an angle formed by vector values obtained for third position points. In order to compensate for hand shake that occurs when writing on the copyboard using the electronic pen, the computer is used as a position point of the electronic pen recognized on the copyboard. From the vector values obtained for each of the three location points specified at regular intervals, the second location point of the three location points is traveling in a different direction than the first location point and the third location point, and the second location If it is determined that the distance between the point and the first position point is less than the threshold, the second position point is moved so that the three position points face one traveling direction, and then the reference position point, the first position point, and the moved point are moved. Use the electronic pen to run the second position point and the third position point to be curved A computer-readable recording medium that records a program that compensates for camera shake when writing on an electronic board.