CN102289838A - Method for generating dynamic writing animation from calligraphy Chinese character image - Google Patents

Abstract

The invention relates to a method for generating a dynamic writing animation from a calligraphic Chinese character image, comprising the following steps: A), establishing at least one statistically-based standard stroke model; B), inputting the calligraphic Chinese character image and extracting the stroke outline of the Chinese character image; C), the user utilizes the digital board to interactively input the stroke motion trajectory of the calligraphy Chinese character in the stroke outline of the above-mentioned Chinese character image; D), calculates each trajectory point on the stroke motion trajectory of the user's input according to the above-mentioned standard stroke model selected by the user to form strokes; E), fill in the strokes formed by each track point in turn and save as each frame of the animation, and generate a video file. By adopting the above steps, the static calligraphic Chinese character image can be used as a dynamic writing animation to show the writing process of calligraphy, which can show the writing process of calligraphy very clearly, and is especially suitable for calligraphy teaching and the production of Chinese character writing animation for film and television media.

Description

A method for generating dynamic writing animations from calligraphy Chinese character images

technical field

The invention relates to a computer technology for digital image processing, in particular to a method for generating a dynamic writing animation from a calligraphic Chinese character image.

Background technique

Chinese calligraphy has high artistic appreciation value. After thousands of years of development, a large number of calligraphy inscriptions have been handed down in history. These calligraphy inscriptions presented in static images can no longer meet many current practical application needs, such as in film and television media and Chinese character writing animations widely used in the field of Chinese character application such as teaching Chinese as a foreign language. At present, most of them use flash eraser tools to manually produce Chinese character writing animations frame by frame. The disadvantages are that the production process is cumbersome, time-consuming and inefficient. However, reconstructing the animation of the writing process of calligraphy Chinese character images is a very challenging task, because: 1) During the long-term historical evolution of calligraphy, many calligraphy styles have been produced, such as common seal script, official script, regular script, cursive script, 2) In addition, even with the same calligraphy style, such as regular script, different calligraphers have different ways of using the brush (such as lifting, pressing, pause, frustration, and the combination of various strokes) Significant differences. The current methods of Chinese character recognition and image processing cannot automatically extract the strokes and writing traces of Chinese characters, which is why offline handwritten Chinese character recognition still has not made great progress.

Contents of the invention

In order to solve the technical problems in the prior art, the present invention provides a method for automatically generating an animation process of writing from static images of calligraphy Chinese characters, and dynamically displaying the writing process of Chinese calligraphy.

The present invention solves above-mentioned technical scheme, and the technical scheme provided is: provide a kind of method that generates its dynamic writing animation by calligraphy Chinese character image, comprise the following steps, A), set up at least one standard stroke model based on statistics; B), input calligraphy Chinese character image and extract the stroke outline of this Chinese character image; C), the user utilizes the digital board to interactively input the stroke movement trajectory of this calligraphy Chinese character in the stroke outline of the above-mentioned Chinese character image; D), calculate the user input according to the above-mentioned standard stroke model selected by the user The strokes formed by each track point on the stroke movement track; E), fill in the strokes formed by each track point in turn and save as each frame of the animation, and generate a video file.

As a preferred solution of the present invention, said step A) further includes the following steps, A1), collecting real brushstroke samples written on paper by different types of brushes; A2), counting the eigenvalues of the above-mentioned real brushstroke samples; A3), Combining the above eigenvalues, the parameter equations of the standard stroke models of different types of brushes are obtained respectively.

As a preferred solution of the present invention, said step B) further includes the following steps, B1), after inputting the calligraphic Chinese character image, black and white binary processing is carried out to the image; B2), utilizing the freeman chain code to extract the stroke outline of the Chinese character image.

As a preferred solution of the present invention, said step D) further includes the following steps, D1), calculating the four vertex coordinates of the standard stroke model of the current trajectory point according to each trajectory point information input by the user; D2), judging the current Are the coordinates of the four vertices of the locus point all within the stroke outline of the Chinese character image? If so, then proceed to step D4); if not, then proceed to step D3); D3), adjust the four vertex coordinates of the current track point so that it is located in the stroke outline of the Chinese character image, and the adjusted four vertex coordinates As the four vertex coordinates of the standard stroke model of the current track point; D4), according to the four vertex coordinates of the current track point, reverse the control point of the Bezier curve and generate the Bezier curve; D5), judge the generated Bezier curve Are the curves all within the outline of the strokes of the Chinese character image? If yes, then end; if not, proceed to step D6); D6), delete the part of the Bezier curves outside the stroke outline of the Chinese character image, replace it with the corresponding outline curve, and end.

in,

Brushstroke refers to the ink dots produced by the contact between the pen and the paper at a certain moment during the writing process of the brush;

The trajectory point of the writing process refers to the action point of the brush in the stroke;

The movement track of the stroke means that the above-mentioned track points constitute the movement trajectory of the stroke in the stippling, and the shape of the stipple in calligraphy can be regarded as composed of the sequence of strokes on the movement trajectory of the stroke.

Compared with the prior art, the technical solution of the present invention has the beneficial effects of:

(1) The static calligraphic Chinese character image is used as a dynamic writing animation to show the writing process of calligraphy, which is suitable for various calligraphy styles such as running script and cursive script, and can clearly show the writing process of calligraphy, especially suitable for calligraphy teaching and learning Animation production of Chinese character writing in the field of film and television media applications.

(2) After the user directly copies calligraphy and Chinese characters, he can watch the writing process of calligraphy through the generated animation frames or video files, and does not need to manually make animations of writing Chinese characters frame by frame, which improves work efficiency.

(3) According to the various standard strokes of the statistics, the same calligraphy can use different strokes to reflect the animation process of calligraphy, so that the animation can be displayed in a variety of ways.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is the flow chart of the method for generating its dynamic writing animation by calligraphy Chinese character images according to the present invention;

Fig. 2 is the flow chart of setting up the standard stroke model based on statistics according to the present invention;

Fig. 3 is the flow chart of inputting calligraphy Chinese character image and extracting the outline of this Chinese character image according to the present invention;

Fig. 4 is the flow chart of calculating the strokes formed by each track point on the stroke motion track input by the user according to the present invention;

Fig. 5 is the actual stroke shape of the brush collected according to the present invention;

Fig. 6 is the stroke shape of Bezier curve fitting of the present invention;

Fig. 7 is the black-and-white binary processing effect diagram of the image according to the present invention;

Fig. 8 is a graph of four stroke statistics according to the present invention.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Fig. 5 shows a schematic diagram of the real stroke shape of the brush. As shown in Figure 6, we found through observation that the shape of brush strokes can be fitted by two symmetrical three-degree Bezier (Bezier) curves up and down, and a standard stroke model can be established based on this. Based on this, the actual stroke shape can be defined as: S _f =(L _t , L _h , L _l , L _r ), where L _t , L _h , L _l , L _r are the feature values. L _t is the length of the tip of the pen, L _h is the length of the root of the pen, and L _l and L _r are the lengths of the left and right sides of the belly of the pen respectively. Under standard circumstances, L _l and L _r are equal in length and symmetrical, but during the writing process, the strokes are deformed due to the friction between the brush pen and the paper surface, so they are represented separately. The standard stroke model defined in this paper is shown on the right in Figure 5. The coordinate origin O is the corresponding position of the center of the brush holder, the abscissa x is the movement direction of the brush, and the four points T ₀ , T ₁ , T ₂ , T that intersect with the coordinate axes ₃ is the vertices of strokes, the distances from them to the origin O correspond to the characteristic values L _t , L _h , L _l , L _r of real strokes respectively.

的情况下，压感值P和笔毫长度L是线性正相关的；由于笔根长度较短、毛量密集，对压感值较不敏感，因此本文假定与压感值P直接相关的是笔锋长度L_t。由于不同种类毛笔的笔毫长度L(cm)、材质和毛量分布都有差别，在此定义笔锋长度L_t的计算公式如下：Based on calligraphy knowledge and writing experience, for the same brush, there is no deformation at the tip of the brush and the length of the brush does not exceed the pen length

In the case of , the pressure sensitivity value P and the pen length L are linearly positively correlated; because the root length of the pen is short and the hair is dense, it is less sensitive to the pressure sensitivity value, so this paper assumes that the pressure sensitivity value P is directly related to The stroke length L _t . Since the length L (cm), material and distribution of hair volume of different types of brushes are different, the formula for defining the length L _t of the brush tip is as follows:

${\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; P</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; \&rho;L</span>}$

Among them, P _max is the upper limit of the output pressure sensitivity value of the tablet, and ρ is the unit conversion coefficient (convert cm into screen pixels).

The method for generating a dynamic writing animation from a calligraphic Chinese character image according to the present invention will be described in detail below in conjunction with the accompanying drawings. As shown in Figure 1, the method includes the following steps:

Step A, establishing at least one standard stroke model based on statistics.

First, samples of real brush strokes written on paper with different types of brushes are collected. The collection process can be manual collection or collection with the help of computer means. Usually, when the length of the brush tip on the contact surface is the same, when writing with a soft brush, the deformation of the belly and root on both sides is larger than that of a harder brush; similarly, a brush with denser hair is also longer. Therefore, according to the above-mentioned characteristics of the brush, a standard stroke model is established.

Second, the feature values of the above-mentioned real stroke samples are counted. The material and hair volume distribution of the brush are mainly reflected in the ratio coefficient α between the root and the tip of the brush and the ratio coefficient β between the belly and the tip on both sides. Therefore, α and β can be used as the eigenvalues of real brush strokes, that is, α=L _h /L _t , β=L _l /L _t . Usually, when the length of the tip of the contact surface is the same, when writing with a soft brush, the deformation of the belly and root on both sides is larger than that of a harder brush; similarly, the L _h , L _l , L _r of a brush with denser hair longer.

Based on the above analysis of the characteristics of the brush material and hair volume distribution, this patent application selects four typical types of brushes: Changfeng Yanghao, Dalanghao, Zhonglanghao, Xiaolanghao, etc., but not limited thereto. As shown in Figure 7, the abscissa is L_t, the A curve is the change of L_h with L_t, the B curve is L_l, the change of L_r with L_t.

The above data show that there is a linear relationship between L _t , L _h , L _l , and L _r :

L _h =α*L _t

L _l ＝L _r ＝β*L _t

Finally, combining the above eigenvalues α and β, the parameter equations of the standard stroke models of different types of brushes are respectively obtained. The linear least squares fitting is performed on the data of the four types of brushes in Table 1, and the relationship parameters α and β of different types of brushes are obtained.

The following table 1 is a sample of parameters obtained through manual collection and computer statistical analysis:

Changfeng brush (cm) Big wolf hair (cm) Middle wolf hair (cm) Little wolf hair (cm) L 5.0 2.8 2.2 1.7 α 0.25496 0.43541 0.17273 0.46970 β 0.25954 0.46564 0.43455 0.57851

Table 1

According to this, the parameter equations of the four vertices of the standard stroke model can be obtained:

T _oy =T _1y =T _2x =T _3x =0

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; P</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; \&rho;L</span>}$

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; *</span>\frac{\mathrm{<span\; class="notranslate">\; P</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; \&rho;L</span>}$

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; *</span>\frac{\mathrm{<span\; class="notranslate">\; P</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; \&rho;L</span>}$

T _3y = -L _r = -T _2y

Step B, input a calligraphic Chinese character image and extract the stroke outline of the Chinese character image.

First, after inputting the calligraphy Chinese character image, the black and white binary processing is performed on the image. The effect of black and white binarization as shown in Figure 7. There may be various formats of the calligraphic Chinese character image, such as JPEG, JPG, BMP, GIF, etc., which are not limited here. In addition, the calligraphic Chinese character image is subjected to black and white binarization processing. The binarization of the image means that the gray value of the point on the image is 0 or 255, that is to say, the whole image presents an obvious black and white effect.

Secondly, the stroke outline of the Chinese character image is extracted by freeman chain code. The freeman chain code extraction contour processing technology itself is a prior art, and will not be repeated here.

In step C, the user inputs the stroke movement trajectory of the calligraphy Chinese character in the stroke outline of the above-mentioned Chinese character image.

The user can input the stroke movement trajectory of the calligraphy Chinese character in the stroke outline of the extracted Chinese character image with the help of the digital tablet. The tablet can sense the coordinates, pressure sensitivity value and time information of each track point during the writing process of the user. Various methods of moving the pen, such as the center, the reverse, the hook, the fold, the lift, and the case, can be determined according to the following methods:

Assuming that P _n is the trajectory point at the current moment, P _o is the trajectory point at the previous moment, and P _t is the trajectory point at the next moment, calculate the tangent angle θ (obtained from the slope κ) and the degree of pressure change at each trajectory point η:

$\mathrm{<span\; class="notranslate">\; \&kappa;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Pt</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; po</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}{\mathrm{<span\; class="notranslate">\; Pt</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; po</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; x</span>}}$

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; the\; tan</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; \&kappa;</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; or</span>}\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{<span\; class="notranslate">\; +</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Pn</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; po</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; p</span>}}{\mathrm{<span\; class="notranslate">\; Pn</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; po</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; p</span>}}$

内，可以判断此时的笔锋为中锋；若切线角度θ较大而压力变化程度η处于内，表示出现“逆锋”、“弯钩”、“折”等情况；若压力变化程度η较大则表示出现“提”、“按”的情况。The method of judging the current trajectory point by the tangent angle θ (obtained from the slope κ) and the degree of pressure change η: If the tangent angle θ and the degree of pressure change η are in a small range

, it can be judged that the stroke at this time is the center; if the tangent angle θ is large and the pressure change degree η is at Inside, it means that there are situations such as "reverse front", "hook" and "folding"; if the pressure change degree η is large, it means that there are situations of "lifting" and "pressing".

Step D, according to the above-mentioned standard stroke model selected by the user as the basic stroke shape of each trajectory point on the stroke movement trajectory input by the user, and then adjust it in combination with the outline.

First, calculate the four vertex coordinates of the standard stroke model of the current trajectory point according to the information of each trajectory point input by the user;

When the user interactively inputs the stroke trajectory, the tablet detects a trajectory point at a predetermined time frequency (such as 150ms), records the coordinates, pressure sensitivity value and time information of the trajectory point, and calculates the vertex coordinates with the above parametric equation.

Secondly, judge whether the four vertex coordinates of the current track point are all within the stroke outline of the Chinese character image? If not, then the four vertex coordinates are adjusted so that the four vertex coordinates are located in the stroke outline of the Chinese character image, and the adjusted vertex coordinates are used as the vertex coordinates of the current track point; if so, then no adjustment is required, directly used as Vertex coordinates of the current track point.

Again, according to the four vertex coordinates of the current trajectory point, reverse the Bezier curve control points and generate the Bezier curve; and judge whether the generated Bezier curves are all within the stroke outline of the Chinese character image; if not, then Bezier curves located outside the stroke outline of the Chinese character image are deleted and replaced with corresponding outline curves to form new stroke shapes.

The calculation method of the Bezier curve control point is: the parameter form of the 3rd Bezier curve is: B(t)＝P ₀ (1-t) ³ +3P ₁ t(1-t) ² +3P ₂ t ² (1 -t)+P ₃ t ³ , t∈[0,1], it has 4 control points (as shown in Figure 6): P ₀ , P ₁ , P ₂ , P ₃ , where P ₃ , P ₀ The coordinates coincide with those of T ₁ and T ₀ respectively. According to the properties of Bezier curve, the curve is tangent _to line segment P ₀ P ₁ at point P 0 and tangent to line segment P ₂ P ₃ at point P ₃ . In the same way, calculate the control points P ₀ , P' ₁ , P' ₂ , and P ₃ of another Bezier curve.

Step E, filling the stroke shape formed by the above track points and saving it as each frame of the animation to generate a video file. The color of filling can be black or other colors, it is not limited here. The format of the video file is not limited, such as AVI format, etc.

The foregoing description shows and describes preferred embodiments of the present invention, and as previously stated, it is to be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments but may be applied to various other embodiments. Combinations, modifications and circumstances, and can be modified within the scope of the inventive concept described herein, by the above teachings or by skill or knowledge in the relevant field. However, changes and changes made by those skilled in the art do not depart from the spirit and scope of the present invention, and should all be within the protection scope of the appended claims of the present invention.

Claims (4)

1. A method for generating dynamic writing animation from calligraphy Chinese character images is characterized by comprising the following steps,

A) establishing at least one standard stroke model based on statistics;

B) inputting a calligraphy Chinese character image and extracting a stroke contour of the Chinese character image;

C) the user interactively inputs the stroke tip motion trail of the calligraphy Chinese character in the stroke outline of the Chinese character image by using a digital board;

D) according to the standard stroke model selected by the user, the standard stroke model is used as the basic stroke shape of each track point on the stroke front motion trail input by the user, and then the standard stroke model is adjusted by combining the outline;

E) and sequentially filling the strokes formed by each track point, storing the strokes as each frame of the animation, and generating a video file.

2. The method of claim 1, wherein step A) further comprises the step of,

A1) collecting real brush touch samples written on paper by different types of writing brushes;

A2) counting the characteristic value of the real pen touch sample;

A3) and combining the characteristic values to respectively obtain the parameter equations of the standard brush stroke models of the different types of writing brushes.

3. The method of claim 1, wherein said step B) further comprises the step of,

B1) after inputting the calligraphy Chinese character image, performing black and white binarization processing on the image;

B2) and extracting stroke outlines of the Chinese character images by using a freeman chain code.

4. The method of claim 1, wherein said step D) further comprises the step of,

D1) calculating four vertex coordinates of the standard pen touch model of the current track point according to the standard pen touch model selected by the user and each track point information interactively input;

D2) judging whether the coordinates of four vertexes of the current track point are all in the stroke contour of the Chinese character image? If yes, go to step D4); if not, go to step D3);

D3) adjusting four vertex coordinates of the current track point to be positioned in the stroke contour of the Chinese character image, and taking the adjusted four vertex coordinates as the four vertex coordinates of the standard stroke model of the current track point;

D4) reversely solving Bezier curve control points according to the four vertex coordinates of the current track point and generating a Bezier curve;

D5) is it determined whether all of the generated bezier curves are located within the stroke contour of the chinese character image? If yes, ending; if not, go to step D6);

D6) and deleting the part of the Bezier curve outside the stroke contour of the Chinese character image, replacing the part of the Bezier curve with the corresponding contour curve, and ending.

Images