CN101739701A - Method for establishing painting brush sample library - Google Patents

Abstract

The invention relates to a method for establishing a painting brush sample library, which comprises the following steps: 1, scanning a picture drawn by a painting-characterized brush and inputting the acquired picture to a computer; 2, processing the input picture by the computer, including a step of acquiring an opacity picture and a paint thickness picture; and 3, establishing the painting brush sample library, wherein a storage structural table of each painting brush sample in the painting brush sample library at least comprises an input picture, an opacity picture of the picture and a paint thickness picture of the picture. By calling a painting simulated by the painting brush sample library which is established by the method, the third dimension of the style of the paining is greatly improved.

Description

Set up the method for painting brush sample library

Technical field

The present invention relates to technical field, be specifically related to style of writing analogy method, particularly set up the method for computer based painting brush sample library based on computing machine oil painting non-photorealistic rendering based on the computer drawing oil painting.

Background technology

The oil painting simulation is a kind of style that feeling of unreality is drawn analogue technique.The artistic style of non-photorealistic rendering analogue technique comprises sketch, watercolor, oil painting, traditional Chinese Painting, the light coloured silk of pen or the like.Current most existing research is primarily aimed at the simulation of artistic style material model, mainly comprise the interaction of physical model and the simulation style of writing and the paper of various styles of writing, paper, for example pencil model and Chinese brush model have been successfully applied to sketch, traditional Chinese Painting and watercolor, and have obtained simulate effect preferably.

The style of writing analogy method of computer based non-photorealistic rendering can roughly be divided into two big classes at present:

The first kind is based on the style of writing analogy method of physical parameter model, simulate effect better physical model comprises the light crayon model of pen, pencil model and watercolor pencil model etc., and these physical simulation styles of writing can the effect that render corresponding style true to nature in drawing process.

Second class is based on the style of writing analogy method of sample texture mapping model, mainly be traditional Chinese Painting Chinese brush model and skeleton style of writing model, the modelling of its Chinese painting a style of writing storehouse based on sample, shape, color and the textural characteristics of reflection traditional Chinese Painting style of writing that can be true to nature can reflect the traditional Chinese Painting effect really in computing machine.

In the style of writing model of present various styles, the simulation difficulty of painting style style of writing is maximum relatively, reason has 3 points: the firstth, and oil painting brush touch type not only comprises color and vein and shape information, also has an elevation information (mainly expressing the thickness information of oil painting stroke); The physical process that second profit mixes is relatively complicated, and the pigment thickness between the painting brush and color fusion ratio watercolor pencil model relative complex are a lot; The 3rd to be that paintbrush touches of a great variety, comprise scumbling, thickly be coated with, xerotripsis, loose be coated with, cover dye, cutter is scraped etc.

Summary of the invention

Technical matters to be solved by this invention is: a kind of method of setting up painting brush sample library is provided, and the painting brush sample library that this method provides is with the simulation painting style, thus the sense of reality of raising digital simulation oil painting.

The present invention is adopted solution to be by the problem of the above-mentioned proposition of solution:

Set up the method for painting brush sample library, it may further comprise the steps:

The picture that step (1), scanning oil painting feature brush are drawn and with the image input computing machine that obtains;

The step that step (2), computing machine are handled input picture, it comprises:

A, obtain the step of opacity figure and pigment thickness chart, be specially:

Step (A-1), input picture is handled, obtained the step of opacity figure;

Step (A-2), the step of calculating:

H(x，y)＝exp(-Alpha(x，y)*K)；

In the formula: 0＜K＜1; (x y) obtains each pixel among the opacity figure (x, brightness value y) for step (A-1) to Alpha;

(x is that the brightness value of each pixel is formed the pigment thickness chart y) with the H that obtains;

Step (3), set up the step of painting brush sample library;

At least comprise in the storage organization table of each painting brush sample in the painting brush sample library: the pigment thickness chart of the image of input, the opacity figure of this image, this image.

In the such scheme, step (2) also comprises:

B, obtain the step of binary map;

In the step (3), also comprise the binary map that this image obtains in the storage organization table of each painting brush sample in the painting brush sample library.

In the such scheme, the picture that described oil painting feature brush is drawn comprises at least: point-like brush picture, wire brush picture, block brush picture and texture brush picture.

The invention has the advantages that:

1, owing to comprises in the painting brush sample library that the inventive method is set up that (x is the brightness value composition pigment thickness chart and the opacity figure of each pixel y), calls the oil painting that painting brush sample library simulates, and its painting style sense of reality improves greatly by height field H.

2, the color diagram of scanning brush, purpose is the colouring information of distortionless storage brush, so that in calling the painting brush sample library process, can regenerate a brush with new color according to these colouring informations;

The opaque print picture of brush, this attribute can make to have degrees of fusion preferably between the brush;

The pigment height map of brush, the height of the actual brush of simulation that can be true to nature can reflect the stereoeffect of brush under light conditions;

The binary map of brush, purpose are the shape informations of storage brush.

When calling the painting brush sample library of the inventive method foundation, the operator can draw oil painting on computers according to the different styles of writing that different objects adopts, the style of writing that has more painting style that simulates can also make amendment to some parameters in the painting brush sample library in the process of drawing.

Description of drawings

Fig. 1 is the picture that oil painting feature brush definite among the inventive method embodiment is drawn

The painting brush sample library that Fig. 2 sets up for the inventive method embodiment

Fig. 3 is the style of writing that calls the painting style that the pigment height map in the painting brush sample library simulates

Embodiment

The present invention sets up the method embodiment of painting brush sample library, and it may further comprise the steps:

The picture that step (1), scanning oil painting feature brush are drawn and with the image input computing machine that obtains; The picture that described oil painting feature brush is drawn comprises at least: point-like brush picture, wire brush picture, block brush picture and texture brush picture.

The at first professional artist of this step draws the painting brush of different shape on clean blank sheet of paper, from the brush of drawing, choose the picture that 8 oil painting feature brushes are drawn then, according to the shape and the texture of brush these pictures are divided into four big classes: point-like brush (5), wire brush, block brush and texture brush (as shown in Figure 1).

The step that step (2), computing machine are handled input picture, it comprises:

A, obtain the step of opacity figure and pigment thickness chart, be specially:

Step (A-1), input picture is handled, obtained the step of opacity figure with Adobe Photoshop;

Step (A-2), the step of calculating:

H(x，y)＝exp(-Alpha(x，y)*K)；

In the formula: 0＜K＜1; (x y) obtains each pixel among the opacity figure (x, brightness value y) for step (A-1) to Alpha;

(x is that the brightness value of each pixel is formed the pigment thickness chart y) with the H that obtains;

B, input picture is handled, obtained the step of binary map with Adobe Photoshop;

Step (3), set up the step of painting brush sample library;

At least comprise in the storage organization table of each painting brush sample in the painting brush sample library: the binary map that the pigment thickness chart of the image of input, the opacity figure of this image, this image, this image obtain.

Painting brush sample library as shown in Figure 2, it comprises that (top 5 are point-like brush sample to the picture sample that 8 oil painting feature brushes draw, following 3 from left to right are respectively: wire brush sample, block brush sample and texture brush sample), each sample is respectively from top to bottom: the binary map that the pigment thickness chart of the image of input, the opacity figure of this image, this image, this image obtain.

In order to save storage space and to read painting brush sample library fast, the painting brush sample library storage format is as follows:

The image (three passages of RGB) of input

Opaque print (passage)

Pigment height map (passage)

Binary map (passage)

Here each passage is big or small identical, totally 6 passages.In order to draw fast the oil painting style of writing, when brush is stored, increased by six statistical informations in addition: the brush color on L α β space three passages (l, α, β) and mean square deviation (σ _l, σ _α, σ _β).

In actual drawing process, the brush in the painting brush sample library need just can be drawn through change color and altitude conversion, does being described in detail below respectively with regard to brush change color and height change.

The brush colour switching:

In drawing process, therefore the color of user-defined color or input picture need do colour switching to the color diagram in the painting brush sample library as the color of brush.In order to allow the brush after the change color keep the original texture properties of brush, the brush color diagram when the color converting algorithm based on L α β space below adopting obtains drawing.

Algorithm: based on the color converting algorithm in L α β space

1) (R, G B), are transformed into L α β space from rgb space non-white color C=on the brush color diagram.

$\left[\begin{array}{c}L\\ M\\ S\end{array}\right]=\left[\begin{array}{ccc}0.3811& 0.5783& 0.0402\\ 0.1967& 0.7244& 0.0782\\ 0.0241& 0.1288& 0.8444\end{array}\right]\left[\begin{array}{c}R\\ G\\ B\end{array}\right]$

L＝logL

M＝logM

S＝logS

$\left[\begin{array}{c}l\\ \mathrm{\α}\\ \mathrm{\β}\end{array}\right]=\left[\begin{array}{ccc}\frac{1}{\sqrt{3}}& 0& 0\\ 0& \frac{1}{\sqrt{6}}& 0\\ 0& 0& \frac{1}{\sqrt{2}}\end{array}\right]\left[\begin{array}{ccc}1& 1& 1\\ 1& 1& -2\\ 1& -1& 0\end{array}\right]\left[\begin{array}{c}L\\ M\\ S\end{array}\right]$

2) average of pixel each passage on L α β space of non-white on the statistics brush color diagram (l, α, β) and variance (σ _l ², σ _α ², σ _β ²).

$\stackrel{\‾}{l}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{l}_i,\stackrel{\‾}{\mathrm{\α}}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\α}}_i,\stackrel{\‾}{\mathrm{\β}}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\β}}_i$

${\mathrm{\σ}}_l^2=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(l_i-\stackrel{\‾}{l})}^2,{\mathrm{\σ}}_{\mathrm{\α}}^2=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{({\mathrm{\α}}_i-\stackrel{\‾}{\mathrm{\α}})}^2,{\mathrm{\σ}}_{\mathrm{\β}}^2=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{({\mathrm{\β}}_i-\stackrel{\‾}{\mathrm{\β}})}^2,$

3) with the color of object C of brush ₀=(R ₀, G ₀, B ₀) also be transformed into L α β space (L from rgb space ₀, α ₀, β ₀).

4) calculate each non-white pixel of brush at the new color (L in L α β space ^*, α ^*, β ^*)

${\mathrm{\α}}^{*}=\mathrm{\α}+\frac{\stackrel{\‾}{\mathrm{\α}}-\mathrm{\α}}{{\mathrm{\σ}}_{\mathrm{\α}}}$

${\mathrm{\β}}^{*}=\mathrm{\β}+\frac{\stackrel{\‾}{\mathrm{\β}}-\mathrm{\β}}{{\mathrm{\σ}}_{\mathrm{\β}}}$

$l^{*}={\mathrm{\β}}^{\′}+\frac{\stackrel{\‾}{l}-l}{{\mathrm{\σ}}_l}$

5) calculating pen refreshes color (L ^*, α ^*, β ^*) be transformed into rgb space from L α β space, obtain the figure as a result of change color.

$\left[\begin{array}{c}L\\ M\\ S\end{array}\right]=\left[\begin{array}{ccc}1& 1& 1\\ 1& 1& -1\\ 1& -2& 0\end{array}\right]\left[\begin{array}{ccc}\frac{\sqrt{3}}{3}& 0& 0\\ 0& \frac{\sqrt{6}}{6}& 0\\ 0& 0& \frac{\sqrt{2}}{2}\end{array}\right]\left[\begin{array}{c}l\\ \mathrm{\α}\\ \mathrm{\β}\end{array}\right]$

$\left[\begin{array}{c}R\\ G\\ B\end{array}\right]=\left[\begin{array}{ccc}4.4679& -3.5873& 0.1193\\ -1.2186& 2.3809& -0.1624\\ 0.0497& -0.2439& 1.2045\end{array}\right]\left[\begin{array}{c}L\\ M\\ S\end{array}\right]$

Adopt the Phong illumination model to play up, obtain the image (shown in Figure 3) that the simulated oil paintbrush touches height change.

The Phong illumination model comprises diffuse reflection, direct reflection, reflection of ambient light, and for the surface elevation field H of given brush, the computing formula of its illumination rending model is as follows:

$I_p=k_{\mathrm{\α}}{i}_{\mathrm{\α}}+\underset{\mathrm{lights}}{\mathrm{\Σ}}(k_d(L\·N)i_d+k_s{(R\·V)}^{\mathrm{\α}}{i}_s).$

K wherein _αBe the surround lighting coefficient, i _αIt is ambient light intensity; k _dBe diffuse-reflection factor, i _dIt is intensity; k _sBe specularity factor, i _sIt is the direct reflection light intensity; L is that incident angle of light R is the reflected light angle, and V is the observation angles of eyes in this position; Above parameter all can be revised, and N is brush surface height H (x, normal direction y).

After adopting the Phong illumination model to play up, the picture that obtains as shown in Figure 3, the figure on the left side among Fig. 3 is the pigment height map that calls in the painting brush sample library, the figure on the right is the style of writing figure of the painting style that simulates.

Claims (3)

1. set up the method for painting brush sample library, it is characterized in that: it may further comprise the steps:

The picture that step (1), scanning oil painting feature brush are drawn and with the image input computing machine that obtains;

The step that step (2), computing machine are handled input picture, it comprises:

A, obtain the step of opacity figure and pigment thickness chart, be specially:

Step (A-1), input picture is handled, obtained the step of opacity figure;

Step (A-2), the step of calculating:

H(x，y)＝exp(-Alpha(x，y)*K)；

In the formula: 0＜K＜1; (x y) obtains each pixel among the opacity figure (x, brightness value y) for step (A-1) to Alpha;

(x is that the brightness value of each pixel is formed the pigment thickness chart y) with the H that obtains;

Step (3), set up the step of painting brush sample library;

At least comprise in the storage organization table of each painting brush sample in the painting brush sample library: the pigment thickness chart of the image of input, the opacity figure of this image, this image.

2. the method for claim 1, it is characterized in that: step (2) also comprises:

B, obtain the step of binary map;

In the step (3), also comprise the binary map that this image obtains in the storage organization table of each painting brush sample in the painting brush sample library.

3. method as claimed in claim 1 or 2 is characterized in that: the picture that described oil painting feature brush is drawn comprises at least: point-like brush picture, wire brush picture, block brush picture and texture brush picture.

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