WO2013013485A1

WO2013013485A1 - Method and system for generating computer sketch image

Info

Publication number: WO2013013485A1
Application number: PCT/CN2011/084249
Authority: WO
Inventors: 李云夕; 黄静; 谢军波
Original assignee: 深圳市万兴软件有限公司
Priority date: 2011-07-26
Filing date: 2011-12-19
Publication date: 2013-01-31
Also published as: CN102332170B; CN102332170A

Abstract

Disclosed are a method and system for generating a computer sketch image, the method comprising: S1, receiving an image to be processed, and judging whether the image is a color image or a gray scale image, if the image is a color image, then executing step S2, and if the image is a gray scale image, then executing step S3; S2, converting the color image into a gray scale image; S3, setting the gray scale image as a background image layer; S4, reversing the phase of the gray scale image to obtain a reverse phase image; S5, performing minimum gray scale expansion processing on the reverse phase image, and setting the image having undergone the expansion processing as a foreground image layer; S6, blending the foreground image layer with the background image layer to obtain a sketch image. The sketch image generated by the technical solution of the present invention has a good sketch effect, eliminating the need for manual interactive operation during the entire generation process.

Description

Method and system for generating computer sketch drawing

Technical field

The present invention relates to image processing technologies, and in particular, to a method and system for generating computer sketches.

Background technique

Sketch is a kind of image stylization. The sketch in reality is a pencil-based medium, with lines to represent or the artistic form of the scene. Sketch can be divided into line structure painting and fine realistic sketch. Manually creating sketches requires the author to have a certain degree of artistic skills, so computer simulation of sketch painting has important application and entertainment value.

At present, in some image software, there is a function of sketch drawing generation. Such as Photoshop's sketch filter, but the sketch of the sketch created by Photoshop's own sketch filter operation is not good. Another method is to first extract the contour map of the image by using the edge detection operator, and then manually adjust the local edge detection parameters in the sliding window to correct the contour, and finally perform stylized line rendering on the generated contour to obtain the final line. painting. However, this method of generating sketches requires manual interaction.

technical problem

The technical problem to be solved by the present invention is that, in view of the above-mentioned existing sketch drawing generation technology, the defect that the sketch effect is not good and the manual interaction operation is required, and the method for generating the computer sketch drawing is provided, the sketch effect is good, and no manual interaction is needed. operating.

Technical solution

The technical solution adopted by the present invention to solve the technical problem thereof is to construct a computer sketch drawing generation method, which is characterized in that:

S1. Receiving an image to be processed, and determining whether the image is a color map or a grayscale image, if it is a color map, step S2 is performed; if it is a gray scale image, step S3 is performed;

S2. Converting the color map to a grayscale image;

S3. setting the grayscale image as a background layer;

S4. Inverting the grayscale image to obtain an inverted image;

S5. performing minimum gray scale expansion processing on the inverted image, and setting the image after the expansion processing as a foreground layer;

S6. Mixing the foreground layer and the background layer to obtain a sketch image.

In the generating method of the present invention, in the step S5, an N*N window including the current pixel point is opened, and the minimum gray level of all the pixel points in the N*N window is taken, and the minimum gray level is obtained. As the gray value after the current pixel dot expansion processing, where N≥2.

In the generating method of the present invention, in the step S6, the mixing processing is one of the following: brightening mixing processing, difference mixing processing, positive film blending processing, bright light mixing processing, linear subtraction Light blending and color dodging.

In the generating method of the present invention, in the step S2, the color map is converted into a grayscale image according to the following formula:

Y1 = 0.299*R + 0.587*G + 0.114*B

Where Y1 is the gray value of the current pixel of the grayscale image, and R, G, and B are the color values of the red, green, and blue channels of the current pixel of the color map, respectively.

Y2= (R*306 + G*601 + B*117 + 512) *1024

Where Y2 is the gray value of the current pixel of the grayscale image, and R, G, and B are the color values of the red, green, and blue channels of the current pixel of the color map, respectively.

In the generating method of the present invention, in the step S4, the grayscale image is inverted by the following formula to obtain an inverted image:

Y3 = 255–Y2

Where Y3 is the gray value of the current pixel of the inverted view.

The invention also constructs a computer sketch drawing generation system, comprising:

a receiving and determining module, configured to receive an image to be processed, and determine whether the image is a color map or a grayscale image;

a grayscale generation module for converting a color map into a grayscale image;

a background layer setting module, configured to set the grayscale image as a background layer;

An inverted image generation module, configured to invert the grayscale image to obtain an inverted image;

An expansion processing module, configured to perform minimum grayscale expansion processing on the inverted image, and set the image after the expansion processing as a foreground layer;

A mixing processing module is configured to perform mixing processing on the foreground layer and the background layer to obtain a sketch image.

In the generating system of the present invention, the mixing process is one of the following: brightening mixing processing, difference mixing processing, positive film mixing processing, bright light mixing processing, linear lightening mixing processing, color lightening Mixed processing.

In the generating system of the present invention, the grayscale generating module converts the color map into a grayscale image according to the following formula:

Y1 = 0.299*R + 0.587*G + 0.114*B

In the generating system of the present invention, the expansion processing performed by the expansion processing module is: opening an N*N window including a current pixel point, taking a minimum gray scale of all pixel points in the N*N window, and The minimum gradation is used as the gradation value after the current pixel is expanded, where N ≥ 2.

Beneficial effect

By implementing the technical solution of the present invention, the generation of the sketch image is completed based on the mathematical morphology, the generation process is simpler than the prior art, the implementation efficiency is higher, the sketch effect of the generated sketch image is good, and the whole generation process does not require manual Interaction.

DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

1 is a flow chart of an embodiment of a method for generating a computer sketch drawing of the present invention;

Figure 2A is an image to be processed;

2B is a sketch image generated by the process of FIG. 2A using a computer sketch drawing generation method according to an embodiment of the present invention;

Figure 3A is another image to be processed;

FIG. 3B is a sketch image generated by the process of FIG. 3A using a computer sketch drawing generation method according to an embodiment of the present invention; FIG.

4 is a logical structural diagram of an embodiment of a computer sketch drawing generation system of the present invention.

Embodiments of the invention

As shown in FIG. 1, in the flowchart of the embodiment of the method for generating computer sketches of the present invention, the generating method includes steps S1-S6, which are specifically described below.

In step S1, the image to be processed is received, and it is determined whether the image is a color map or a grayscale image. If it is a color map, step S2 is performed; if it is a grayscale image, step S3 is performed. In step S2, the color map is converted into a grayscale image. In one example, the color map can be converted to a grayscale image according to the following formula:

Y1 = 0.299*R + 0.587*G + 0.114*B

Where Y1 is the gray value of the current pixel of the grayscale image, and R, G, and B are the color values of the red, green, and blue channels of the current pixel of the color map, respectively. It should be noted here that the image processing in this application is performed pixel by pixel. Preferably, in order to achieve a fast operation on the computer, the formula of the gray value of the current pixel point of the obtained grayscale image can be rewritten as:

Y2= (R*306 + G*601 + B*117 + 512) *1024

Where Y2 is the gray value of the current pixel of the grayscale image, and R, G, and B are the color values of the red, green, and blue channels of the current pixel of the color map, respectively. In step S3, the grayscale image is set as a background layer. In step S4, for example, the grayscale image is inverted by the following formula to obtain an inverted image:

Y3 = 255–Y2

Where Y3 is the gray value of the current pixel of the inverted view. In the step S5, the minimum gray scale expansion process is performed on the inverted image, and the image after the expansion process is set as the foreground layer. This step can be implemented by: opening a current pixel point. The N*N window takes the minimum gray level of all the pixels in the N*N window, and takes the minimum gray level as the gray value after the current pixel point is expanded, where N≥2, for example, the opened window If it is 3*3, and the current pixel is the center pixel, the gray value after the current pixel expansion process can be obtained by the following operation:

Y4(i, j) = min( min(Y3(i-1, j-1), Y3(i, j-1), Y3(i+1, j-1)),

Min(Y3(i-1, j), Y3(i, j), Y3(i+1, j)),

Min(Y3(i-1, j+1), Y3(i, j+1), Y3(i+1, j+1)))

Where Y4(i, j) is the gray value after the current pixel expansion process, Y3(i, j) is the gray value of the current pixel of the inverted view, that is, the gray value before the current pixel expansion process, Y3(i-1, j-1), Y3(i, j-1), Y3( i+1, j-1), Y3 (i-1, j), Y3(i+1, j), Y3(i-1, j+1), Y3(i, j+1), Y3(i+1, j+1) are respectively associated with Y3(i, j) The gray value of the nearest pixel. Through the above operation, the minimum gray level of 9 pixels in the window is obtained. In step S6, the foreground layer and the background layer are mixed to obtain a sketch image, and the mixing process may select any one of the following: brightening mixing processing, difference mixing processing, and multi-layer folding The mixing process, the bright light mixing process, the linear dodge mixing process, and the color dodge mixing process are preferred, and a color dodge mixing process is preferred. The color dodge blending operation can be calculated by the following program:

If(Front == 255)

{

Y5 = 255;

}

Else

{

Y5 = min(255, (Back * 256 ) / (255-Front));

}

Y5 is the gray value of the current pixel on the mixed result image, Front is the gray value of the current pixel on the foreground layer, and Back is the gray value of the current pixel on the background layer.

2A is a to-be-processed image, which is a landscape image, and FIG. 2B is a sketch image generated by the process of FIG. 2A using the above-described computer sketching generation method, and in the generation method, a linear subtraction is adopted. Mixed processing. 3A is another image to be processed, the image is a person image, and FIG. 3B is a sketch image generated by the process of FIG. 3A using the above-described computer sketch drawing generation method, and in the generation method, the color is lightened. Mixed processing. Comparing FIGS. 2A and 2B, and FIGS. 3A and 3B, it can be seen that the sketch effect of the generated sketch image is good, and the entire generation process does not require manual interaction.

4 is a logical structural diagram of an embodiment of a computer sketch drawing generation system of the present invention. The generation system includes: a receiving and determining module 11, a grayscale generating module 12, a background layer setting module 13, and an inverted image generating module 14, The expansion processing module 15 and the mixing processing module 16. The receiving and determining module 11 is configured to receive the processed image, and determine whether the image is a color map or a grayscale image; the grayscale graph generating module 12 is configured to convert the color map into a grayscale image; the background layer setting module 13 is used to set the grayscale image as a background layer; the inverse image generation module 14 is configured to invert the grayscale image to obtain an inverted image; and the expansion processing module 15 is configured to minimize the inverted image The value gray scale expansion process is performed, and the image after the expansion processing is set as the foreground layer; the mixing processing module 16 is configured to perform mixing processing on the foreground layer and the background layer to obtain a sketch image.

In the mixing processing module 16 of the above embodiment, the mixing processing may be one of the following: brightening mixing processing, difference mixing processing, positive film mixing processing, bright light mixing processing, linear lightening mixing processing, color lightening A mixing process in which a color lightening mixing process is preferred.

In the expansion processing module 15 of the above embodiment, the expansion processing is: opening an N*N window including the current pixel point, taking the minimum gray level of all the pixel points in the N*N window, and taking the minimum gray level. As the gray value after the current pixel dot expansion processing, where N≥2.

In the grayscale map generation module 12 of one embodiment, the color map is converted to a grayscale map according to the following formula:

Y1 = 0.299*R + 0.587*G + 0.114*B

In another embodiment of the grayscale map generation module 12, the color map can also be converted to a grayscale map according to the following formula:

Y2= (R*306 + G*601 + B*117 + 512) *1024

Where Y2 is the gray value of the current pixel of the grayscale image, and R, G, and B are the color values of the red, green, and blue channels of the current pixel of the color map, respectively. This speeds up the computer's computing speed.

The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. within the spirit and scope of the invention are intended to be included within the scope of the appended claims.

Claims

A method for generating a computer sketch drawing, comprising:

S1. Receiving an image to be processed, and determining whether the image is a color map or a grayscale image, if it is a color map, step S2 is performed; if it is a gray scale image, step S3 is performed;

S2. Converting the color map to a grayscale image;

S3. setting the grayscale image as a background layer;

S4. Inverting the grayscale image to obtain an inverted image;

S5. performing minimum gray scale expansion processing on the inverted image, and setting the image after the expansion processing as a foreground layer;

S6. Mixing the foreground layer and the background layer to obtain a sketch image.
The generating method according to claim 1, wherein in the step S5, an N*N window including a current pixel point is opened, and a minimum gray level of all pixels in the N*N window is taken, and The minimum gray scale is used as the gray value after the current pixel point expansion processing, where N≥2.
The generating method according to claim 1 or 2, wherein in the step S6, the mixing processing is one of the following: a brightening mixing process, a difference mixing process, a positive film bottom mixing process, Bright blending process, linear dodge blending process, and color dodge blending process.
The generating method according to claim 1 or 2, wherein in the step S2, the color map is converted into a grayscale image according to the following formula:

Y1 = 0.299*R + 0.587*G + 0.114*B

Where Y1 is the gray value of the current pixel of the grayscale image, and R, G, and B are the color values of the red, green, and blue channels of the current pixel of the color map, respectively.
The generating method according to claim 1 or 2, wherein in the step S2, the color map is converted into a grayscale image according to the following formula:

Y2= (R*306 + G*601 + B*117 + 512) *1024

Where Y2 is the gray value of the current pixel of the grayscale image, and R, G, and B are the color values of the red, green, and blue channels of the current pixel of the color map, respectively.
The generating method according to claim 5, wherein in the step S4, the grayscale image is inverted by the following formula to obtain an inverted image:

Y3 = 255–Y2

Where Y3 is the gray value of the current pixel of the inverted view.
A computer sketch drawing generation system, comprising:

a receiving and determining module, configured to receive an image to be processed, and determine whether the image is a color map or a grayscale image;

a grayscale generation module for converting a color map into a grayscale image;

a background layer setting module, configured to set the grayscale image as a background layer;

An inverted image generation module, configured to invert the grayscale image to obtain an inverted image;

An expansion processing module, configured to perform minimum grayscale expansion processing on the inverted image, and set the image after the expansion processing as a foreground layer;

A mixing processing module is configured to perform mixing processing on the foreground layer and the background layer to obtain a sketch image.
The generating system according to claim 7, wherein the mixing processing is one of the following: a brightening mixing process, a difference mixing process, a positive film bottom mixing process, a bright light mixing process, and a linear lightening mixing process. , color lightening mixed processing.
The generating system according to claim 7, wherein said grayscale generating module converts the color map into a grayscale image according to the following formula:

Y1 = 0.299*R + 0.587*G + 0.114*B

Where Y1 is the gray value of the current pixel of the grayscale image, and R, G, and B are the color values of the red, green, and blue channels of the current pixel of the color map, respectively.
A generating system according to any one of claims 7-9, characterized in that The expansion processing performed by the expansion processing module is: opening an N*N window including the current pixel point, taking the minimum gray level of all the pixel points in the N*N window, and expanding the minimum gray level as the current pixel point. The processed gray value, where N ≥ 2.