Method and system for generating an image having a hand-painted appearance

• US 6,011,536 A
• Filed: 05/22/1998
• Issued: 01/04/2000
• Est. Priority Date: 04/17/1998
• Status: Expired due to Term

• Current Assignee: New York University
• Original Assignee: New York University
• Inventors: Hertzmann, Aaron P., Perlin, Kenneth
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Laneau, Ronald
• Application Number:
  US09/083,401
• Time in Patent Office: 592 Days
• Field of Search: 345/112, 345/156, 345/419, 345/431
• US Class Current: 345/418
• CPC Class Codes: B44F 11/02 Imitation of pictures, e.g. oil paintings
• CPC Class Codes: G06T 11/001 Texturing; Colouring; Generation of texture or colour inpainting G06T5/77

Abstract

A method and system receives a digital source image and brush size data. The source image is blurred to generate a digital reference image. The brush size data includes a first record corresponding to a first size of a brush and a second record corresponding to a second size of the brush. The first size is different from the second size. The method and system applies brush strokes, with the first record to be used for the brush, to a digital canvas image using the reference image. Then the brush strokes are applied, with the second record to be used for the brush, to the canvas image using the reference and working images. Thus, a final digital image having a hand-painted appearance is generated on the canvas image. Long curved brush strokes can also be used to generate the target image, which is aligned in a normal direction to image gradients. Furthermore the graphic artist may adjust parameters of the method and system according to the present invention to vary the style of painting.

Claims

1. A method for generating a digital finalized image having a hand-painted appearance on a digital canvas image using a computer system, the method comprising the steps of:

(a) receiving a digital source image;

(b) blurring the source image to generate a digital reference image;

(c) receiving brush size data, the brush size data including a first record corresponding to a first size of a brush and a second record corresponding to a second size of the brush, the first size being different from the second size;

(d) with the first record for the brush, applying brush strokes to the canvas image using the reference image; and

(e) with the second record for the brush and after step (d), applying the brush strokes to the canvas image using the reference and canvas images.

2. The method according to claim 1, further comprising the step of:

(f) displaying the canvas image on a display device.

3. The method according to claim 1, further comprising the step of:

(f) storing the canvas image using in a storage device.

4. The method according to claim 1, wherein the first size of the brush is greater than the second size of the brush.

5. The method according to claim 4, wherein the brush size data includes a third record corresponding to a third size of the brush, the third size being smaller than the second size, and further comprising the step of:

(g) with the third record for the brush and after step (e), applying the brush strokes to the canvas image using the reference and canvas images.

6. The method according to claim 1, wherein step (d) includes the substeps of:

(i) overlaying a grid over the canvas image to generate grid locations, and

(ii) applying the brush strokes in a current location of the grid locations.

7. The method according to claim 6, wherein the brush strokes are applied in a direction being normal to a gradient of the current location.

8. The method according to claim 1, wherein step (e) includes the substeps of:

(i) overlaying a grid over the canvas image to generate grid locations,

(ii) comparing the canvas image and the reference image to generate difference values for each of the grid locations,

(iii) averaging the difference values of the difference locations around a current location to generate an averaged value,

(iv) determining a further location having a highest difference value, and

(v) applying the brush strokes in the further location if the averaged value is greater than a threshold value.

9. The method according to claim 8, wherein the brush strokes are applied in a direction being normal to a gradient of the further location.

10. The method according to claim 8, wherein the substep (v) includes the substeps of:

(v1) determining a first difference between a color of the reference image at the further location and a current color of the canvas image at the further location,

(v2) determining a second difference between a first color of the corresponding location and a second color of the brush stroke, and

(v3) continuing a curved brush stroke having a stroke length to another location on the canvas image if one of;

the stroke length is smaller than a maximum stroke length, and

the stroke length is larger than a minimum stroke length and the first difference is greater than the second difference.

11. The method according to claim 10, wherein the substep (v) further includes the substep of:

(v4) filtering a curvature of the curved brush stroke.

12. The method according to claim 1, further comprising the step of:

(g) receiving style data, wherein the brush strokes are applied to the canvas image using the style data.

13. The method according to claim 1, wherein step (d) includes the substep of:

storing each of the brush strokes in a list.

14. The method according to claim 1, wherein step (e) includes the substep of:

storing each of the brush strokes in a list.

15. A system for generating a digital image having a hand-painted appearance on a canvas image, comprising:

a device providing a source image and brush size data; and

a processor blurring the source image to generate a reference image and receiving the brush size data, the brush size data including a first record corresponding to a first size of a brush and a second record corresponding to a second size of the brush, the first size being different from the second size,

wherein the processor, with the first record for the brush, applies brush strokes to the canvas image using the reference image to generate a working image, and

wherein the processor, with the second record for the brush, applies the brush strokes to the working image using the reference and working images to generate a finalized image.

16. The system according to claim 15, further comprising:

a display device displaying the finalized image.

17. The system according to claim 15, further comprising:

a storage device storing the finalized image.

18. The system according to claim 15, wherein the first size of the brush is greater than the second size of the brush.

19. The system according to claim 18, wherein the brush size data includes a third record corresponding to a third size of the brush, the third size being smaller than the second size, and wherein the processor, with the third record for the brush, applies the brush strokes to the finalized image using the reference and finalized images to generate a final image.

20. The system according to claim 15, wherein the processor applies the brush strokes to the canvas image by overlaying a grid over the canvas image to generate grid locations, and by applying the brush strokes in a current location of the grid locations.

21. The system according to claim 20, wherein the brush strokes are applied in a direction being normal to a gradient of the current location.

22. The system according to claim 15, wherein the processor applies the brush strokes over the working image by:

(a) overlaying a grid over the finalized image to generate grid locations,

(b) comparing the finalized image and the reference image to generate difference values for each of the grid locations,

(c) averaging the difference values of the difference locations around a current location to generate an averaged value,

(d) determining a further location having a highest difference value,

(e) generating control points in the further location if the averaged value is greater than a threshold value;

(f) connecting the control points to form the brush strokes.

23. The system according to claim 22, wherein the brush strokes are applied in a direction being normal to a gradient of the further location.

24. The system according to claim 22, wherein the processor applies the brush stroke in the further location by:

(a) determining a first difference between the further location and a corresponding location on the reference image,

(b) determining a second difference between a first color of the corresponding location and a second color of the brush strokes, and

(c) continuing a curved brush stroke having a stroke length to the further location on the finalized image if one of;

the stroke length is smaller than a maximum stroke length, and

the stroke length is larger than a minimum stroke length and the first difference is greater than the second difference.

25. The system according to claim 24, wherein the processor applies the brush stroke in the further location by:

(d) filtering a curvature of the curved brush stroke.

26. The system according to claim 24, wherein the brush strokes are applied to the canvas image using the style data.

27. The system according to claim 15, wherein the processor applies the brush strokes over the canvas image by:

storing each of the brush strokes in a list.

28. The system according to claim 15, wherein the processor applies the brush strokes over the working image by:

storing each of the brush strokes in a list.