Method and apparatus for painting on a computer

• US 5,182,548 A
• Filed: 01/10/1990
• Issued: 01/26/1993
• Est. Priority Date: 01/10/1990
• Status: Expired due to Term

• Current Assignee: Open Invention Network LLC
• Original Assignee: Silicon Graphics Incorporated (Graphics Properties Holdings, Inc.)
• Inventors: Haeberli, Paul E.
• Primary Examiner(s): Brier, Jeffery A.
• Assistant Examiner(s): Liang, Regina
• Application Number:
  US07/464,025
• Time in Patent Office: 1,112 Days
• Field of Search: 340/701, 340/703, 340/706, 340/709, 364/521, 358/22, 395/118, 395/131, 395/141, 395/155
• US Class Current: 345/639
• CPC Class Codes: G06T 11/001 Texturing; Colouring; Generation of texture or colour inpainting G06T5/77

Abstract

A method and apparatus for painting in a computer controlled video display system is described. A current shape of a brush stroke is determined. A current direction of the brush stroke is determined. A current position is determined. A current color is set equal to a color at the current position. The step of drawing the brush image on the display comprises the steps of setting a color of the brush image equal to the current color, setting a position of the brush image equal to the current position, and setting a direction of the brush image equal to the current direction of the brush stroke.

Claims

1. A method of painting in a computer controlled video display system, comprising the steps of:

(a) determining a current shape of a brush stroke, wherein the brush stroke is a representation of an image to be displayed on the display system;

(b) determining a current direction of the brush stroke;

(c) determining a current position on a first image;

(d) setting a current size of the brush stroke based on a current velocity of the movement of a user-actuated input device;

(e) automatically setting a current color equal to a color at the current position on the first image; and

(f) placing a copy of a brush image into a second image, wherein the brush image has a same shape as the brush stroke, comprising the steps of;

(i) setting a color of the brush image equal to the current color;

(ii) setting a position of the brush image equal to the current position;

(iii) setting a direction of the brush image equal to the current direction of the brush stroke; and

(iv) setting a size of the brush image equal to the current size of the brush stroke.

(g) determining a next position of a brush stroke on the first image;

(h) setting an instantaneous velocity based on a distance between the current position and the next position;

(i) setting the current velocity equal to a sum of a weighted value of the current velocity and a weighted value of the instantaneous velocity;

(j) setting the current position equal to the next position;

(k) if a user wishes to continue to paint, then repeating steps (d) through (j).

2. A method of painting in a computer controlled video display system, comprising the steps of:

(a) determining a current position on a first image of a brush stroke, wherein the brush stroke is a representation of an image to be displayed on the display system;

(b) determining a current shape of the brush stroke;

(c) determining a current size of the brush stroke;

(d) determining a current direction of the brush stroke;

(e) initializing a current X direction value to one and initializing a current Y direction value to one;

(f) automatically setting a current color equal to a color of a pixel at the current position in the first image;

(g) determining a next position on a first image of a brush stroke;

(h) determining a distance (1) between a first X value of the current position and a second X value of the next position and (2) between a first Y value of the current position and a second Y value of the next position;

(i) if the sum of (1) a product of the current X direction value and the distance between the first and second X values and (2) a product of the current Y direction value and the distance between the first and second Y values is less than zero, then setting the current X direction value equal to the current X direction value multiplied by -1 and setting the current Y direction value equal to the current Y direction value multiplied by -1;

(j) setting the current X direction value equal to a sum of a weighted value of the current X direction value and the distance between the first and second X values;

(k) setting the current Y direction value equal to a sum of a weighted value of the current Y direction value and the distance between the first and second Y values;

(l) setting the current brush stroke direction equal to the arctangent of the current Y direction value divided by the current X direction value;

(m) placing a copy of a brush image into a second image, wherein the brush image has a same shape as the brush stroke, comprising the steps of;

(i) setting a color of the brush image equal to the current color;

(ii) setting a position of the brush image equal to the current position of the brush stroke;

(iii) setting a direction of the brush image equal to the current direction of the brush stroke; and

(iv) setting a size of the brush image equal to the current size of the brush stroke.

(n) setting the current position equal to the next position.

(o) if a user wishes to continue to paint, then repeating steps (f) through (n).

3. A method of painting in a computer controlled video display system, comprising the steps of:

(a) determining a current position on a first image of a brush stroke, wherein the brush stroke is a representation of an image to be displayed on the display system;

(b) determining a current shape of the brush stroke;

(c) determining a luminance value of a pixel residing at the current position in a second image;

(d) setting a current direction equal to a product of a maximum possible current direction value and the luminance value divided by a maximum possible luminance value;

(e) determining a current size of the brush stroke;

(f) automatically setting a current color equal to a color of the pixel at the current position in the first image; and

(g) placing a copy of a brush image into a second image, wherein the brush image has a same shape as the brush stroke, comprising the steps of;

(i) setting a color of the brush image equal to the current color;

(ii) setting a position of the brush image equal to the current position of the brush stroke;

(iii) setting a direction of the brush image equal to the current direction of the brush stroke; and

(iv) setting a size of the brush image equal to the current size of the brush stroke.

4. A method of painting in a computer controlled video display system, comprising the steps of:

(a) storing in a second image a blurred copy of a first image;

(b) computing the gradient of the second image by performing the following steps;

(i) automatically setting a first value equal to a color of a pixel one pixel down and one pixel to the left of position of a sampled pixel in the second image, a second value equal to a color of a pixel one pixel down and one pixel to the right of the position of the sampled pixel in the second image, a third value equal to a color of a pixel one pixel up and one pixel to the left of the position of the sampled pixel in the second image, and a fourth value equal to the color of a pixel one pixel up and one pixel to the right of the position of the sampled pixel in the second image;

(ii) setting a fifth value equal to a difference between the sum of the second and fourth values and the sum of the first and third values;

(iii) setting a sixth value equal to a difference between the sum of the third and fourth values and the sum of the first and second values;

(iv) setting a seventh value equal to the product of -1 and the arctangent of the fifth value divided by the sixth value;

(v) storing the seventh value in a third image in a location associated with the pixel position;

(vi) repeating the above steps (i) through (v) for each pixel of the second image, wherein upon each repetition the sampled pixel is another pixel of the second image;

(c) determining a current shape of the brush stroke, wherein the brush stroke is a representation of an image to be displayed on the display system;

(d) determining a current size of the brush stroke;

(e) determining a current position on a fourth image;

(f) determining a current direction of the brush stroke based upon the value stored in the current position in the third image;

(g) setting a current color equal to a color of the pixel at the current position in the fourth image; and

(h) placing a copy of a brush image into a fifth image, wherein the brush image has a same shape as the brush stroke, comprising the steps of;

(i) setting a color of the brush image equal to the current color;

(ii) setting a position of the brush image equal to the current position of the brush stroke;

(iii) setting a direction of the brush image equal to the current direction of the brush stroke; and

(iv) setting a size of the brush image equal to the current size of the brush stroke.