Page turn simulator

• US 5,053,762 A
• Filed: 04/28/1989
• Issued: 10/01/1991
• Est. Priority Date: 04/28/1989
• Status: Expired due to Term

• Current Assignee: Technology Licensing Corporation
• Original Assignee: Microtime, Inc. (Digital Fx, Inc.)
• Inventors: Sarra, Gene R.
• Primary Examiner(s): Brier, Jeffery A.
• Application Number:
  US07/345,082
• Time in Patent Office: 886 Days
• Field of Search: 340/721, 340/734, 340/723, 340/747, 358/182, 358/183, 358/22, 358/22 PIP
• US Class Current: 345/641
• CPC Class Codes: G09G 5/14 Display of multiple viewports
• CPC Class Codes: H04N 5/2628 Alteration of picture size, shape, position or orientation, e.g. zooming, rotation, rolling, perspective, translation

Abstract

An apparatus and method for simulating a partially turned page on a video screen using a combination of linear and nonlinear picture partitioning. Multiple variable boundary lines are defined for separating areas on the television screen in which different video signals are displayed representative of the front and back sides of a partially turned page. Circuitry is provided for switching between the video signal for the page being turned and a single-color signal depicting the back of the page being turned, as well as for selecting between a video signal for the page being turned and a video signal for the page being revealed. Additional circuitry is provided for simulating a warp in an image on a page due to the page being turned.

Claims

1. A method of simulating a page turning effect on a video screen having multiple scan lines, comprising the steps:

(a) defining in memory a plurality of sets of boundary lines, each set being representative of a different stage of progression of a turning page and including

(1) a first parabolic boundary line representative of a two-dimensional image of a partially turned lateral edge of said turning page;

(2) a second parabolic boundary line representative of a two-dimensional image of a partially turned top or bottom edge of said turning page; and

(3) a third boundary line representative of a fold of said turning page;

(b) reading said sets of boundary lines out of memory in succession;

(c) selecting among the first, second and third boundary lines of each set read from memory for each of a plurality of said scan lines on said video screen;

(d) calculating the intersection point of each selected boundary line on each scan line for which it is selected; and

(e) switching between first and second video sources in synchronism with line scanning, said synchronized switching step including, for each set of boundary liens read from memory, comparing current position on each particular scan line being scanned with each intersection point calculated for said particular scan line;

wherein said selecting step includes selecting said first and third boundary lines for a first subset of said plurality of scan lines and selecting said second and third boundary lines for a second subset of said plurality of said scan lines; and

wherein said switching step includes switching to said second video source for the portion of each of said plurality of scan lines located between the boundary lines in either of the pairs of boundary lines selected in said selecting step, whereby an image from said second video source is displayed on said video screen between said partially turned lateral edge, said partially turned top or bottom edge and said fold of said turning page so as to simulate an image on the back of said turning page.

2. The method of claim 1 further comprising the step of switching between said second video source and a third video source, in synchronism with line scanning, at the intersection point of said third boundary lien on each of said plurality of said scan lines on said video screen, thereby simulating a page partially revealed behind said turning page.

3. The method of claim 2 further comprising the step of selecting only said second parabolic boundary line for a third subset of said plurality of scan lines on said video screen;

wherein said switching step includes switching directly between said first and third video sources at each intersection point of said second parabolic boundary line on each scan line in said third subset of said plurality of said scan lines on said video screen, thereby simulating a direct transition between the front of said turning page and the page partially revealed behind said turning page at a portion of said partially turned top or bottom edge.

4. The method of claim 3 wherein said second parabolic boundary line is defined by two parabolas having a common vertex but different width coefficients, wherein one of said parabolas is representative of a two-dimensional image of said portion of said partially turned top or bottom edge and the other parabola is representative of a two-dimensional image of the remainder of said partially turned top or bottom edge of said turning page.

5. The method of claim 4 further comprising the step of warping video data to simulate a warped image near said fold on said turning page.

6. A page turn simulator for simulating a page turning effect on a video screen having multiple scan lines, comprising:

(a) means for defining in memory a plurality of sets of boundary lines, each set being representative of a different stage of progression of a turning page and including

(1) a first parabolic boundary line representative of a two-dimensional image of a partially turned lateral edge of said turning page;

(2) a second parabolic boundary line representative of a two-dimensional image of a partially turned top or bottom edge of said turning page; and

(3) a third boundary line representative of a fold of said turning page;

(b) means for reading said sets of boundary lines out of memory in succession;

(c) means for selecting among the first, second and third boundary lines of each set read form memory for each of a plurality of said scan lines on said video screen;

(d) means for calculating the intersection point of each selected boundary line on each scan line for which it is selected; and

(e) means for switching between first and second video sources in synchronism with line scanning, said synchronized switching means including means operative for each set of boundary lines read from memory for comparing current position on each particular scan line being scanned with each intersection point calculated for said particular scan line;

wherein said selecting means includes means for selecting said first and third boundary lines for a first subset of said plurality of scan lines and selecting said second and third boundary lines for a second subset of said plurality of said scan lines; and

wherein said switching means includes means for switching to said second video source for the portion of each of said plurality of scan lines located between the boundary lines in either of the pairs of boundary lines selected by said selecting means, whereby an image from said second video source is displayed on said video screen between said partially turned lateral edge, said partially turned top or bottom edge and said fold of said turning page so as to simulate an image on the back of said turing page.

7. The page turn simulator of claim 6 further comprising means for switching between said second video source and a third video source, in synchronism with line scanning, at the intersection point of said third boundary line on each of said plurality of said scan lines on said video screen, thereby simulating a page partially revealed behind said turning page.

8. The page turn simulator of claim 7 further comprising means for selecting only said second parabolic boundary line for a third subset of said plurality of scan lines on said video screen;

wherein said switching means includes means for switching directly between said first and third video sources at each intersection point of said second parabolic boundary line on each scan line in said third subset of said plurality of said scan lines on said video screen, thereby simulating a direct transition between the front of said turning page and the page partially revealed behind said turning page at a portion of said partially turned top or bottom edge.

9. The page turn simulator of claim 8 wherein said second parabolic boundary line is defined by two parabolas having a common vertex but different width coefficients, wherein one of said parabolas is representative of a two-dimensional image of said portion of said partially turned top or bottom edge and the other parabola is representative of a two-dimensional image of the remainder of said partially turned top or bottom edge of said turning page.

10. The page turn simulator of claim 9 further comprising means for warping video data to simulate a warped image near said fold on said turning page.