System and method for scaling combined video and computer generated imagery

• US 6,424,749 B1
• Filed: 03/30/1999
• Issued: 07/23/2002
• Est. Priority Date: 03/30/1999
• Status: Expired due to Term

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Zhu, Daniel Qiang, Stec, Kevin John
• Primary Examiner(s): ROGERS, SCOTT A
• Application Number:
  US09/281,554
• Time in Patent Office: 1,211 Days
• Field of Search: 382/260, 382/275, 382/279, 382/298, 382/300, 345/611, 345/615, 345/629, 345/632, 348/441, 348/552
• US Class Current: 382/260
• CPC Class Codes: G06T 3/403 Edge-driven scaling; Edge-based scaling

Abstract

A system and method for format conversion for use with images containing mixed video and computer generated imagery. A first intermediate scaled image is generated using a first interpolator which has a relatively wide passband and a narrow transition band to the stop band. This interpolator retains high frequency components in the interpolated image but may introduce ringing distortion adjacent to strong edges. The first intermediate scaled image is then processed through an edge extractor which extracts strong edges but ignores any associated ringing distortion. The output signal of the edge detector is a scaled edge image. Next, a second intermediate scaled image is generated using a second interpolator which has a narrower passband and a more gradual transition band. This interpolator produces an image having reduced high frequency components relative to the original image. Then the scaled edge image is added to the second ma intermediate scaled image to produce a converted image having substantially the same high frequency components as the first intermediate scaled image but no ringing distortion components.

Claims

1. A method for scaling an input image which includes both video and computer generated image components, comprising the steps of:

a) generating a first intermediate scaled image by processing the input image with a first frequency response characteristic that has a passband and a stop band and a transition band between the passband and the stop band;

b) processing the first intermediate scaled image to extract a scaled edge image therefrom;

c) generating a second intermediate scaled image by processing the input image with a second frequency response characteristic that has a passband and a stop band and a transition band between the passband and the stop band, the transition band of the second frequency response characteristic being more gradual than the transition band of the first frequency response characteristic; and

d) adding the scaled edge image to the second intermediate scaled image to produce the output image.

2. A method according to claim 1, wherein:

the step of generating the first intermediate scaled image includes the step of convolving the input image with a Kaiser windowed sinc function; and

the step of generating the second intermediate scaled image includes the step of convolving the input image with a truncated raised cosine function.

3. A method according to claim 1, wherein the step of processing the first intermediate scaled image to extract a scaled edge image therefrom includes the step of processing the first intermediate scaled image through a Marr filter.

4. A method according to claim 1, wherein the input image is a two-dimensional (2-D) image and the step of generating the first scaled image includes the steps of:

processing the input image with a first one-dimensional (1-D) frequency response characteristic to produce a horizontally filtered image;

transposing the horizontally filtered image; and

processing the transposed horizontally filtered image with the 1-D frequency response characteristic to produce a horizontally and vertically filtered image;

wherein the 1-D frequency response characteristic has the passband, transition band and stop band of the first frequency response characteristic.

5. A system for scaling an input image which includes both video and computer generated imagery, comprising:

a) a first interpolator having a frequency response characteristic which defines a passband, a stop band and a transition band between the passband and the stop band for processing the input image to produce a first intermediate scaled image;

b) an edge extractor which processes the first intermediate scaled image to extract a scaled edge image therefrom;

c) a second interpolator having a frequency response characteristic which defines a passband, a stop band and a transition band between the passband and the stop band for processing the input image to produce a second intermediate scaled image, wherein the transition band of the second interpolator is more gradual than the transition band of the first interpolator; and

d) an adder for adding the scaled edge image to the second intermediate scaled image.

6. A system according to claim 5, wherein the frequency response characteristic of the first interpolator is a third-order frequency response characteristic.

7. A system according to claim 6, wherein the first interpolator is a Kaiser windowed sinc Interpolator, the second interpolator is a raised-cosine interpolator.

8. A system according to claim 7, wherein the edge extractor is a Marr filter.

9. A system according to claim 5, wherein the input image is a two-dimensional (2-D) image defined by a sequence of horizontal lines of samples, and the first interpolator includes:

a first one-dimensional (1-D) interpolator which processes the input image to generate a horizontally filtered image;

a transpose memory coupled to receive the horizontally filtered image and to provide the horizontally filtered image as a sequence of vertical lines of samples;

a second 1-D interpolator which processes the horizontally filtered image provided by the transpose memory to produce a horizontally and vertically filtered image; and

a second transpose memory coupled to receive the horizontally and vertically filtered image as a sequence of vertical lines of samples and to provide the horizontally and vertically filtered image as a sequence of horizontal lines of samples.

10. A system for scaling an input image which includes both video and computer generated imagery, comprising:

a) a first interpolator having an input port coupled to receive the input image and an output port, the first interpolator having a frequency response characteristic which defines a passband, a stop band and a transition band between the passband and the stop band;

b) an edge extractor having an input port and an output port, the input port being coupled to the output port of the first interpolator;

c) a second interpolator having an input port coupled to receive the input image and an output port, the second interpolator having a frequency response characteristic which defines a passband, a stop band and a transition band between the passband and the stop band, wherein the transition band of the second interpolator is more gradual than the transition band of the first interpolator; and

d) an adder for adding having a first input port coupled to the output port of the edge extractor and a second input port coupled to the output port of the second interpolator.

11. A system according to claim 10, wherein:

the first interpolator is a Kaiser windowed sinc interpolator;

the second interpolator is a raised cosine interpolator; and

the edge extractor is a Marr filter.

12. A carrier encoded with a computer program which, when executed causes a computer to scale an input image which includes both video and computer generated image components, the computer program causing the computer to perform the steps of:

a) generating a first intermediate scaled image by processing the input image with a first frequency response characteristic that has a passband and a stop band and a transition band between the passband and the stop band;

b) processing the first intermediate scaled image to extract a scaled edge image therefrom;

c) generating a second intermediate scaled image by processing the input image with a second frequency response characteristic that has a passband and a stop band and a transition band between the passband and the stop band, the transition band of the second frequency response characteristic being more gradual than the transition band of the first frequency response characteristic; and

d) adding the scaled edge image to the second intermediate scaled image to produce the output image.

13. A carrier according to claim 12, wherein the input image is a two-dimensional (2-D) image and the step of generating the first scaled image includes the steps of:

processing the input image with a first one-dimensional (1-D) frequency response characteristic to produce a horizontally filtered image;

transposing the horizontally filtered image; and

processing the transposed horizontally filtered image with the 1-D frequency response characteristic to produce a horizontally and vertically filtered image;

wherein the 1-D frequency response characteristic has the passband, transition band and stop band of the first frequency response characteristic.