Computer graphics processing and selective visual display system – Display peripheral interface input device
Reexamination Certificate
2000-07-10
2001-03-13
Cuchlinski, Jr., William A. (Department: 3661)
Computer graphics processing and selective visual display system
Display peripheral interface input device
C345S440000, C345S442000
Reexamination Certificate
active
06201531
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to image editing systems, and more particularly, to a method and apparatus for changing a color of an image.
BACKGROUND OF THE INVENTION
Producers of still pictures and motion video programs use a variety of special effects to produce a final product. A graphics editor performs the task of adding special effects to still pictures and to motion video segments using a graphics workstation.
Color changing is a special effect that involves changing the color of certain pixels within one or more video image frames. One application of color changing involves modifying the color of an object to make it more or less noticeable in the video image frame. Another application of color changing is to repair a damaged portion of the video image frame. A third application of color changing is to add color to a video image frame to generate the appearance of one or more new objects in the video image frame.
To achieve a color change effect, the graphics editor, using a mouse, graphics tablet or similar input device, manually circumscribes an area of a video image frame that is to receive the color change effect using the graphics workstation. Then, the graphics editor changes the color of each pixel within the circumscribed area to a specified destination color.
Since every pixel within the circumscribed area is changed to the new destination color, the graphics editor must circumscribe the intended color change area with precision. If the graphics editor does a poor job of circumscribing the area, some pixels that were not intended to be changed may be changed, and some pixels intended to be changed may be left unchanged.
Generally, the graphics editor's ability to circumscribe an object in a video image frame is limited. One way for the graphics editor to circumscribe the object is by controlling a cursor on the graphics workstation by manually moving a mouse. In particular, the graphics editor attempts to exactly trace the border around the object with the cursor. Such work requires good hand-eye coordination and is typically painstaking.
Producing color change effects using the above-described technique has additional drawbacks. In particular, setting each pixel of an object to be a destination color generally makes the object look flat and two-dimensional rather than three-dimensional which is often preferred. Additionally, it is not practical for a graphics editor to perform this process on frames of motion video footage that may include a sequence of hundreds or even thousands of individual frames. Furthermore, conventional color correction algorithms performed on computers are complex and require substantial computer power.
SUMMARY OF THE INVENTION
The present invention overcomes these drawbacks by approximately identifying an object in an image, and changing an original color of the object only when the object is covered by an alpha matte, and when a distance between the original color and a target color is below a predetermined threshold.
Accordingly, an aspect of the invention is a computer-implemented process for changing a color of an image. In this process, a source frame that includes the image is received. An alpha matte that covers an object in the source frame is created. An original color of a pixel in the source frame is changed when the pixel is covered by the alpha matte, and when a color distance between the original color of the pixel and a target color is below a predetermined threshold.
REFERENCES:
patent: 5488674 (1996-01-01), Burt et al.
patent: 5557339 (1996-09-01), Dadourian
patent: 6128001 (2000-10-01), Gonsalves et al.
Chou Chia-Sheng
Cooper Brian C.
Gonsalves Robert
Scoppettuolo Dion C.
Avid Technology Inc.
Cuchlinski Jr. William A.
Marc-Coleman Marthe Y.
Milik Kenneth L.
Monks Lawrence E.
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