Image analysis – Color image processing – Color correction
Reexamination Certificate
2001-03-15
2004-09-07
Johns, Andrew W. (Department: 2621)
Image analysis
Color image processing
Color correction
C358S516000
Reexamination Certificate
active
06788813
ABSTRACT:
BACKGROUND SECTION
1. Field of the Invention
This invention relates generally to techniques for manipulating data, and relates more particularly to a system and method for effectively performing a white balance operation in the field of digital imaging.
2. Description of the Background Art
Implementing effective methods for manipulating data is a significant consideration for designers and manufacturers of contemporary electronic devices. However, effectively manipulating data with electronic devices may create substantial challenges for system designers. For example, enhanced demands for increased device functionality and performance may require more system processing power and require additional hardware resources. An increase in processing or hardware requirements may also result in a corresponding detrimental economic impact due to increased production costs and operational inefficiencies.
Furthermore, enhanced device capability to perform various advanced operations may provide additional benefits to a system user, but may also place increased demands on the control and management of various device components. For example, an enhanced electronic device that effectively captures and manipulates digital image data may benefit from an effective implementation because of the large amount and complexity of the digital data involved.
In certain electronic cameras that capture digital image data, a white balancing operation may be required. In practice, the human visual system does not perceive the same amount of light and the same colors that an electronic camera captures as image data. White balancing operations therefore adjust the image data captured by the electronic camera, so that a resultant captured image appears the same as the image that was originally perceived by the human eye.
Due to growing demands on system resources and substantially increasing data magnitudes, it is apparent that developing new techniques for manipulating data is a matter of concern for related electronic technologies. Therefore, for all the foregoing reasons, developing effective systems for manipulating data remains a significant consideration for designers, manufacturers, and users of contemporary electronic devices.
SUMMARY
In accordance with the present invention, a system and method are disclosed for effectively performing a white balance operation. In one embodiment, initially, a camera device may preferably set amplifier gains of red, green, and blue channel amplifiers to unity gain. Then, the camera device may preferably capture image data using a set of image sensors in a capture subsystem for one specific type of illumination that closely approximates equal energy illumination for the chosen set of image sensors.
Next, a segmentation subroutine of a color manager may preferably search for selected neutral areas in the captured image data according to pre-determined criteria, and the color manager may preferably determine whether qualified neutral areas exist in the image data. If the color manager identifies one or more neutral areas in the image data, then the color manager may preferably analyze the individual neutral areas to thereby determine relevant information such as a total pixel count for each neutral area and one or more representative color values for each neutral area.
In certain embodiments, the foregoing color values may preferably include a ratio of the red and green pixel values (a R/G value), and a ratio of the blue and green pixel values (a B/G value) that represent corresponding chromaticity components. However, it should be noted that R/G and B/G are just one example of how chromaticity may be measured, and other methods of representing chromaticity are equally within the scope of the present invention.
Next, the color manager may preferably determine a composite color value that represents combined color information for the neutral areas of the image data. The color manager may then preferably determine one or more appropriate color correction factors based upon the foregoing composite color values, to thereby adjust white-balance parameters of the camera device. Finally, the camera device may preferably apply the foregoing color correction factors to appropriate camera functionality (such as adjusting the amplifier gains of the red, green, and blue channel amplifiers) to thereby compensate for color cast artifacts in the image data.
In certain embodiments, electronic cameras of different primary colors (for example, cyan, yellow, and magenta) are also contemplated for utilization with the present invention. In addition, image sensors of more than three channels are likewise contemplated for utilization with the present invention. For example, electronic cameras that function with red, green, blue, and teal channels may be available in the near future.
In the event that the color manager fails to locate any neutral areas in the image data, the color manager may then preferably search for one or more potential memory color areas in the image data by utilizing any appropriate and effective techniques. For example, the color manager may identify regions in the image data that are above a certain memory color size threshold. If no potential memory color area is located in the image data, then the color manager may preferably utilize appropriate selectable system defaults to provide color correction factors for performing a white-balancing procedure for the camera device. For example, the color manager may utilize manufacturer default settings or may utilize values from one or more preceding white-balancing procedures in the camera device.
If a potential memory color area is located in the image data, then the color manager may preferably analyze the memory color area to obtain various types of relevant information. For example, the color manager may determine one or more memory color values for the potential memory color area. In certain embodiments, the foregoing memory color values may preferably include a R/G value and a B/G value.
The color manager may then preferably compare the foregoing memory color values to a color table with known color values for various memory colors under various illuminants. The color manager may preferably determine whether the foregoing memory color values of the potential memory color area are within a pre-determined range of a known color value for a particular memory color under a particular illuminant.
If the memory color values of the potential memory color area are within a pre-determined range of a known color value, then the color manager may preferably utilize various types of validity criteria to verify that the potential memory color area is a valid choice. The foregoing validity criteria may include any effective means for evaluating a potential memory color area. For example, the color manager may perform various memory color location tests, such as ensuring that a potential sky memory color area is near the top of the corresponding image. In addition, the color manager may also perform various illuminant tests, such as ensuring that a potential outdoor memory color is not matched with an indoor illuminant such as fluorescent lighting. The color manager may thus make a final identification of a memory color area in the image data only after a potential memory color area passes all validity testing procedures.
The color manager may then advantageously determine one or more correction factors based upon the identified memory color area by utilizing any appropriate and effective means. In certain embodiments, the color manager may preferably associate the identified memory color area with a closest matching known memory color from the foregoing color tables. In accordance with the present invention, the color manager may then reference the color tables to determine one or more known color values for the closest matching known memory color.
The color manager may then substitute the foregoing known color values for the closest matching known memory color to calculate the one or more correction values, instead of utilizing th
Alavi Amir
Johns Andrew W.
Koerner Gregory J.
Simon & Koerner LLP
Sony Corporation
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