Techniques for selective enhancement of a digital image
AssigneeEastman Kodak Company
InventorDavid C. Wilkins
Life of this patent
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Abstract
By automatically compensating for unwanted lighting effects caused by varying ambient light sources, digital still images and video are made to appear more naturally realistic. A set of correction factors based upon an ascertained ambient lighting conditions, such as color temperature, provides for selectively color correcting only those pixels requiring correction. In this way, only those portions of a digital image having excessive color due to ambient light conditions are improved without affecting those portions of the digital image not requiring correction.
Claims13
A method of automatically color correcting a digital image taken under an ambient light source, comprising:
- (a) converting the digital image to a selected color space, wherein each of the pixels has an associated set of color space components;
- b) determining a characteristic color temperature of the ambient light source;
- (c) selecting a first color component and a second color component of the set of color space components having a first color component value and a second color component value, respectively;
- (d) determining the number of pixels of the digital image having both their respective first color component value within a predetermined range of first color component values and their second color component values within a predetermined range of second color component values, wherein the range of first color component values and the range of second color component values are based upon the characteristic ambient color temperature;
- and
- (e) if the number of pixels from (d) is greater than a pixel threshold value, then for each pixel in the digital image having its respective first color component value within the predetermined range and its second color component value within the predetermined range of second color component values, modifying that pixel's set of color components.
An apparatus for enhancing a digital image made up of pixels by removing a particular color, comprising:
- a first means for converting the digital image to a selected color space, wherein each of the pixels has an associated set of color space components;
- a second means coupled to the first means for determining a characteristic color temperature of the ambient light source;
- a third means coupled to the second means for selecting a first color component and a second color component of the set of color space components having a first color component value and a second color component value, respectively;
- a fourth means coupled to the third means for determining the number of pixels of the digital image having both their respective first color component value within a predetermined range of first color component values and their second color component values within a predetermined range of second color component values, wherein the range of first color component values and the range of second color component values are based upon the characteristic ambient color temperature;
- and
- a fifth means for modifying that pixel's set of color components when the number of pixels from determined by the fourth means is greater than a pixel threshold value, then for each pixel in the digital image having its respective first color component value within the predetermined range and its second color component value within the predetermined range of second color component values.
Dependencies are inferred from the claim text.