Methods and apparatuses for restoring color and enhancing electronic images
View Patent ↗Methods and apparatuses for color image restoration and enhancement. In at least one embodiment, color signals for individual channels of an image (e.g., red, green, or blue) are adjusted based on a weighted set of averages (e.g., of the entire image, the center portion, the surrounding portion, or other portions). In one example, pixels with extreme values of color signals (e.g., pure black or white pixels) are ignored for the purposes of restoring color; and, the different averages are weighted according to the pixel location (e.g., the distance from the pixel to a center point). In one example, after color restoration for individual channels, the luminance of each pixel is adjusted back to their original levels; and the range of luminance of the image is further adjusted to provide improved brightness and contrast, where in determining the luminance the red, green and blue color channels are given an equal weight.
1. A computer readable medium encoded with a computer program instructions which when executed by a data processing system cause said system to perform a method to transform an electronic image, the method comprising:
determining one or more averages of a color channel for the image by excluding one or more first pixels of the image, each of the one or more first pixels being one of:
a) substantially white, and
b) substantially black; and
scaling color signals of the color channel for second pixels of the image according to the one or more averages, each of the second pixels being not one of:
a) substantially white, and
b) substantially black,
wherein the one or more averages comprise at least two of:
(a) an average for a center portion of the image,
(b) an average for a surrounding portion of the image, and
(c) an average for the image, and
wherein each of the color signals is scaled with respect to a signal of a selected color in the color channel by a factor which is a function of: the one or more averages and a distance to a selected point in the image.
2. A data processing system to transform an electronic image, the data processing system comprising:
means for determining one or more averages of a color channel for the image by excluding one or more first pixels of the image, each of the one or more first pixels being one of:
a) substantially white, and
b) substantially black; and
means for scaling color signals of the color channel for second pixels of the image according to the one or more averages, each of the second pixels being not one of:
a) substantially white, and
b) substantially black,
wherein the one or more averages comprise at least two of:
a) an average for a center portion of the image;
b) an average for a surrounding portion of the image, and
c) an average for the image, and
wherein each of the color signals is scaled with respect to a signal of a selected color in the color channel by a factor which is a function of the one or more averages and a distance to a selected point in the image.
3. An image capturing device, comprising:
an image sensing device to generate an electronic image; and
a processing circuit coupled to the image sensing device, the processing circuit being configured to determine one or more averages of a color channel for the image by excluding one or more first pixels of the image, each of the one or more first
pixels being one of:
a) substantially white, and
b) substantially black; and
the processing circuit being configured to scale color signals of the color channel for second pixels of the image according to the one or more averages, each of the second pixels being not one of:
a) substantially white, and
b) substantially black,
wherein the one or more averages comprise at least two of:
a) an average for a center portion of the image;
b) an average for a surrounding portion of the image; and
c) an average for the image;
wherein each of the color signals is scaled by the one or more averages to generate respectively one or more signals that are weighted according to a distance to a selected point in the image.
4. A computer readable medium encoded with computer program instructions which when executed by a data processing system cause said system to perform a method to transform an electronic image, the method comprising:
determining a plurality of averages of a color channel for the image; and
scaling color signals of the color channel for the image according to the plurality of averages;
wherein the plurality of averages comprise at least one of:
a) an average for a center portion of the image,
b) an average for a surrounding portion of the image,
c) an average for the image, and
wherein each of the color signals is scaled with respect to a signal of a selected color in the color channel by a factor which is a function of: the plurality of averages and a distance to a selected point in the image.