Method for enhancing the edge contrast of a digital image
First Claim
1. A method for utilizing a predetermined tone scale conversion to enhance a digital image comprised of a plurality of image pixels, each image pixel characterized by an image value, said method comprising the steps of:
- (a) providing image pixels corresponding to a region of the image;
(b) identifying a statistical characteristic of the image pixels in the region, wherein the statistical characteristic is a gradient value;
(c) normalizing the predetermined tone scale conversion for the statistical characteristic in order to generate a normalized tone scale conversion; and
(d) performing the normalized tone scale conversion on a central pixel of the region in order to generate an enhanced output pixel.
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Abstract
A method for utilizing a predetermined tone scale conversion to enhance a digital image comprised of a plurality of image pixels, each image pixel characterized by an image value, includes the steps of providing image pixels corresponding to a region of the image; identifying a statistical characteristic of the image pixels in the region; normalizing the predetermined tone scale conversion for the statistical characteristic in order to generate a normalized tone scale conversion; and performing the normalized tone scale conversion on a central pixel of the region in order to generate an enhanced output pixel. In one embodiment, a scaling function is generated based upon the statistical parameter and a first intermediate value is generated from application of the scaling function to the input pixel value. Then a second intermediate value is generated from the application of the first intermediate value to the tone scale function, and an enhanced pixel value is then obtained from application of the inverse of the scaling function to the second intermediate value.
45 Citations
26 Claims
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1. A method for utilizing a predetermined tone scale conversion to enhance a digital image comprised of a plurality of image pixels, each image pixel characterized by an image value, said method comprising the steps of:
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(a) providing image pixels corresponding to a region of the image;
(b) identifying a statistical characteristic of the image pixels in the region, wherein the statistical characteristic is a gradient value;
(c) normalizing the predetermined tone scale conversion for the statistical characteristic in order to generate a normalized tone scale conversion; and
(d) performing the normalized tone scale conversion on a central pixel of the region in order to generate an enhanced output pixel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for enhancing a digital image processed through a digital image channel, the method comprising the steps of:
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a) receiving a pixel value from a spatial region of the digital image;
b) receiving a tone scale function;
c) calculating a statistical parameter based on the values of other pixels in the spatial region of the digital image;
d) generating a scaling function based upon the statistical parameter;
e) generating a first intermediate value from the pixel value and the scaling function;
f) generating a second intermediate value from the first intermediate value and the tone scale function; and
g) generating an enhanced pixel value from an inverse of the scaling function, and the second intermediate value. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification