Method of performing adaptive contrast enhancement using hyperbolic tangent curve and image histogram
AssigneeLG Innotek Co., Ltd.
InventorsSoo Jin Park, Deepak Chandra Bijalwan, Naveen Koul
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Abstract
Disclosed is a method of performing contrast enhancement for an image. A mean luminance value is calculated with respect to an image that is read, the type of the image is determined based on the mean luminance value, a contrast reference curve is created by using a hyperbolic tangential function curve according to the type of the image, and the contrast of the image is enhanced by using the contrast reference curve.
Claims4
A method of performing adaptive contrast enhancement according to image types, the method comprising:
- reading an image;
- calculating a mean luminance value and luminance histogram of the image;
- determining a type of the image based on the mean luminance value and the luminance histogram;
- creating contrast reference curves by applying different coefficients according to image types to a hyperbolic tangential function curve;
- and
- performing contrast enhancement of the image by using the contrast reference curves;
- wherein the type of the image is determined as a low lighting image in a case of 0<the mean luminance value≦50, a regular lighting image in a case of 50<the mean luminance value≦200, a back lighting image in a case of 200<the mean luminance value≦255, and a high contrast image in a case in which a maximum number of pixel counts is represented at both high and low luminance values in luminance histogram distribution.
A method of performing adaptive contrast enhancement according to image types, the method comprising:
- reading an image;
- calculating a mean luminance value and luminance histogram of the image;
- determining a type of the image based on the mean luminance value and the luminance histogram;
- creating contrast reference curves by applying different coefficients according to image types to a hyperbolic tangential function curve;
- and
- performing contrast enhancement of the image by using the contrast reference curves,
- wherein the performing of contrast enhancement includes:
- reading RGB values of the image;
- converting the RGB values into HSV space values;
- mapping a V value of the HSV space values by using the contrast reference curves;
- combining a mapped V value with HS values;
- and
- converting the combined HSV values into RGB values.
Dependencies are inferred from the claim text.