Systems and methods for local tone mapping of high dynamic range images
First Claim
1. A method comprising:
- calculating an illumination component of an image input signal of high dynamic range by processing the input signal with a shape adaptive filter;
processing the calculated illumination component to generate a processed illumination component in which a contrast of the input signal has been compressed;
processing the calculated illumination component to generate a processed reflectance component in which at least one feature of the input signal has been sharpened;
generating a processed input signal from the processed illumination component and the processed reflectance component, wherein the processed input signal comprises a contrast-compressed and image-sharpened version of the input signal; and
mapping the processed input signal into a dynamic range of a display device,wherein calculating the illumination component further comprises;
calculating the input signal'"'"'s associated luminance signal by transforming a RGB input signal into a YCgCo color space; and
processing the luminance signal with the shape adaptive filter to calculate the illumination component,and wherein the shape adaptive filter calculates the illumination component through the equation;
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Abstract
This is generally directed to systems and methods for local tone mapping of high dynamic range (“HDR”) images. For example, a HDR image can have its larger dynamic range mapped into the smaller dynamic range of a display device. In some embodiments, to perform the local tone mapping, a RGB to Y converter can be used to convert the input image signal to a luminance signal in the YCgCo color space, a shape adaptive filter can be used to separate the luminance signal into its illumination and reflectance components, contrast compression can be applied to the illumination component, image sharpening can be applied to the reflectance component, and the processed illumination and reflection components can be used to calculate a processed RGB signal. The dynamic range of the processed RGB signal can then be mapped into the dynamic range of the display device.
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Citations
16 Claims
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1. A method comprising:
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calculating an illumination component of an image input signal of high dynamic range by processing the input signal with a shape adaptive filter; processing the calculated illumination component to generate a processed illumination component in which a contrast of the input signal has been compressed; processing the calculated illumination component to generate a processed reflectance component in which at least one feature of the input signal has been sharpened; generating a processed input signal from the processed illumination component and the processed reflectance component, wherein the processed input signal comprises a contrast-compressed and image-sharpened version of the input signal; and mapping the processed input signal into a dynamic range of a display device, wherein calculating the illumination component further comprises; calculating the input signal'"'"'s associated luminance signal by transforming a RGB input signal into a YCgCo color space; and processing the luminance signal with the shape adaptive filter to calculate the illumination component, and wherein the shape adaptive filter calculates the illumination component through the equation; - View Dependent Claims (2, 3, 4)
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5. A system comprising:
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a decomposer operable to receive a high dynamic range (“
HDR”
) image signal and decompose the image signal into at least an illumination component and a reflectance component;a contrast compressor operable to receive the illumination component and compress the contrast of the image signal by processing the illumination component; an image sharpener operable to receive the reflectance component and sharpen an image of the image signal by processing the reflectance component; a multiplier operable to multiply the processed illumination component by the processed reflectance component to calculate a processed luminance signal; a RGB processor operable to transform the processed luminance signal into its associated red, green, and blue signals; and a range mapper operable to map a dynamic range of the associated red, green, and blue signals into a dynamic range of a display device, wherein the decomposer; calculates the illumination component through the equation; - View Dependent Claims (6, 7, 8, 9, 10)
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11. A system for performing local tone mapping of an input image, comprising:
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a contrast compressor operable to receive and process an illumination component signal of the input image by; executing a power function on the illumination component signal to generate an Lp signal; and mapping a dynamic range of the Lp Signal into a dynamic range of the input image to generate a contrast-compressed signal; an image sharpener operable to receive and process a reflectance component signal of the input image by; executing a log function on the reflectance component signal to generate a Log(F) signal; executing a noise coring function on the Log(F) signal to reduce magnification of noise, thereby generating a noise-cored signal; and processing the received reflectance component signal and the noise-cored signal to generate a image-sharpened signal; and a range mapper operable to; generate a processed image signal from the contrast-compressed signal and the image-sharpened signal; and map the dynamic range of the processed image signal into a dynamic range of a display device, wherein the contrast compressor is further operable to; execute a power function on the illumination component defined by; - View Dependent Claims (12, 13, 14, 15, 16)
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Specification