Movie enhancement
View Patent ↗A method for enhancing video or other multimedia in order to achieve a closer-to-movie theater viewing experience. The enhancement method can be applied to YUV or other video formats which are used for TV or digital media. The method provides a curve with at least one inflection point such that at least one region has a concave upward arc and another region has a concave downward arc. The improved curve provides relatively less contrast in relatively dark regions and relatively more contrast in relatively bright regions. By taking into account the visual sensitivity to various luminance levels, a neutral point is selected to be located at a relatively dark point. To the darker side of the neutral point, luminance is suppressed. To the brighter side of the neutral point, luminance is enhanced. This luminance-mapping curve is applied to the luminance (Y) signal so as to enhance both brightness and contrast.
1. A method for enhancing a video signal comprising:
obtaining intensity of luminance values and variation of chrominance values;
calculating average and variance of said luminance values and said chrominance values;
calculating a luminance-contrast adjustment based upon said luminance values;
constructing a luminance curve responsive to a luminance-mapping curve undulating about a point of inflection defined by a neutral point;
constructing a final enhancement mapping curve based on values of control factor intensity and said luminance values, wherein both ends of the final enhancement mapping curve may be re-interpolated to provide a soft-clipping effect;
constructing a chrominance curve based upon said chrominance values; and
applying the luminance curve, the final enhancement mapping curve, and the chrominance curve to the video signal.
2. The method for enhancing a video signal of claim 1 , whereby some or all of the operations are performed for every frame of the video signal.
3. The method for enhancing a video signal of claim 1 , whereby the intensity and variation are input by a user.
4. The method for enhancing a video signal of claim 1 , whereby the curves are realized as a fixed-point lookup table and mapping calculations are realized by table watching or third order of higher polynomials are used to emulate the curves.
5. The method for enhancing a video signal of claim 1 , further comprising:
obtaining an output luminance signal;
obtaining an output chrominance signal; and
restoring color saturation from chrominance adjustment.
6. A method for enhancing a video signal comprising:
obtaining user-input intensity of luminance values and variation of chrominance values;
calculating average of said luminance values, variance of said luminance values, and variance of said chrominance values;
calculating luminance-contrast adjustment from intensity of said luminance values, average of said luminance values, and variance of said luminance values;
constructing a luminance curve from a luminance-mapping curve, intensity of said luminance values, and luminance-contrast adjustment, the luminance-mapping curve undulating about a point of inflection defined by a neutral point;
constructing a final enhancement mapping curve based on values of control factor intensity and said luminance values, wherein both ends of the final enhancement mapping curve may be re-interpolated to provide a soft-clipping effect;
constructing a chrominance curve from variation of said chrominance values and variance of said chrominance values; and
applying the luminance curve, the final enhancement mapping curve. and the chrominance curve to the video signal.
7. The method for enhancing a video signal of claim 6 , whereby the curves are realized as a fixed-point lookup table and mapping calculations are realized by table watching.
8. The method for enhancing a video signal of claim 6 , whereby third order or higher polynomials are used to emulate the curves.
9. The method for enhancing a video signal of claim 6 , further comprising:
obtaining an output luminance signal;
obtaining an output chrominance signal; and
restoring color saturation from chrominance adjustment.
10. The method for enhancing a video signal of claim 9 , whereby the operations of obtaining the output luminance signal, obtaining the output chrominance signal, and restoring color saturation from chrominance adjustment are performed for every pixel.