Method of processing high dynamic range images using dynamic metadata
A method of performing luminance/brightness adjustment and gamut mapping to high dynamic range images for a display device includes receiving an input image to analyze an image distribution of the input image, generating a scene information of the input image according to the image distribution, and performing luminance/brightness adjustment and gamut mapping to the input image according to the scene information, to generate an output image corresponding to the input image, wherein the scene information is regarded as dynamic metadata of the input image.
1. A method of performing gamut mapping to high dynamic range images for a display device, comprising:
receiving an input image to analyze a color distribution of the input image;
determining a protect range corresponding to a first percentage of color codes of the input image and a compression range corresponding to a second percentage of the color codes of the input image based on the color distribution of the input image; and
moving at least one of the color codes of the input image outside the protect range of the color codes to the compression range by a non-linear compression algorithm to perform gamut mapping to the input image.
2. The method of claim 1 , wherein the color distribution comprises a color distribution in red, green, blue channels, and a luminance distribution in a luminance channel.
3. The method of claim 1 , further comprising generating a scene information of the input image according to the color distribution, wherein the scene information comprises at least one of a mean, a maximum, a minimum, and a portion of pixel counts in red, green, blue, and luminance channels, and the scene information is regarded as dynamic metadata of the input image.
4. The method of claim 3 , further comprising:
calculating an input gamut range of the input image, a display gamut range of the display device, gamut nodes value, the protect range and the compression range according to the scene information, a display capability of the display device, and a user preference; and
performing gamut mapping according to the input gamut range, the display gamut range, the gamut nodes value, the protect range and the compression range to generate an output image corresponding to the input image.
5. The method of claim 4 , wherein a node of the input image whose color code is inside the protect range is completely preserved.
6. The method of claim 4 , wherein the gamut mapping is 3-dimensional color volume mapping in an LCH (Lightness, Chromaticity, Hue angle) color domain.