In a system for coding high dynamic range (HDR) images using lower-dynamic range (LDR) images, a reshaping function allows for a more efficient distribution of the codewords in the lower dynamic range images for improved compression. A trim pass of the LDR images by a colorist may satisfy a director's intent for a given “look,” but may also result in unpleasant clipping artifacts in the reconstructed HDR images. Given an original forward reshaping function which maps HDR luminance values to LDR pixel values, a processor identifies areas of potential clipping and generates modified forward and backward reshaping functions to reduce the visibility of potential artifacts from the trim pass process while preserving the director's intent.

A method of adaptive chroma downsampling is presented. The method comprises converting a source image to a converted image in an output color format, applying a plurality of downsample filters to the converted image and estimating a distortion for each filter chose the filter that produces the minimum distortion. The distortion estimation includes applying an upsample filter, and a pixel is output based on the chosen filter. Methods for closed loop conversions are also presented.

A method of adaptive chroma downsampling is presented. The method comprises converting a source image to a converted image in an output color format, applying a plurality of downsample filters to the converted image and estimating a distortion for each filter chose the filter that produces the minimum distortion. The distortion estimation includes applying an upsample filter, and a pixel is output based on the chosen filter. Methods for closed loop conversions are also presented.

An information processing apparatus includes an interpolation target color difference pixel generator that generates, on the basis of a relationship between a luminance pixel at an interpolation target pixel position that is a pixel position at which a first color difference pixel does not exist and the luminance pixel at at least one neighboring pixel position of a plurality of pixel positions near the interpolation target pixel position in image data, an interpolation target color difference pixel corresponding to the first color difference pixel at the interpolation target pixel position, in which the image data is generated on the basis of three primary color pixels that can include a value greater than a predetermined white clip value, the image data having a number of the luminance pixels larger than a number of the first color difference pixels and a number of second color difference pixels.

A system is provided for converting image data from a first image format to a second image format that approximates a three-dimensional lookup table. The system includes an image processing operation database that stores image format conversion configurations; an image format conversion selector that selects an image format conversion for converting the image data from a first to a second format and that accesses, from the database, a corresponding image format conversion configuration for converting the image data to the second format; and an image processor that executes processing input operations on RGB components of the image data, a 3×3 matrix, and processing output operations on the respective RGB components that are output from the 3×3 matrix, such that the image data is converted to the second format, with the processing input and output operations comprising the accessed image format conversion configuration.

A conversion method for converting luminance of a video, including a luminance value in a first luminance range, to be displayed on a display apparatus includes: acquiring a first luminance signal indicating a code value obtained by quantization of the luminance value of the video; and converting the code value indicated by the acquired first luminance signal into a second luminance value determined based on a luminance range of the display apparatus, the second luminance value being compatible with a second luminance range with a maximum value smaller than a maximum value of the first luminance range and larger than 100 nit. This provides the conversion method capable of achieving further improvement.

A conversion method for converting luminance of a video, including a luminance value in a first luminance range, to be displayed on a display apparatus includes: acquiring a first luminance signal indicating a code value obtained by quantization of the luminance value of the video; and converting the code value indicated by the acquired first luminance signal into a second luminance value determined based on a luminance range of the display apparatus, the second luminance value being compatible with a second luminance range with a maximum value smaller than a maximum value of the first luminance range and larger than 100 nit. This provides the conversion method capable of achieving further improvement.

A method includes encoding a first message including first parameters for a first color transform that transforms a video signal into a first color-mapped video signal; encoding a second message including second parameters for a second color transform that transforms the video signal into a second color-mapped video signal; and encoding the video signal, the first message, and the second message in a video bitstream. A method includes decoding the video bitstream into the video signal, the first message including the first parameters, and the second message including the second parameters, and performing at least one of the following: displaying the video signal; transforming the video signal into the first color-mapped video signal by applying the first color transform and displaying the first color-mapped video signal; and transforming the video signal into the second color-mapped video signal by applying the second color transform and displaying the second color-mapped video signal.

A method includes encoding a first message including first parameters for a first color transform that transforms a video signal into a first color-mapped video signal; encoding a second message including second parameters for a second color transform that transforms the video signal into a second color-mapped video signal; and encoding the video signal, the first message, and the second message in a video bitstream. A method includes decoding the video bitstream into the video signal, the first message including the first parameters, and the second message including the second parameters, and performing at least one of the following: displaying the video signal; transforming the video signal into the first color-mapped video signal by applying the first color transform and displaying the first color-mapped video signal; and transforming the video signal into the second color-mapped video signal by applying the second color transform and displaying the second color-mapped video signal.

A method of determining luma values from 4:4:4 RGB video data for encoding chroma downsampled 4:2:0 YCbCr video data into a bitstream. Initial coefficents are determined for a region of a colour space the region being one of a plurality of regions located in the colour space and each region having a plurality of associated coefficients. The determined initial coefficients are applied to an initial image to produce a test image, the test image being a chroma downsampled 4:2:0 YCbCr version of the initial image. A measure of quality is determined by comparing the initial image and the test image. The determined initial coefficients are modified to increase the determined measure of quality. Luma values are determined from 4:4:4 RGB video data for encoding chroma downsampled 4:2:0 YCbCr video data into a bitstream using the modified coefficients.