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US 2024/0196019 A1Published application
Extended bit-range in heif
AssigneeApple Inc.
InventorsLeo BARNES, Davide CONCION, Alexandros TOURAPIS
Life of this patent
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Abstract
Improved image coding techniques for high-bit depth images includes deriving two or more separate lower-bit-depth main and extension images from one high-bit-depth source image, and then encoding them separately as lower-bit-depth images. At a decoder, the separate main and extension images are decoded, and then combined to create a single reconstructed source image. The improved techniques may use lossless or lossy codecs, and may provide some backward compatibility with legacy decoders.
Claims20
An image encoding method, comprising:
- deriving a main image from most significant bits of pixel values of a source image, pixel values of the main image having a main bit depth determined by a selected upshift number;
- encoding the main image according to a coding protocol;
- decoding the encoded main image as a reconstructed main image;
- deriving an extension image from the reconstructed main image, the source image and the selected upshift number, wherein pixel values of the extension image have an extension bit depth;
- encoding the extension image according to the coding protocol;
- storing, according to a syntax of a coded media file, the encoded main image, the encoded extension image, and coding parameters indicating the extension bit depth and the selected upshift number.
3 more elements
An image decoding method, comprising:
- extracting, from a syntax in a coded media file, an encoded main image, an encoded extension image and coding parameters including a selected upshift number of bits and an extension bit depth;
- decoding the encoded main image according to a coding protocol to produce a reconstructed main image having pixels with a main bit depth;
- decoding the encoded extension image according to the coding protocol to produce a reconstructed extension image having pixel with the extension bit depth;
- combining the reconstructed main image with the reconstructed extension image based on the selected upshift number and the extension bit depth to produce a reconstructed source image.
1 more element
An image decoder, comprising:
- a parser configured for parsing, from syntax in a coded media file, an encoded main image, an encoded extension image, and coding parameters including a selected upshift number of bits and an extension bit depth;
- an image decoder for decoding an encoded image according to a coding protocol;
- an extension combiner for combing a main image with an extension image;
- and
- a controller configured to cause:
- decoding, by the image decoder, the encoded main image to produce a reconstructed main image having pixels with a main bit depth;
- decoding, by the image decoder, the encoded extension image to produce a reconstructed extension image having pixel with the extension bit depth;
- combining, by the extension combiner, the reconstructed main image with the reconstructed extension image based on the selected upshift number and the extension bit depth to produce a reconstructed source image.
5 more elements
Dependencies are inferred from the claim text.