Apple patents video codec that adjusts brightness range per frame
Apple describes a video encoding system that dynamically selects a specific brightness mapping for each frame of a video. This allows the codec to compress the video using fewer bits internally while still preserving the full range of light and dark details when the video is played back on a screen.
In the filing’s own words
A video encoding and decoding system that implements an adaptive transfer function method internally within the codec for signal representation. A focus dynamic range representing an effective dynamic range of the human visual system may be dynamically determined for each scene, sequence, frame, or region of input video. The video data may be cropped and quantized into the bit depth of the codec according to a transfer function for encoding within the codec. The transfer function may be the same as the transfer function of the input video data or may be a transfer function internal to the codec. The encoded video data may be decoded and expanded into the dynamic range of display(s). The adaptive transfer function method enables the codec to use fewer bits for the internal representation of the signal while still representing the entire dynamic range of the signal in output.
What exactly they claim (claim 1)
1. A system, comprising: a video encoder, configured to perform operations comprising: accessing a plurality of frames of source video data and a plurality of transfer functions used to map a full dynamic range of the source video data to a focus range of luminance values of the source video data; for each frame of the plurality of frames: selecting a particular transfer function of the plurality of transfer functions, and determining particular luminance values of the frame using the focus range of luminance values and the particular transfer function, wherein different transfer functions of the plurality of transfer functions are used corresponding to the plurality of frames; encoding a plurality of particular luminance values determined for the plurality of frames into encoded video data; generating format metadata providing information on the focus range luminance values and the plurality of transfer functions; and generating a bit stream comprising the encoded video data and the format metadata.
Facts
- Company
- Apple (Apple Inc.)
- Official title
- Adaptive transfer function for video encoding and decoding
- Patent number
- US12739397B2
- Application number
- 19025968
- Filed
- Jan 16, 2025
- Granted
- Sep 15, 2026
- Inventors
- 2
- Claims
- 20
Classified under
H04N 19/14 Electricity & electronicsG06F 3/1454 Physics & computingG06T 5/92 Physics & computingG09G 3/2007 Physics & computingG09G 5/005 Physics & computingG09G 5/02 Physics & computingMore from Apple in Cameras & imaging
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Summaries are simplified from the filing’s own abstract and first claim. A patent filing is not a product announcement.
Patent data and drawings: U.S. Patent and Trademark Office (USPTO). Nebula is not affiliated with or endorsed by the USPTO.