Encoding, decoding and representing high dynamic range images
First Claim
1. A method for encoding high dynamic range image data having an initial dynamic range, the method comprising:
- obtaining tone map data corresponding to the high dynamic range image data, the tone map data having a reduced dynamic range lower than the initial dynamic range;
processing the high dynamic range image data and the tone map data by a machine to yield ratio data, the ratio data comprising ratios of values in the high dynamic range image data and corresponding values in the tone map data;
generating high dynamic range information based on the ratio data;
generating tone map information based on the tone map data; and
,storing the high dynamic range information and the tone map information in a data structure;
wherein generating the high dynamic range information comprises applying to the ratio data a correction function, the correction function based on the tone map data;
the correction function is of the form;
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Abstract
A data structure defining a high dynamic range image comprises a tone map having a reduced dynamic range and HDR information. The high dynamic range image can be reconstructed from the tone map and the HDR information. The data structure can be backwards compatible with legacy hardware or software viewers. The data structure may comprise a JFIF file having the tone map encoded as a JPEG image with the HDR information in an application extension or comment field of the JFIF file, or a MPEG file having the tone map encoded as a MPEG image with the HDR information in a video or audio channel of the MPEG file. Apparatus and methods for encoding or decoding the data structure may apply pre- or post correction to compensate for lossy encoding of the high dynamic range information.
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Citations
36 Claims
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1. A method for encoding high dynamic range image data having an initial dynamic range, the method comprising:
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obtaining tone map data corresponding to the high dynamic range image data, the tone map data having a reduced dynamic range lower than the initial dynamic range; processing the high dynamic range image data and the tone map data by a machine to yield ratio data, the ratio data comprising ratios of values in the high dynamic range image data and corresponding values in the tone map data; generating high dynamic range information based on the ratio data; generating tone map information based on the tone map data; and
,storing the high dynamic range information and the tone map information in a data structure; wherein generating the high dynamic range information comprises applying to the ratio data a correction function, the correction function based on the tone map data; the correction function is of the form; - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 35, 36)
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29. A method for encoding high dynamic range image data having an initial dynamic range, the method comprising:
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obtaining tone map data corresponding to the high dynamic range image data, the tone map data having a reduced dynamic range lower than the initial dynamic range; processing the high dynamic range image data and the tone map data by a machine to yield ratio data, the ratio data comprising ratios of values in the high dynamic range image data and corresponding values in the tone map data; generating high dynamic range information based on the ratio data; generating tone map information based on the tone map data; and
,storing the high dynamic range information and the tone map information in a data structure; wherein; the tone map data is encoded by lossy encoding and the method comprises decoding the tone map data and subsequently computing the ratio data from the decoded tone map data; storing the tone map information comprises storing the encoded tone map data; generating the high dynamic range information comprises compressing the ratio data to yield compressed ratio data; generating the high dynamic range information comprises applying to the ratio data a correction function, the correction function based on the tone map data; the correction function is of the form;
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34. Apparatus for encoding high dynamic range image data having an initial dynamic range, the apparatus comprising:
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means for computing ratio data, the ratio data comprising ratios of values in the high dynamic range image data to corresponding values in tone map data corresponding to the high dynamic range image data, the tone map data having a reduced dynamic range lower than the initial dynamic range; means for generating high dynamic range information based on the ratio data; means for generating tone map information based on the tone map data; and
,means for storing the high dynamic range information and the tone map information in a data structure; wherein generating the high dynamic range information comprises applying to the ratio data a correction function, the correction function based on the tone map data; the correction function is of the form;
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Specification