HDR Image Encoding via Tone Map Segmentation
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Solution Overview
Problem
Conventional digital image formats are unable to effectively store and reproduce high dynamic range (HDR) images, resulting in large file sizes and compatibility issues with legacy devices, which limits the ability to accurately represent real-world scenes with high contrast ratios.
Innovation Solution
A method and data structure that encodes high dynamic range image data by generating tone map data with a lower dynamic range, allowing for the storage of HDR information alongside tone map information in a format readable by both standard and HDR image viewers, using existing formats like JFIF and MPEG, ensuring backwards compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional digital image formats are used to store HDR images, then compatibility with legacy devices is maintained, but the dynamic range and image quality are insufficient
Solution Approach 1:
The patent segments the HDR image data into two separate components: tone map data (representing the image at lower dynamic range) and ratio data (representing the HDR information). This segmentation allows legacy devices to process only the tone map data while HDR-capable devices can combine both components to achieve full HDR image quality, thus resolving the contradiction between image quality and compatibility.
Solution Approach 2:
The tone map data serves as an intermediary that bridges HDR and standard dynamic range systems. It contains the essential visual information in a format compatible with legacy devices, while the ratio data acts as a supplemental intermediary that provides additional HDR information when needed, enabling gradual adoption without requiring complete system replacement.
2Reliability
If HDR image data is stored in full resolution, then image quality is preserved, but file size becomes prohibitively large
Solution Approach 1:
The patent extracts only the essential HDR information (ratio data) from the full HDR image, separating it from the tone map data. This extraction allows the HDR information to be stored in a compact form that references the tone map rather than duplicating the entire high-resolution HDR dataset, significantly reducing file size while preserving image quality.
Solution Approach 2:
Instead of storing complete HDR information at full resolution, the patent uses partial action by storing ratio data at reduced resolution or with reduced precision. This partial representation is sufficient for reconstructing HDR images when combined with tone map data, achieving acceptable image quality with significantly smaller file sizes.
3Reliability
If specialized software is used to view HDR images, then HDR image quality can be reproduced, but ease of operation and accessibility are reduced
Solution Approach 1:
The patent creates a universal data structure that can be interpreted by both legacy devices and HDR-capable devices. The tone map portion ensures universal compatibility with standard image viewers, while the ratio data portion provides enhanced functionality for HDR-capable viewers, thus achieving multi-functionality that maintains both accessibility and HDR reproduction accuracy.
Solution Approach 2:
The patent changes the parameter representation by storing HDR information as ratios rather than absolute values. This parameter transformation allows the same data structure to serve dual purposes: as complete HDR data for advanced viewers and as standard image data for legacy viewers, improving accessibility without sacrificing HDR capability.
Data Source
AI summary
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.