HDR Image Encoding with LDR Mismatch Detection
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Solution Overview
Problem
Existing JPEG-compressed images lack the ability to accurately represent high dynamic range (HDR) data, leading to quality degradation when edited, as HDR information and Low Dynamic Range (LDR) image mismatches are difficult to manage, especially during editing processes like resizing, rotation, or color changes, affecting the integrity and display quality of HDR images.
Innovation Solution
An image encoding apparatus that generates an LDR image and difference information from an HDR image, encodes the LDR image, calculates meta-data representing the LDR image's features, and stores the encoded LDR image and meta-data in a file structure, allowing for detection of mismatches between HDR and LDR information, ensuring proper handling of edited images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If HDR image data is stored using conventional JPEG compression format, then compatibility with existing JPEG viewers is maintained, but the ability to accurately represent high dynamic range information is lost
Solution Approach 1:
The patent divides the HDR image data into two separate components: LDR image data (for compatibility) and HDR information (for accuracy). These are stored together in a single JPEG file, allowing viewers to access either format as needed. The HDR information is embedded as additional data alongside the conventional LDR JPEG data.
Solution Approach 2:
The HDR information is nested within the JPEG file structure as additional data embedded alongside the conventional LDR image data. This allows the HDR information to be contained within the same file as the compatible JPEG data, enabling both formats to coexist without requiring separate files.
2Loss of information
If HDR information is stored in APP markers, then HDR data can be included with JPEG images, but the data becomes unrecognizable to viewers incapable of parsing APP markers
Solution Approach 1:
The patent segments the data into recognizable LDR JPEG data (for viewer compatibility) and APP marker data (for HDR information preservation). Viewers can process the LDR data while HDR-capable viewers can additionally parse the APP markers to access the full HDR information.
Solution Approach 2:
The LDR image data acts as an intermediary that all viewers can process, while the APP marker data serves as an additional layer for HDR-capable viewers. This intermediary structure allows gradual information disclosure based on viewer capability without forcing compatibility issues.
3Adaptability or versatility
If LDR image is edited after HDR information is embedded, then editing flexibility is improved, but mismatch between LDR image and HDR information occurs
Solution Approach 1:
The patent performs preliminary action by embedding HDR information before any LDR editing occurs. The HDR information is captured at the original image state, and any subsequent editing of the LDR image is recorded as metadata. This ensures the HDR information remains accurate relative to the original, unedited state.
Solution Approach 2:
The patent implements feedback mechanisms through metadata that tracks editing operations performed on the LDR image. This feedback information allows the system to understand what edits were made and adjust the HDR information accordingly, or at least document the mismatch between the edited LDR and original HDR data.
Data Source
AI summary
This invention makes it possible to detect only a relatively large mismatch while allowing a mismatch to some extent between an LDR image and HDR information, which are stored in a single file, caused by editing of the LDR image. An apparatus of this invention generates, from an input HDR image, an LDR image and difference information representing a difference between the LDR image and the HDR image. The generated LDR image is encoded. Information formed from data representing a local feature of the LDR image is calculated as LDR meta-data. The apparatus generates a file by storing the encoded data in a main encoded data storage region and storing the difference information and the LDR meta-data in a marker defined as a non-reference region for an LDR image decoding apparatus in the file structure.