HDR Image Luminance Correction via Dynamic Peak Luminance Adjustment
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Solution Overview
Problem
Existing technologies lack an effective method for luminance correction in HDR images, particularly when the output dynamic range changes, leading to deficiencies or excesses in correction amounts due to differences in peak luminance, affecting color reproduction and tone properties.
Innovation Solution
An image processing apparatus and method that generates correction information based on the difference between input/output characteristics with varying maximum output luminance values, allowing for luminance value correction in HDR images by applying a composite lookup table (LUT) that adjusts correction amounts according to the peak luminance, ensuring appropriate correction effects across different shooting modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the same color/luminance correction is applied to HDR images with different peak luminances, then the correction process is simple, but the correction effect becomes inaccurate due to tone property differences
Solution Approach 1:
The correction amount is made dynamic by adjusting it according to the peak luminance of the input/output characteristic. The system determines the peak luminance and selects or adjusts correction amounts accordingly, rather than applying a fixed correction. This dynamic adjustment resolves the contradiction by making the correction process adaptive to different shooting modes while maintaining accuracy.
Solution Approach 2:
The invention changes the correction parameter (correction amount) based on the peak luminance parameter. By establishing a relationship between peak luminance and correction amount, the system automatically adjusts correction parameters to match the shooting mode, thereby maintaining correction accuracy across different scenarios without complicating the overall process.
2Measurement precision
If correction amounts are adjusted according to peak luminance differences, then correction accuracy improves, but processing complexity increases
Solution Approach 1:
The system performs preliminary determination of the peak luminance and pre-establishes the relationship between peak luminance and correction amounts. By preparing correction information in advance based on the determined peak luminance, the system avoids complex real-time calculations during correction, thus improving accuracy while controlling processing complexity.
Solution Approach 2:
The invention introduces an intermediary element (correction information or lookup table) that mediates between the peak luminance and the final correction application. This intermediary stores pre-calculated correction amounts, simplifying the processing by avoiding direct complex calculations during the correction phase while maintaining high accuracy.
3Device complexity
If a fixed correction table is used for all shooting modes, then device complexity is reduced, but correction effectiveness deteriorates in high-luminance ranges
Solution Approach 1:
Instead of a completely fixed correction table, the system dynamically selects or adjusts correction amounts based on the peak luminance. This dynamic approach maintains reliability in high-luminance ranges by adapting correction amounts to the shooting mode, while keeping the system relatively simple through the use of pre-established correction information.
Solution Approach 2:
The invention applies local quality by using different correction amounts for different luminance ranges and shooting modes. Rather than a uniform correction approach, the system tailors correction characteristics to specific conditions (high peak luminance vs. low peak luminance), ensuring effectiveness in high-luminance ranges while maintaining overall system simplicity through structured correction information.
Data Source
AI summary
There is provided an image processing apparatus. An obtaining unit obtains a first image to which tone conversion processing conforming to a first input/output characteristic having a first maximum output luminance value has been applied. A generation unit generates first correction information for correcting a luminance value of the first image based on a difference regarding an output luminance value between the first input/output characteristic and a second input/output characteristic having a second maximum output luminance value, and on second correction information for correcting a luminance value of a second image to which tone conversion processing conforming to the second input/output characteristic has been applied. A correction unit corrects a luminance value of the first image in conformity to the first correction information.