Real-Time WDR Image Generator Using Luminance Extraction
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Solution Overview
Problem
Wide dynamic range (WDR) image generators, particularly of the TMO type, face challenges with slow calculation times and color distortion when processing high-resolution images, due to complex operations like natural log and exponential functions, which hinder real-time processing and synchronization with other blocks, and result in color distortion.
Innovation Solution
A real-time WDR image generator that extracts luminance components from RGB values, uses a log summation block to calculate a tone mapping lookup table, and applies a tone mapping operator to generate a final output, reducing logical operations through a 32-step log lookup table and orthogonal HSV domain processing, enabling real-time high-speed image processing without color distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If TMO type tone mapping is used to improve image quality, then performance is improved, but calculation time increases and real-time processing becomes difficult
Solution Approach 1:
The patent pre-calculates and stores tone mapping operators for different luminance ranges in lookup tables before actual image processing. During real-time processing, the system only needs to query these pre-computed tables rather than performing complex logarithmic calculations, thus maintaining high image quality while achieving real-time processing speeds.
Solution Approach 2:
The patent divides the luminance range into multiple segments (e.g., 32 ranges from 0-255) and creates separate tone mapping operators for each segment. This segmentation allows the system to handle different luminance levels with optimized pre-computed operators, reducing the computational burden during real-time processing while maintaining accurate tone mapping for each luminance range.
2Measurement precision
If natural log and exponential functions are performed for each pixel to achieve accurate tone mapping, then tone mapping precision is improved, but processing speed deteriorates
Solution Approach 1:
The system pre-computes tone mapping operators using logarithmic and exponential functions for each luminance range segment and stores them in lookup tables. During actual image processing, these pre-computed operators are directly applied without performing the complex mathematical functions again, thus maintaining precision while achieving real-time processing speeds.
Solution Approach 2:
The patent creates copies of tone mapping operators for different luminance ranges and stores them in lookup tables. Instead of recalculating the same mathematical operations for each pixel, the system copies and applies the appropriate pre-computed operator based on the pixel's luminance range, dramatically reducing processing time while maintaining accuracy.
3Speed
If color space transfer to RGB is performed for real-time processing, then processing speed is improved, but color distortion occurs
Solution Approach 1:
The patent extracts only the luminance component from the RGB color space while discarding the chrominance components. By working solely with luminance values for tone mapping operations, the system avoids the color distortion that arises from correlating color and luminance components, while maintaining processing speed through simplified operations.
Solution Approach 2:
The patent uses luminance as an intermediary between the input image and final output, performing all tone mapping operations in the luminance domain rather than directly manipulating RGB color values. This intermediary approach preserves color accuracy by decoupling luminance adjustments from color information, while still enabling real-time processing through efficient luminance-only calculations.
Data Source
AI summary
A real-time image generator is disclosed. A real-time image generator may include a first block extracting only a luminance component having a saturation, hue, and value domain from red, green and blue values of an image. A second block outputs a log summation value and pixel count value with respect to a luminance component of an overall image by using the extracted luminance component and a natural log value. A third block calculates a luminance average value of the image by using the natural log summation value and the pixel count value outputted in the second block, the third block generating a tone mapping look up table including a tone mapping operator (Ld) for each luminance range to obtain a final output image using the calculated luminance average value. The third block outputs a tone mapped red, green and blue value by multiplying a corresponding tone mapping operator (Ld) of the tone mapping look up table by a red, green and blue value of the input image.