Multi-Scale Local Contrast Enhancement for Display Dynamic Range
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Solution Overview
Problem
Digital displays are limited in their dynamic range, failing to replicate the full luminance range perceived by the human eye, leading to lost details in both bright and dark areas of images, as they cannot match the dynamic range capabilities of imaging devices.
Innovation Solution
The implementation of a multi-scale local contrast enhancement system within an image signal processing pipeline, which includes noise reduction, tone mapping, and color correction to enhance image contrast and maintain the original scene's contrast, bridging the gap between imaging and display technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If digital displays are used to reproduce images, then images can be displayed to users, but the limited dynamic range of displays causes loss of detail in bright and dark areas compared to the original scene
Solution Approach 1:
The image is divided into multiple local regions or tiles, and contrast enhancement is applied independently to each region. This segmentation allows different parts of the image with varying luminance characteristics to be processed differently, preserving details in both bright and dark areas without being constrained by the display's limited dynamic range.
Solution Approach 2:
The patent applies local contrast enhancement by computing contrast metrics and applying tone curves specific to each local region rather than uniformly across the entire image. This local quality approach ensures that each region's unique luminance characteristics are preserved, maintaining detail visibility in both highlights and shadows despite the display's limited dynamic range.
2Loss of information
If contrast enhancement is applied to compensate for display limitations, then detail visibility improves, but the original scene's contrast may be distorted
Solution Approach 1:
The system computes contrast metrics from the original image and uses this feedback to guide the tone mapping process. By continuously referencing the original scene's contrast characteristics and adjusting the enhancement parameters accordingly, the system preserves the original contrast relationships while compensating for display limitations.
Solution Approach 2:
The patent performs preliminary analysis of the original image to compute contrast metrics and determine appropriate tone curves before applying contrast enhancement. This preliminary action ensures that the enhancement process is guided by the original scene's characteristics, maintaining faithfulness to the source while improving detail visibility.
Data Source
AI summary
A circuitry-implemented method includes receiving an image pyramid of an image; convolving each level of the image pyramid with a kernel; constructing, based at least in part on the convolving of each level of the image pyramid, a base image pyramid; and generating a detail layer of the image by subtracting, from the image, a selected level of the base image pyramid from the image. Various other apparatuses, systems, and methods are also disclosed.