Ambient Headroom Adaptation Tone Mapping

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Solution Overview

Problem

Conventional display devices struggle to accurately represent high dynamic range and large color space content due to environmental and device-specific factors, leading to loss of color range and contrast, especially under non-ideal viewing conditions.

Innovation Solution

A processor adjusts the tone mapping curve for high dynamic range content based on ambient light conditions and display device characteristics using optical sensors, determining an anchor point and modifying the curve to maintain consistent perception across varying environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If tone mapping is performed using standard methods assuming ideal viewing conditions, then the content can be displayed on standard dynamic range devices, but the color range and contrast are lost due to ambient light and non-ideal viewing conditions

Engineering Contradiction:

Improveadaptability to different viewing environmentsVSAvoidloss of color range and contrast

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The system performs preliminary measurements of ambient lighting conditions and display characteristics before tone mapping. Optical sensors capture ambient light data and the system characterizes the display device properties in advance, allowing the tone mapping curve to be pre-adjusted to compensate for expected losses in color range and contrast under specific viewing conditions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically changes the tone mapping curve parameters based on measured ambient light conditions and display characteristics. By adjusting the curve shape, anchor points, and mapping transformations in response to varying environmental parameters, the system preserves color range and contrast across different viewing environments while maintaining compatibility with standard dynamic range displays

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If the display brightness is increased to compensate for ambient light, then visibility improves, but the contrast and color saturation are reduced due to additive light effects

Engineering Contradiction:

Improvedisplay brightnessVSAvoidloss of contrast and color saturation

Core Design Contradiction:

Illumination intensityVSLoss of information

Solution Approach 1:

The system adjusts multiple parameters of the tone mapping curve simultaneously - not just brightness but also the curve shape, anchor point positions, and color space transformations. This coordinated parameter adjustment allows the display to maintain contrast and color saturation even when brightness must be increased to overcome ambient light conditions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system measures and characterizes the ambient light conditions and display flaws (such as backlight leakage and reflection) to create compensatory tone mapping adjustments. By converting the harmful additive light effects into quantifiable parameters, the system applies counteracting transformations that preserve color fidelity and contrast despite the presence of ambient light

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If software corrections and tone mapping are applied to compensate for display flaws, then display accuracy improves, but the complexity of the processing increases

Engineering Contradiction:

Improvedisplay accuracyVSAvoidprocessing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs display characterization and ambient light measurement in advance, storing the results for reuse. By pre-capturing display device properties and environmental conditions, the system avoids repeated complex measurements and calculations during actual tone mapping operations, reducing real-time processing complexity while maintaining accuracy

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system introduces an intermediate tone mapping curve that serves as a bridge between the original high dynamic range content and the final displayed image. This intermediate representation encapsulates the complex transformations needed to compensate for display flaws and ambient conditions, simplifying the overall processing pipeline while maintaining display accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11473971B2Ambient headroom adaptation

Publication Date: 2022.10.18 APPLE INC

AI summary

A device comprises memory, a display characterized by a display characteristic, and processors coupled to the memory. The processors execute instructions causing the processors to receive data indicative of the display characteristic, data indicative of ambient lighting, and data indicative of content characteristics for a content item; determine a tone mapping curve for the content item based on the data indicative of content characteristics; determine a first, so-called “anchor” point along the tone mapping curve; modify a first portion of the tone mapping curve below the anchor point based on the data indicative of ambient lighting; modify a second portion of the tone mapping curve above the anchor point based on the data indicative of the display characteristic; perform tone mapping for the content item based on the modified toned mapping curve to obtain a tone mapped content item; and cause the display to display the tone mapped content item.