为了提高在强光下显示屏的可读性，在不影响功耗和设备寿命等其他重要方面的情况下保持图像清晰度是一个重大的挑战。传统的技术方案往往有不足之处，在环境光亮度很高的情况下，图像变模糊，可视性变差。中佛罗里达大学和台湾成功大学的研究人员提出了一种最新解决方案，他们采用一种动态色调映射方法来适应人眼对不同照明环境的反应。

In the quest to enhance display readability in bright sunlight, a significant challenge has been maintaining image clarity without compromising other essential aspects such as power consumption and device longevity. Traditional methods have often fallen short, leading to washed-out images that are difficult to see under high ambient light conditions. Researchers at the University of Central Florida and the National Cheng-Kung University in Taiwan have proposed their own novel solution by implementing a dynamic tone mapping method tailored to fit the human eye’s response to different lighting environments.

原始测试图像。(b)在12,000lux光下，使用色调映射和gamma 2.2的测量和模拟图像的比较:情况I(亮度为188尼特)，情况II(亮度为340尼特)和情况III(亮度为566尼特)。色调映射的gamma值在案例一为1.58，案例二为1.83，案例三为2.07。(来源:MDPI)

作者介绍了一种基于环境光强度调整显示器Gamma值的技术。低灰度图像在强光条件下特别不清晰，这种调整可以增强低灰度图像的可见性。通过将Gamma曲线拟合到人眼的功能，该方法动态优化了显示器的可读性，而不会显著增加功耗或牺牲图像质量。

The authors introduce a technique that adjusts the display’s gamma value based on ambient light intensity. This adjustment enhances the visibility of low grayscale images, which are particularly prone to being washed out in bright conditions. By fitting the gamma curve to the human eye’s function, the method dynamically optimizes the display’s readability without significantly increasing power consumption or sacrificing image quality.

为了支持他们的方案，研究人员开发了一种MiniLED背光LCD显示模型，优化了在不同照明条件下的图像质量。该种显示模型确保了背光均匀性一致，这对于保持高质量的图像至关重要。使用该显示模型进行一系列的模拟和优化，结果显示可读性显著改善，特别是对于低灰度内容，经过色调映射调整后，在强光下变得更加清晰和易于区分。

To support their approach, the researchers developed a MiniLED backlit LCD model, which they optimized for image quality under varying lighting conditions. This model ensured consistent backlight uniformity, crucial for maintaining high-quality images. The simulations and optimizations performed with this model demonstrated significant improvements in readability, especially for low grayscale content, which became much clearer and more distinguishable under bright light after applying the tone mapping adjustments.

串联OLED（Tandem OLED）提供高峰值亮度和出色的色彩性能，但高亮度会缩短显示器寿命。MicroLED技术虽然具有精确控制亮度和避免老化的能力，但面临着不均匀性和高制造成本的挑战。研究人员认为，MiniLED背光LCD提供了一种平衡的解决方案，具有高亮度、高温下出色的可靠性和较低的成本。MiniLED背光LCD具有更好的均匀性和耐用性，使其成为在强光下阅读和长期使用的一个理想选择。

Tandem OLEDs offer high peak brightness and excellent color performance but have a shorter lifespan when maintaining high brightness levels. MicroLEDs, although promising with their ability to control brightness precisely and avoid burn-in, face challenges with non-uniformity and high fabrication costs. The researchers make the case that MiniLED backlit LCDs offer a balanced solution with high brightness, excellent reliability at elevated temperatures, and lower costs. They achieve better uniformity and durability, making them ideal for applications requiring high sunlight readability and long-term performance.

利用商用显示面板进行了实验验证，测量了在不同环境光强度下的图像质量。这些实验验证了色调映射方法的有效性。例如，在强光条件下，使用色调映射技术后，低灰度区域的细节，如积雪覆盖的山脉，更加清晰可见。

Experimental validation was carried out using a commercial display panel, measuring image quality under different ambient light intensities. These experiments confirmed the effectiveness of the tone mapping method. For example, in bright light conditions, details in low grayscale areas, such as snow-covered mountains, were more visible after applying the tone mapping technique.

该研究解决了诸如削弱效应（clipping effect）和色偏等潜在问题。通过动态优化Gamma值，色调映射方法减少了这些问题，确保图像即使在强光下也保持清晰和色准。MiniLED背光显示器模型的最佳FWHM/pitch比率为1.2，提供了高背光均匀性，平衡了均匀性和光效率。

The research addressed potential issues such as the clipping effect and color shift. By optimizing the gamma value dynamically, the tone mapping method reduced these issues, ensuring that images remained clear and color-accurate even in intense sunlight. The mini-LED backlit model, with an optimal FWHM/pitch ratio of 1.2, provided high backlight uniformity, balancing uniformity with light efficiency.

参考文献

Qian Y, Chen S-C, Hsiang E-L, Akimoto H, Lin C-L, Wu S-T. Enhancing a Display’s Sunlight Readability with Tone Mapping. Photonics. 2024; 11(6):578. https://doi.org/10.3390/photonics11060578

作者：Joseph Bryans

翻译：SID China