By omitting external lighting, OLED display significantly reduces the power draw compared to its predecessor LCD and has gained wide adoption in modern smartphones. The real potential of OLED in saving phone battery drain lies in exploiting app UI color design, i.e., how to design app UI to use pixel colors that result in low OLED display power draw. In this paper, we design and implement an accurate per-frame OLED display power profiler, PFOP, that helps developers to gain insight into the impact of different app UI design on its OLED power draw, and an enhanced Android Battery that helps phone users to understand and manage phone display energy drain, for example, from different app and display configurations such as dark mode and screen brightness. A major challenge in designing both tools is to develop an accurate and robust OLED display power model. We experimentally show that linear-regression-based OLED power models developed in the past decade cannot capture the unique behavior of OLED display hardware in modern smartphones which have a large color space and propose a new piecewise power model that achieves much better modeling accuracy than the prior-art by applying linear regression in each small regions of the vast color space. Using the two tools, we performed to our knowledge the first power saving measurement of the emerging dark mode for a set of popular Google Android apps.

In today's digital age, excessive screen time has become a widespread concern, leading to health problems like eye strain and disrupted sleep patterns. To tackle this issue and optimize the use of mobile device resources, we propose an innovative system that monitors users' screen time and automatically activates Dark Mode when predefined time limits are exceeded. The proposed system offers user customization, allowing individuals to set their preferred time limits, giving them control over their digital habits. When a user surpasses their set screen time limit, the proposed system alert user to seamlessly switches to Dark Mode. By reducing screen brightness and other power-intensive features in Dark Mode, it helps conserve battery life, reduce heat generation, and prolong device lifespan. The Applicaion successfully integrates with a user-friendly interface with a timed notification system, effectively encouraging users to consider and implement Dark Mode for their device display. Additionally, by promoting focused and efficient screen usage, it minimizes unnecessary data consumption. Through this system, users can experience reduced eye strain, better sleep, extended battery life, and improved overall digital well-being through this innovative solution. The application's seamless integration with Android 13 and its responsiveness on the specified device specifications validate its practicality and usability.