### Visual Quality  
Visual quality is defined as environmental characteristics that are conducive to visual comfort [19]. It is a critical aspect of urban planning [20], playing a vital role in shaping a city's image and significantly enhancing the overall livability of urban areas [21]. Visual comfort serves as a key indicator for measuring visual quality and is one of the quantifiable metrics that directly reflect it. The visual quality of a city greatly influences public appreciation of the urban environment [22].  
In natural landscapes, [PERSON] et al. [23] described and measured visual quality by considering both the visual characteristics and comfort of urban natural landscapes, integrating objective and subjective factors. This research provided urban planners with theoretical support for preserving urban natural landscapes. [PERSON] et al. [24] explored the relationship between plant mechanisms, color, and visual aesthetic quality by studying the colors of vegetation in urban spaces, aiming to enhance the visual quality of urban streets. [PERSON] et al. [25] examined the relationship between the color composition elements of forest landscapes and the estimated scenic beauty values from a macro-perspective, establishing an evaluation framework for assessing the visual quality of forest landscapes.  
In architectural landscapes, numerous studies have focused on the visual quality of various building types, including historic preservation buildings, commercial buildings, and residential structures. These studies examine the relationship between the physical design elements of building facades and visual quality, aiming to enhance the overall visual comfort of urban streets. [PERSON] et al. [26] investigated the balance of visual comfort between new high-rise buildings and historic structures, with the goal of better protecting historic buildings amidst rapid urban development. [PERSON] et al. [19] conducted simulations of light comfort in indoor built environments to explore the relationship between lighting conditions and the visual quality of indoor spaces. Other studies, focusing on aspects such as the visual comfort of advertising signs, plant colors and combinations, and lighting environments [22; 24; 26; 27], propose more targeted strategies--based on the user perspective--to improve regional visual quality.  
[PERSON] et al. [23] explicitly proposed defining and interpreting urban forest aesthetics based on the classification of visual characteristics of urban forests. The correlation between the visual quality of forest colors and the scenic beauty of forests has already been confirmed in previous studies [25]. Additionally, [PERSON] et al. [24] found that street plant landscapes with red hues tend to achieve higher visual landscape quality.  
Previous studies have systematically examined the visual quality of various visual elements. However, old residential buildings, as a significant part of the urban visual landscape [4], have rarely been the focus of color-related visual quality research. Therefore, this study focuses on the colors of aging residential buildings in urgent need of renovation, systematically analyzing the visual quality of their colors.