Social media images, curated or casual, have become a crucial component of communicating situational information and emotions during health crises. Despite its prevalence and significance in informational dissemination and emotional connection, there lacks a comprehensive understanding of visual crisis communication in the aftermath of a pandemic which is characterized by uncertain local situations and emotional fatigue. To fill this gap, this work collected 345,423 crisis-related posts and 65,376 original images during the Xi'an COVID-19 local outbreak in China, and adopted a mixed-methods approach to understanding themes, goals, and strategies of crisis imagery. Image clustering captured the diversity of visual themes during the outbreak, such as text images embedding authoritative guidelines and ``visual diaries'' recording and sharing the quarantine life. Through text classification of the post that visuals were situated in, we found that different visual themes highly correlated with the informational and emotional goals of the post text, such as adopting text images to convey the latest policies and sharing food images to express anxiety. We further unpacked nuanced strategies of crisis image use through inductive coding, such as signifying authority and triggering empathy. We discuss the opportunities and challenges of crisis imagery and provide design implications to facilitate effective visual crisis communication.

翻译：社交媒体图像，无论是精心拍摄还是随手记录，已成为健康危机期间传递情境信息与情感的关键载体。尽管其在信息传播和情感连接中普遍存在且至关重要，但在以不确定局部情境和情感疲劳为特征的疫情后期，视觉危机传播仍缺乏系统性理解。为弥补这一空白，本研究收集了中国西安新冠局部疫情期间的345,423条危机相关帖文及65,376张原始图像，采用混合方法探究危机图像的主题、目标与策略。图像聚类揭示了疫情期间视觉主题的多样性，例如嵌入权威指导的文本图像，以及记录和分享隔离生活的"视觉日记"。通过图像所在帖文的文本分类，我们发现不同视觉主题与帖文文本的信息性及情感性目标高度相关，例如利用文本图像传达最新政策、分享食物图像表达焦虑。通过归纳编码，我们进一步解析了危机图像使用的精细策略，如权威表征与共情触发。本文讨论了危机图像的机遇与挑战，并提出了促进高效视觉危机传播的设计启示。