Generative text-to-image models, which allow users to create appealing images through a text prompt, have seen a dramatic increase in popularity in recent years. However, most users have a limited understanding of how such models work and it often requires many trials and errors to achieve satisfactory results. The prompt history contains a wealth of information that could provide users with insights into what have been explored and how the prompt changes impact the output image, yet little research attention has been paid to the visual analysis of such process to support users. We propose the Image Variant Graph, a novel visual representation designed to support comparing prompt-image pairs and exploring the editing history. The Image Variant Graph models prompt differences as edges between corresponding images and presents the distances between images through projection. Based on the graph, we developed the PrompTHis system through co-design with artists. Besides Image Variant Graph, PrompTHis also incorporates a detailed prompt-image history and a navigation mini-map. Based on the review and analysis of the prompting history, users can better understand the impact of prompt changes and have a more effective control of image generation. A quantitative user study with eleven amateur participants and qualitative interviews with five professionals and one amateur user were conducted to evaluate the effectiveness of PrompTHis. The results demonstrate PrompTHis can help users review the prompt history, make sense of the model, and plan their creative process.

翻译：生成式文本到图像模型使用户能够通过文本提示创建吸引人的图像，近年来其普及度急剧上升。然而，大多数用户对这些模型的工作原理理解有限，通常需要多次试错才能获得满意结果。提示历史中蕴含丰富信息，可帮助用户了解已探索的内容以及提示变化如何影响输出图像，但针对此类过程的视觉分析以支持用户的研究尚不多见。我们提出图像变体图（Image Variant Graph），这是一种新颖的可视化表示，旨在支持比较提示-图像对并探索编辑历史。图像变体图将提示差异建模为对应图像之间的边，并通过投影呈现图像间的距离。基于该图，我们通过与合作艺术家的协同设计开发了PrompTHis系统。除图像变体图外，PrompTHis还包含详细的提示-图像历史记录和导航小地图。通过回顾与分析提示历史，用户能更清晰地理解提示变化的影响，从而更有效地控制图像生成。我们开展了一项包含11名业余参与者的定量用户研究，并对5名专业人士和1名业余用户进行了定性访谈，以评估PrompTHis的有效性。结果表明，PrompTHis能帮助用户回顾提示历史、理解模型机制并规划创作过程。