When a social networking system receives an image and associated text for presentation to one or more users, the social networking system determines how to present the text and the image. For example, the social networking system determines if to overlay the text onto an area of the image. A readability score indicating the readability of the text if overlaid onto an area of the image is determined based on attributes of the image and of the text. Using the readability score, the social networking system overlays the text onto an area of the image when presented to other users or presents the text adjacent to the image when presented to other users.