1. A method comprising: receiving information about a story for presentation to a user of a social networking system, the story comprising an image and text associated with the image; computing a readability score for a combination of the image and the text, the readability score indicating measure of a likelihood of the user reading the text when overlaid onto the image and the readability score based at least in part on one or more attributes of the image, one or more attributes of the text, or any combination thereof; generating the story including the text and the image where the text is overlaid onto an area of the image if the readability score for the combination of the image and the text satisfies a condition; and sending the story for display to the user.