It is expected that projector phones (mobile phones with an integrated pico projector) will hit the market in the next few years. So far no research exists regarding how mobile applications should be designed when using a projection and which applications will profit from such a large high-resolution display. This paper presents a comparative evaluation of picture browsing using projector phones. In a study we compared three different interaction techniques: phone display only, projection only and a combination of both. The results show that users prefer the projection-based interaction techniques and the large high-resolution projection leads to a reduced number of enlarge interactions. However, the task completion time results illustrate how familiar users are in using conventional phones with small screen size. The paper presents a comprehensive discussion of findings from our study and defines important guidelines which we consider as critical for the success of applications for projector phones in the future.