Limit the use of colors in the rest of the app if the photograph itself is going to be very colorful.
Use circular crops to reduce the on-screen area that the image takes up, thus drawing less attention to itself.
Consider using color overlays to slightly alter the overall hue of the image in order to better fit with your app's look and feel.
Think about desaturating the image entirely. This way, users can focus on the content of the image without being overwhelmed by its use of color.
Make sure your images have a strong subject and a strong focal point. Without this, your users' eyes will be all over the place and they won't be sure what to look at.
Always have a loading state for the image. This can be as simple as a gradient using the two primary colors of the image infinitely transitioning into each other until the image loads. The only thing worse than using poorly chosen imagery is when nothing at all shows up when the user lands on the screen, leading them to think that the app is broken. Another workaround is to use progressive JPEGs as the file format.