Smartphones have backlit screens that can make some photos appear quite bright. Most of your photos will be printed without any difference. However, it is advisable to enhance the shadow and brightness of your dark or high-contrast photos.
To do this, you can use your device's photo editor or your favourite app. Our favouyrites are VSCO and Snapseed because they are easy to use and free! However, any editor with shadow/highlight adjustment tools can be used. You can use 'Brightness' or 'Highlights' to increase the light in an image or 'Shadows' to enhance dark areas only. 'Contrast' also helps. Exposure will have an effect on overall exposure.
The goal here is to get a well-balanced image before printing to achieve a perfect result. Unless you like the dramatic look! 😎