The photos you share online speak volumes. They can serve as a form of self-expression or a record of travel. They can reflect your style and your quirks. But they might convey even more than you realize: The photos you share may hold clues to your mental health, new research suggests.

From the colors and faces in their photos to the enhancements they make before posting them, Instagram users with a history of depression seem to present the world differently from their peers, according to the study, published this week in the journal EPJ Data Science.

“People in our sample who were depressed tended to post photos that, on a pixel-by-pixel basis, were bluer, darker and grayer on average than healthy people,” said Andrew Reece, a postdoctoral researcher at Harvard University and co-author of the study with Christopher Danforth, a professor at the University of Vermont.