The study, conducted by researchers at Harvard University and the University of Vermont, analyzed over 43,000 photos posted on Instagram by 166 volunteers. The volunteers were also asked to complete surveys that looked at their social media use, as well as history of mood disorder diagnoses and symptoms of depression.
The results indicated that certain features, such as colour, brightness, and number of faces, of one's online photos may be possible markers for or indicators of depression.
"Those who were depressed tended to post photos with increased hue, decreased brightness, and decreased color saturation. Overall, their photos were “bluer, grayer, and darker.” They also tended to post more frequently and use more Instagram filters, the most popular one for depressed participants being Inkwell, which turns a photo black and white. The most popular filter for volunteers who weren’t depressed was Valencia."
To learn more about the study, click here:
https://arxiv.org/ftp/arxiv/papers/1608/1608.03282.pdf
http://fortune.com/2016/08/22/instagram-diagnose-depression/