OF THE millions of photos shared online every day, which most faithfully represent their subjects? The popular #nofilter hashtag would suggest it is those that have not been digitally altered. But photographs of the same thing can differ greatly, depending on ambient light, distance and angle. So the right manipulation can actually make a picture more honest—and therefore more useful medically.
That is the idea behind an app from Healthy.io, an Israeli firm. Dip.io uses mobile-phone cameras for clinical-grade urine analysis. The patient follows the instructions, waits for the colours on the dipstick to develop and then takes a picture of it against the background of a proprietary colour card. The app uses the card to correct the colours so that the dipstick appears as if in a neutral, standard ambient light.