Linking the Retina to the Natural World (IMAGE) University of Pennsylvania Caption Image of dandelions rectified into separate channels for bright (ON) and dark (OFF) contrasts. More intense pixels correspond to stronger contrasts. Following rectification, highlights appear bright in the ON image and dark in the OFF image. Credit University of Pennsylvania Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.