Each individual eye in the fly's compound eye perceives "on" and "off" contrast changes. This information is split up right behind each individual eye (blue arrow). The L1 cells only transmit information about "on" edges ("light on"), the L2 cells only about "off" edges ("light off") to the output cells (green).
This image may only be used or reproduced for editorial purposes and in connection with scientific articles on our press material, in which case such usage or reproduction is free of charge and requires no permission. Any other use, in particular for commercial purposes, requires prior permission of the author or photographer. Further enquires can be answered in the Press and Public Relations Office - simply write an e-mail to email@example.com.