Insects can see with much higher resolution than thought

Insects have much better vision and can see in far greater detail by generating images of higher resolution than previously thought, scientists say.
It has been long believed that insects can not see fine images. This is because their compound eyes typically consist of thousands of tiny lens-capped 'eye-units', which together should capture a low-resolution pixelated image of the surrounding world.
Researchers from the University of Sheffield in the UK have now discovered that insect compound eyes can also generate surprisingly high-resolution images, and that this has much to do with how the photo receptor cells inside the compound eyes react to image motion.

To record these movements inside intact insect eyes during light stimulation, the researchers had to build a microscope with a high-speed camera system.
They also found that the way insect compound eye samples an image is tuned to its natural visual behaviours.
By combining their normal head/eye movements - as they view the world in saccadic bursts - with the resulting light- induced microscopic photo receptor cell twitching - insects, such as flies can resolve the world in much finer detail than was predicted by their compound eye structure, giving them hyperacute vision, researchers said.

The team found that photo receptors resolve small moving objects, even at high speeds, far better than predicted by compound eye optics and reveal the mechanisms behind this remarkable hyperacuity.

"By using electro physiological, optical and behavioural assays with mathematical modelling we have demonstrated that fruit flies (Drosophila) have much better vision than scientists have believed for the past 100 years," said Mikko Juusola, professor at University of Sheffield.
From humans to insects, all animals with good vision, irrespective of their eye shape or design, see the world through fast saccadic eye movements and gaze fixations, said Juusola.
"Our results suggest that by adapting the way photo receptor cells sample light information to saccadic eye movements and gaze fixations, evolution works towards optimising the visual perception of animals," Juusola added.

The study was published in the journal eLife.