This page was inspired by Alice.C and her narrations about her pet snail Speedy, with the snail equivalent of a 140 IQ. Alice claims the snail has learned to recognize her, and jumps out of its tank to show its emotion.

Original picture from The Apple Snail website, which says that snails have 44 pixel resolution in their visual systems. This probably means a 6x7 grid of photoreceptors, but this does not provide very useful vision, as shown by some of the pictures below. Therefore, we used mostly 40x40 pixel resolution here, as something that might be of practical interest for low-res robotic vision.

original - 200x165 pixels	grey scale - 256 levels
what they said 40 pixel res looks like -(really just hi-res heavily blurred)	actual sample of above at 40x40 pixel resolution

The following images show the results of some simple image-processing transformations on the 40x40 low-res image above. These transforms are based upon the idea that individual visual cells in animals typically have "antagonistic center-surround" receptive fields, where light shown in areas surrounding a central region produce opposite effects to light shown in the central regions. For more info, see: The Computational Eye.

enhance detail	sharpen medium	sharpen heavy
edge enhance	edge detect light	edge detect medium
Alice's kid - what Alice thinks her snail is seeing	what the snail is likely seeing - Calvin [left image] resampled at 6x6 res	original shell resampled at 6x6 res (what the snail likely sees)

For comparison purposes, the following images show the same transforms done on a blurred image. It would appear that heavy blurring may not be as detrimental for low-res vision as one might guess a priori. In other words, a robot using a low-res visual system may not need to worry too much about precisely focussing the images.

Another way of looking at this is that, the images above contain a lot of noise, and it may help successive processing (eg, area boundary definition, continuous surface identification, etc) if this noise were first removed (smoothed). This more or less can be seen by viewing the above images while squinting the eyes.

grey scale - 256 levels	blurred grey scale - 200x165 pixels	blurred - resampled at 40x40 pixels
enhance detail	sharpen medium	sharpen heavy
edge enhance	edge detect light	edge detect medium

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