Multi-electrode devices are constantly evolving toward a state where complexity and reliability are adequate for providing a breakthrough in visual cortical stimulation allowing the blind to recover partial vision. Yet few research teams have focused on the development of the front-end subsystem that transforms an input image from a camera into stimulation commands. This article collects state-of-the-art knowledge about the appearance and organization of phosphenes, and previous work in image processing dedicated to visual cortical stimulation. Observations and hypothesis about important issues are highlighted, and six image processing strategies that could be used in such a subsystem are presented, from the most optimistic that use brightness modulation to emulate grayscale to the most conservative that use only on/off phosphene evocation.

No abstract

Many research teams are currently investigating on visual cortical stimulation in order to allow the blind to recover partial vision. Reliable multi-electrode stimulators are needed for a breakrhrough in this research field. The next step towards these medical devices is to develop the front-end subsystem that transforms an input image from a camera to stimulator commands. This task is not obvious, since organization and appearance ojphosphenes is not uniform and still based on many hypothesis. The paper discusses about these issues, and proposes a front-end subsystem constituted by an image processing system, along with a visualization sofrware that attempts to represent what a blind would perceive when stimulated in accordance to the output ojthe subsystem. An approach focusing on the edges of images is privileged Theprocessing sJ'stem itser is still in development, but its functionali@ is presented