Video processing methods for improving visual acuity and/or perceived image resolution
A method and apparatus for improving visual acuity when providing a visual image from a “high” resolution input device to a “low” resolution output device. The described invention is of particular use when the output device is an array of electrodes as part of a retinal prosthesis used to restore vision to a visually-impaired patient. In that various limitations may, within the foreseeable future, limit the density of such an electrode array (and thus the resolution of the output image), the present invention teaches techniques to assign processed pixel subsets of a higher resolution image to a single electrode. By varying the pixel subsets, e.g., by jittering, and/or altering the processing criteria, the perceived visual acuity may be further improved. Alternatively and additionally, such processing may be further extended to drive neighboring electrodes in combination to thus stimulate virtual electrode sites and thus further enhance visual acuity.
1. A visual prosthesis comprising:
a high resolution video input device;
a lower resolution array of electrodes;
a video processing unit receiving a high resolution image from the high resolution video input device, alternatively
a. mapping a subset of pixels from the high resolution video input device to electrodes in the lower resolution array of electrodes and driving electrodes in said lower resolution electrode array according to said subset of pixels to create a first set visual percepts, or
b. mapping a second subset of pixels from said high resolution video input device to pairs of electrodes in the lower resolution array of electrodes and driving said pairs of electrodes in said lower resolution electrode array according to said second subset of pixels to create a second set of visual percepts at locations physically displaced from said pairs of electrodes;
whereby the perceived visual acuity is increased.
2. The visual prosthesis according to claim 1 , wherein said second set of visual percepts fall between said pairs of electrodes.
3. The visual prosthesis according to claim 1 , wherein said video processing unit periodically alters between said first subset and said second subset of input pixels.
4. The visual prosthesis according to claim 3 , wherein said video processing unit periodically alters between said first subset and said second subset of input pixels on a regular basis.
5. The visual prosthesis according to claim 3 , wherein said video processing unit periodically alters between said first subset and said second subset of input pixels on a pseudo-random basis.
6. The visual prosthesis according to claim 3 , wherein said video processing unit periodically alters between said first subset and said second subset of input pixels according to sensed eye movement.
7. The visual prosthesis according to claim 3 , wherein said video processing unit periodically alters between said first subset and said second subset of input pixels according to a patient selectable input.