![]() Emerging technologies such as scanning laser display or OLED may provide better alternatives. ![]() While we were able to achieve the required registration 16, the brightness of the edges that could be achieved with the existing LCD display technology was insufficient to provide a beneficial enhancement effect. We, therefore, have developed and evaluated (in conjunction with MicroOptical Engineering, Inc., Westwood, MA) a system in which the same optical path is used for the camera acquiring the images and for the display presenting the edges derived from it. It is critical in this application to achieve accurate registration between the natural view seen through the display and the edge images presented on the display. In this application only unipolar (white) edges can be used as it is not possible to implement a black edge on the optical see-through display. We have also proposed the use of the wideband enhancement in a see-through HMD as a way to provide augmented vision – by enhancing the view of the real world. The features brightness can be adjusted to increase or decrease the level of enhancement. Note the white line on the woman’s left arm. (b) The bipolar features added to the original image. (a) Bipolar features (edges and bars) detected from the original image are scaled according to the strength of the feature. Following a set of pilot experiments we selected a process whereby outlines detected in the image were added to the original image at their locations and were scaled in magnitude according to the strength of the feature at the location. In both cases the outline magnitudes can be fixed or variable. Bright and dark lines can replace (substitute) the original pixels values at their corresponding locations or they can be added (subtracted for dark lines) to the original pixels’ values. The feature’s outlines detected by the algorithm may be used to enhance the visibility of the features they underlie. Thin “bar” features are represented with a single, appropriate polarity line at the location of the bar. This algorithm marks “edge” features with dual polarity pairs of bright and dark lines with the bright line on the bright side of the edge and the dark line on the dark side of the edge. The edge detection algorithm used for the wideband enhancement is a dual polarity edge detector based on a vision model 15 ( Fig. The wideband image enhancement consists of locating visually relevant features in the image (edges and bars) and enhancing the contrast of the pixels of such features 14. However, this approach was never formally tested to demonstrate its effectiveness since there was no clear way to assess the value of such system for mobility. To reduce the cost, weight, and power consumption, a one dimensional (1-D) analog video processing alternative was designed and implemented 13. We adapted it as a portable low vision image enhancement aid. While the face is clearly recognizable, the severe distortion caused by the enhancement is apparent and is noted by the patients.Īn early head mounted display (HMD) system, the Private Eye, was a binary display device that used scanning red LEDs to form the image 12. An example of a face image enhanced with adaptive thresholding is shown in Fig. The size of the local neighborhood used in processing the local properties determines the range of spatial frequencies that are enhanced by the adaptive thresholding. ![]() The binary image has inherent high contrast and if it maintains the relevant image’s information in a satisfactory way, it may be useful as an enhancement technique.Īdaptive thresholding changes the threshold applied across the image as a function of local image properties 10, 11. ![]() Adaptive or local thresholding that results in binary images is not commonly considered as an enhancement technique, but may serve as such especially for visually impaired patients. ![]()
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