Abstract. Visual prostheses require an effective representation method due to the limited display condition which has only 2 or 3 levels of grayscale in low resolution. Edges derived from abrupt luminance changes in images carry essential information for object recognition. Typical binary (black and white) edge images have been used to represent features to convey essential information. However, in scenes with a complex cluttered background, the recognition rate of the binary edge images by human observers is limited and additional information is required. The polarity of edges and cusps (black or white features on a gray background) carries important additional information; the polarity may provide shape from shading information missing in the binary edge image. This depth information may be restored by using bipolar edges. We compared object recognition rates from 16 binary edge images and bipolar edge images by 26 subjects to determine the possible impact of bipolar filtering in visual prostheses with 3 or more levels of grayscale. Recognition rates were higher with bipolar edge images and the improvement was significant in scenes with complex backgrounds. The results also suggest that erroneous shape from shading interpretation of bipolar edges resulting from pigment rather than boundaries of shape may confound the recognition.

中文翻译：

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比较视觉假体的二进制和双极边缘图像的物体识别

摘要。由于显示条件有限，在低分辨率下只有 2 或 3 级灰度，因此视觉假肢需要一种有效的表示方法。源自图像亮度突然变化的边缘携带着物体识别的基本信息。典型的二进制（黑白）边缘图像已被用于表示特征以传达基本信息。然而，在具有复杂杂乱背景的场景中，人类观察者对二值边缘图像的识别率是有限的，需要额外的信息。边缘和尖端（灰色背景上的黑色或白色特征）的极性携带重要的附加信息；极性可以根据二进制边缘图像中缺失的阴影信息提供形状。该深度信息可以通过使用双极边缘来恢复。我们比较了 16 个二元边缘图像和 26 位受试者的双极边缘图像的对象识别率，以确定双极滤波在具有 3 个或更多灰度级的视觉假体中可能产生的影响。双极边缘图像的识别率更高，并且在具有复杂背景的场景中改进显着。结果还表明，由颜料而不是形状边界引起的双极边缘的阴影解释所产生的错误形状可能会混淆识别。