一种视觉假体的视觉显著图提取新方法

A new method for extracting visual saliency map for visual prosthesis

目的 一幅图像或场景的显著性区域代表它们的主要内容（显著目标）.由于视觉假体可植入电极的数量有限,只有低分辨率的图像对其才有用,因此提取显著性区域有助于视觉假体捕捉到场景中的显著目标.方法 Itti模型是一个显著性检测模型,它检测到的显著性区域与人的视觉感知有差异,显著目标的边界不明确.笔者去除了Itti模型提取的方向和色彩特征,将红（R）、绿（G）、蓝（B）三基色（RGB）图像转换到对应于HSI颜色空间上的色调（H）、纯度（S）、亮度（I）3个新特征分量,对hti模型进行优化改进.在显著图中,将落在显著目标内的显著点面积与总显著点面积的比值定义为显著图精确度;以显著图精确度为提取显著图方法的测度,对改进前后2种方法进行比较.结果 利用改进方法提取的显著图比Itti模型显著图精确度提高了约20％;在检测显著性区域时所用时间减少近50％.结论 提出了一种用于人工视觉的获取显著目标的方法,本算法可以得到更加精确的显著性结果,且可缩短运行时间.

Objective Salient regions may express the main content （salient objects） in an image or scene.Since the number of implanted electrodes for visual prosthesis is limited,only the low-resolution image is used.Extraction of the salient regions may help capture salient objects in the scenes of visual prosthesis.Methods Salient regions detected by Itti model,one of salient detection models,have some differences with human visual perceptions and its salient objects boundary are also unclear.The Itti model was optimized by removing the orientation and the color characteristics,and converting the RGB image in an image or scene into the HSI color space with three new feature components of hue,saturation and intensity.In saliency map,the ratio of the salient point area in salient objects regions and the total salient point area was defined as salient accuracy and computed,which was used to compare the effects of the two methods of extracting salient map.Results Compared with the Itti method for extracting saliency map,the salient accuracy of the improved method was increased by about 20％,and the time for detecting the same salient regions by our method was shorter by nearly 50％.Conclusions The proposed algorithm can be an alternative method to extract salient map from a complex image or scene for retinal prosthesis with higher salient accuracy and less running time.