Retina-like sensor is a kind of anthropomorphic visual sensor, which mimic the distribution of photoreceptors in the human retina. They are applied in fields of machine vision and target tracking. However, there are few reports on retina-like sensor used for forward-motion imaging. During forward-motion imaging, as the objects being imaged move along the optical axis direction during the integration time, image quality becomes worse towards the border of the image. In order to get clearer image, retina-like sensor are trying to be designed based on the feature of forward-motion imaging. In this paper, firstly, the degraded law of rectilinear sensor used for forward-motion imaging is analyzed, the retina-like sensor model based on the feature of forward-motion imaging are proposed. Secondly, the output image of retina-like sensor and rectilinear sensor used during the forward-motion imaging for different scenes at different degeneration degrees are simulated, respectively. Thirdly, the simulated images of both two sensors are assessed by four different image quality assessment methods including visual information fidelity (VIF), complex wavelet structural similarity index (CW-SSIM), Gabor filtered image contrast similarity (GFCS) and peak signal to noise ratio (PSNR), besides, the data amount of two sensors are compared. Four image quality assessments all demonstrate that image quality of retina-like sensor based on the feature of forward motion imaging is superior to that of rectilinear sensor.
Retina_like sensor is characterized by a space-variant resolution mimicking the distribution of photoreceptors in the human retina. It is devided into two areas-the central area and the peripheral area. Density of pixels is highest in the center and decreases monotonically toward the periphery area. Such space-varant image allows high-resolution tasks using the central region while maintaining a lower resolution part providing relevant information about the background. In high speed forward motion field, because the image system is approaching or leaving the object in a high speed, the recorded image will be blurred radially. However, this kind of radial blur can be reduced by changing the pixel layout of retina_like sensor. So image quality assessment studies carried out on the different structures of the retina_like sensor output image can provide theoretical guidance for the establishment of the optimal layout of the retina_like sensor. This paper first analyzes the distortion process of the retina_like sensor output image in high-speed forward motion and find that such a distortion of the image including under-sampled distortion and radial blur distortion. Based on the characteristics of the distorted image, the author puts forward a full reference image quality assessment method, named Qretina, for such images. The method is according to the distortion process. Do under-sampling evaluation and radial fuzzy evaluation firstly, then weigh the two parts to get the final image quality evaluation results. The experimental results show that Qretina has better performance than the SSIM.