The Impact of Curviness on Four Different Image Sensor Forms and Structures.

Wei Wen,Siamak Khatibi

doi:10.3390/s18020429

Abstract

The arrangement and form of the image sensor have a fundamental effect on any further image processing operation and image visualization. In this paper, we present a software-based method to change the arrangement and form of pixel sensors that generate hexagonal pixel forms on a hexagonal grid. We evaluate four different image sensor forms and structures, including the proposed method. A set of 23 pairs of images; randomly chosen, from a database of 280 pairs of images are used in the evaluation. Each pair of images have the same semantic meaning and general appearance, the major difference between them being the sharp transitions in their contours. The curviness variation is estimated by effect of the first and second order gradient operations, Hessian matrix and critical points detection on the generated images; having different grid structures, different pixel forms and virtual increased of fill factor as three major properties of sensor characteristics. The results show that the grid structure and pixel form are the first and second most important properties. Several dissimilarity parameters are presented for curviness quantification in which using extremum point showed to achieve distinctive results. The results also show that the hexagonal image is the best image type for distinguishing the contours in the images.

Highlights

The arrangement and form of photoreceptors vary from the fovea to the periphery of the retina.This is a consequence of evolution which argues that the arrangement and form of camera pixel sensors should be variable as well
The results indicate that the SQ image type detects more common saddle points; in 87% of straight contour (SC) and curved contour (CC) image pairs, and Hexagonal Enriched Image (Hex_E) image type detects more extremum points; in 74% of image pairs
We present a software-based method to generate images with hexagonal pixel form

Summary

Introduction

The arrangement and form of photoreceptors vary from the fovea to the periphery of the retina.This is a consequence of evolution which argues that the arrangement and form of camera pixel sensors should be variable as well. Previous works [3,4] have shown the feasibility of converting the rectangular to hexagonal grid structure by a half pixel shifting method (i.e., a software-based approach). The rectangular grid can be suppressed in rows and columns alternatively and be sub-sampled; i.e., by a half-pixel shifting method [11]. In this way, a bigger hexagonal pixel is generated at the cost of obtaining lower resolution in comparison to the original rectangular grid. Between rows is changed by 3/2 and the pixel shifting can be achieved e.g., by implementing normalized convolution [12] The significances of such a structure are the equidistant and 60 degrees intersection of the sampling points. In Yabushita et al [5], the pseudohexagonal elements are composed of small square pixels with an aspect ratio of 12:14, which was later implemented by Jeevan et al

Methods

Results

Conclusion