The freedom of design of coded masks used by mask-based lensless cameras is an advantage these systems have when compared to lens-based ones. We leverage this freedom of design to propose a shape-preserving optimization scheme for a radial-type amplitude coded mask. Due to the depth-independency of the radial mask's point spread function, they can be used for extending the effective depth of field (DOF) of a lensless imaging system. In this article we optimized a coded mask for improved frequency response, while retaining its radial characteristics and therefore extended-DOF capabilities. We show that our optimized radial mask achieved better overall frequency response when compared to naive implementations of a radial mask. We also quantitatively and qualitatively demonstrated the extended DOF imaging achieved by our optimized radial mask in simulations by comparing it to different non-radial coded masks. Finally, we built a prototype camera to validate the extended DOF capabilities of our coded mask in real scenarios.

中文翻译：

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使用优化的径向掩模的扩展景深无透镜成像

与基于镜头的系统相比，基于掩模的无镜头相机所使用的编码掩模的设计自由度是这些系统的一个优势。我们利用这种设计自由度，提出了一种用于径向型幅度编码掩模的形状保持优化方案。由于径向掩模的点扩散函数与深度无关，它们可用于扩展无透镜成像系统的有效景深 (DOF)。在本文中，我们优化了编码掩模以改善频率响应，同时保留其径向特性，从而保留其扩展自由度功能。我们表明，与径向掩模的简单实现相比，我们优化的径向掩模实现了更好的整体频率响应。我们还通过将优化的径向掩模与不同的非径向编码掩模进行比较，定量和定性地展示了在模拟中通过优化的径向掩模实现的扩展自由度成像。最后，我们构建了一个原型相机来验证我们的编码掩模在真实场景中的扩展 DOF 功能。