The coded aperture snapshot spectral imager (CASSI) is a computational imaging system that acquires a three dimensional (3D) spectral data cube by a single or a few two dimensional (2D) measurements. The 3D data cube is reconstructed computationally. Binary on-off random coded apertures with square pixels are primarily implemented in CASSI systems to modulate the spectral images in the image plane. The design and optimization of coded apertures have been shown to improve the imaging performance of these systems significantly. This work proposes a different approach to code design. Instead of traditional squared tiled coded elements, hexagonal tiled elements are used. The dislocation between the binary hexagonal coded apertures and the squared detector pixels is shown to introduce an equivalent grey-scale spatial modulation that increases the degrees of freedom in the sensing matrix, thus further improving the spectral imaging performance. Based on the restricted isometry property (RIP) of compressive sensing theory, this article derives optimal coded aperture patterns under a hexagonal lattice which obey blue noise spatial characteristics, where “on” elements are placed as far from each other as possible. In addition, optimal coded apertures used in different snapshots are complementary to each other. The superiority of hexagonal blue noise coded apertures over the traditional coded apertures with squared tiled elements is shown.

中文翻译：

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基于六边形蓝色噪声编码孔径的压缩光谱成像


编码孔径快照光谱成像仪 (CASSI) 是一种计算成像系统，可通过单个或几个二维 (2D) 测量获取三维 (3D) 光谱数据立方体。 3D 数据立方体通过计算重建。具有方形像素的二进制开关随机编码孔径主要在 CASSI 系统中实现，以调制图像平面中的光谱图像。编码孔径的设计和优化已被证明可以显着提高这些系统的成像性能。这项工作提出了一种不同的代码设计方法。使用六边形平铺元件代替传统的方形平铺编码元件。二进制六边形编码孔径和平方探测器像素之间的错位引入了等效的灰度空间调制，增加了传感矩阵的自由度，从而进一步提高了光谱成像性能。基于压缩感知理论的受限等距特性（RIP），本文推导了六方晶格下服从蓝噪声空间特性的最佳编码孔径图案，其中“on”元件彼此放置得尽可能远。此外，不同快照中使用的最佳编码孔径是互补的。显示了六边形蓝色噪声编码孔径相对于具有方形平铺元件的传统编码孔径的优越性。