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arXiv 2112.05855math.NAcs.NA
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二值图像带限离散傅里叶变换的反演:唯一性与算法

Inversion of band-limited discrete Fourier transforms of binary images: Uniqueness and algorithms

Howard W. Levinson, Vadim A. Markel, Nicholas Triantafillou

AI总结:

针对二值图像高频DFT系数缺失导致恢复不唯一的问题,本文利用二值约束,理论证明唯一恢复的最小带限,并提出结合整数线性规划与格基约简的算法,可仅用121个系数可靠重建29×29模糊矩阵。

摘要:

离散傅里叶变换(DFT)的传统反演要求所有DFT系数已知。当栅格化图像(表示为矩阵)的DFT系数仅在通带内已知时,原始矩阵无法被唯一恢复。在许多实际重要情形中,矩阵是二值的,其元素可简化为0或1。例如,常用的QR码即属此类。矩阵为二值这一先验信息可以弥补缺失的高频DFT系数,并恢复图像恢复的唯一性。本文从理论和数值两方面研究了在利用二值约束的条件下,恢复无已知结构且高频DFT系数已不可逆丢失的模糊图像的问题。我们从理论上探究了仍能实现一般二值矩阵唯一恢复的最小带限。对于尺寸为$N_1 \times N_2$、$N_1 \times N_1$和$N_1^\alpha\times N_1^\alpha$的图像(其中$N_1 \neq N_2$为素数,$\alpha>1$为整数),证明了唯一性结果。提出了从带限(模糊)版本恢复矩阵的反演算法。这些算法将整数线性规划方法与格基约简技术相结合,显著优于朴素实现。该算法能高效可靠地重建严重模糊的$29 \times 29$二值矩阵,仅需$11\times 11 = 121$个DFT系数。

英文摘要:

Conventional inversion of the discrete Fourier transform (DFT) requires all DFT coefficients to be known. When the DFT coefficients of a rasterized image (represented as a matrix) are known only within a pass band, the original matrix cannot be uniquely recovered. In many cases of practical importance, the matrix is binary and its elements can be reduced to either 0 or 1. This is the case, for example, for the commonly used QR codes. The {\it a priori} information that the matrix is binary can compensate for the missing high-frequency DFT coefficients and restore uniqueness of image recovery. This paper addresses, both theoretically and numerically, the problem of recovery of blurred images without any known structure whose high-frequency DFT coefficients have been irreversibly lost by utilizing the binarity constraint. We investigate theoretically the smallest band limit for which unique recovery of a generic binary matrix is still possible. Uniqueness results are proved for images of sizes $N_1 \times N_2$, $N_1 \times N_1$, and $N_1^α\times N_1^α$, where $N_1 \neq N_2$ are prime numbers and $α>1$ an integer. Inversion algorithms are proposed for recovering the matrix from its band-limited (blurred) version. The algorithms combine integer linear programming methods with lattice basis reduction techniques and significantly outperform naive implementations. The algorithm efficiently and reliably reconstructs severely blurred $29 \times 29$ binary matrices with only $11\times 11 = 121$ DFT coefficients.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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