论文标题
插件压缩感应的精确且可靠的恢复
On Exact and Robust Recovery for Plug-and-Play Compressed Sensing
论文作者
论文摘要
在插件播放(PNP)算法中,使用现成的DeOiser用于图像正则化。 PNP产生最新的结果,但其理论方面尚未得到充分理解。这项工作考虑了一个问题:类似于经典的压缩感测(CS),理论上我们是否可以在DeOiser和传感矩阵的适当条件下通过PNP恢复地面真相?一个障碍是,由于PNP是一个算法框架,因此其解决方案不必是某些目标函数的最小化器。最近显示的是,凸正则$φ$可以与一类线性denoisiser相关联,因此PNP等于解决涉及$φ$的凸问题。由此激励,我们考虑了CS的PNP类似物:最小化$φ(x)$ s.t.。 $ ax =aξ$,其中$ a $是$ m \ times n $随机传感矩阵,$φ$是与线性denoiser $ w $相关的常规器,而$ξ$是地面真相。我们证明,如果$ a $是高斯,而$ξ$在$ w $的范围内,那么如果$ rank(w)\ leq m $,则肯定是$ξ$,并且如果$ rank(w)> m $ nver nyver nyver。因此,PNP DeOiser的范围是先验的信号,其尺寸标志着从失败到精确恢复成功的急剧过渡。我们将结果扩展到Subgaussian感应矩阵,只是精确的恢复仅具有很高的概率。对于嘈杂的测量值$ b = ament+η$,我们考虑了一个健壮的配方:最小化$φ(x)$ s.t.。 $ \ | ax-b \ | \leqδ$。我们证明,对于最佳解决方案$ x^*$,具有高概率,失真$ \ | x^* - ξ\ | $由$ \ |η\ | $和$δ$限制,如果测量数足够大。特别是,我们可以得出CS的样品复杂性,这是失真误差和成功率的函数。我们讨论了这些结果的扩展到随机的傅立叶测量,执行数值实验,并讨论了这项工作引起的研究方向。
In Plug-and-Play (PnP) algorithms, an off-the-shelf denoiser is used for image regularization. PnP yields state-of-the-art results, but its theoretical aspects are not well understood. This work considers the question: Similar to classical compressed sensing (CS), can we theoretically recover the ground-truth via PnP under suitable conditions on the denoiser and the sensing matrix? One hurdle is that since PnP is an algorithmic framework, its solution need not be the minimizer of some objective function. It was recently shown that a convex regularizer $Φ$ can be associated with a class of linear denoisers such that PnP amounts to solving a convex problem involving $Φ$. Motivated by this, we consider the PnP analog of CS: minimize $Φ(x)$ s.t. $Ax=Aξ$, where $A$ is a $m\times n$ random sensing matrix, $Φ$ is the regularizer associated with a linear denoiser $W$, and $ξ$ is the ground-truth. We prove that if $A$ is Gaussian and $ξ$ is in the range of $W$, then the minimizer is almost surely $ξ$ if $rank(W)\leq m$, and almost never if $rank(W)> m$. Thus, the range of the PnP denoiser acts as a signal prior, and its dimension marks a sharp transition from failure to success of exact recovery. We extend the result to subgaussian sensing matrices, except that exact recovery holds only with high probability. For noisy measurements $b = A ξ+ η$, we consider a robust formulation: minimize $Φ(x)$ s.t. $\|Ax-b\|\leqδ$. We prove that for an optimal solution $x^*$, with high probability the distortion $\|x^*-ξ\|$ is bounded by $\|η\|$ and $δ$ if the number of measurements is large enough. In particular, we can derive the sample complexity of CS as a function of distortion error and success rate. We discuss the extension of these results to random Fourier measurements, perform numerical experiments, and discuss research directions stemming from this work.