arXiv subjects

Zhenwei Luo

Publications and source records attributed to Zhenwei Luo.

4 recordsLinked to original sources

arXiv2023

Learning depth from monocular video sequences

Learning single image depth estimation model from monocular video sequence is a very challenging problem. In this paper, we propose a novel training loss which enables us to include more images for supervision during the training process. We propose a simple yet effective model to account the frame to frame pixel motion. We also design a novel network architecture for single image estimation. When combined, our method produces state of the art results for monocular depth estimation on the KITTI dataset in the self-supervised setting.

cs.CV↗

arXiv2023

CAMEL2: Enhancing weakly supervised learning for histopathology images by incorporating the significance ratio

Histopathology image analysis plays a crucial role in cancer diagnosis. However, training a clinically applicable segmentation algorithm requires pathologists to engage in labour-intensive labelling. In contrast, weakly supervised learning methods, which only require coarse-grained labels at the image level, can significantly reduce the labeling efforts. Unfortunately, while these methods perform reasonably well in slide-level prediction, their ability to locate cancerous regions, which is essential for many clinical applications, remains unsatisfactory. Previously, we proposed CAMEL, which achieves comparable results to those of fully supervised baselines in pixel-level segmentation. However, CAMEL requires 1,280x1,280 image-level binary annotations for positive WSIs. Here, we present CAMEL2, by introducing a threshold of the cancerous ratio for positive bags, it allows us to better utilize the information, consequently enabling us to scale up the image-level setting from 1,280x1,280 to 5,120x5,120 while maintaining the accuracy. Our results with various datasets, demonstrate that CAMEL2, with the help of 5,120x5,120 image-level binary annotations, which are easy to annotate, achieves comparable performance to that of a fully supervised baseline in both instance- and slide-level classifications.

cs.CV↗

arXiv2020

Improving the resolution of Cryo-EM single particle analysis

We presented a new 3D refinement method for Cryo-EM single particle analysis which can improve the resolution of final electron density map in this paper. We proposed to enforce both sparsity and smoothness to improve the regularity of electron density map in the refinement process. To achieve this goal, we designed a novel type of real space penalty function and incorporated it into the refinement process. We bridged the backprojection step with local kernel regression, thus enabling us to embed the 3D model in reproducing kernel Hilbert space using specific kernels. We also proposed a first order method to solve the resulting optimization problem and implemented it efficiently with CUDA. We compared the performance of our new method with respect to the traditional method on real datasets using a set of widely used metrics for Cryo-EM model validation. We demonstrated that our method outperforms the traditional method in terms of those metrics. The implementation of our method can be found at https://github.com/alncat/cryoem.

eess.IV↗

arXiv2019

Solving Random Systems of Quadratic Equations with Tanh Wirtinger Flow

Solving quadratic systems of equations in n variables and m measurements of the form $y_i = |a^T_i x|^2$ , $i = 1, ..., m$ and $x \in R^n$ , which is also known as phase retrieval, is a hard nonconvex problem. In the case of standard Gaussian measurement vectors, the wirtinger flow algorithm Chen and Candes (2015) is an efficient solution. In this paper, we proposed a new form of wirtinger flow and a new spectral initialization method based on this new algorithm. We proved that the new wirtinger flow and initialization method achieve linear sample and computational complexities. We further extended the new phasing algorithm by combining it with other existing methods. Finally, we demonstrated the effectiveness of our new method in the low data to parameter ratio settings where the number of measurements which is less than information-theoretic limit, namely, $m < 2n$, via numerical tests. For instance, our method can solve the quadratic systems of equations with gaussian measurement vector with probability $\ge 97\%$ when $m/n = 1.7$ and $n = 1000$, and with probability $\approx 60\%$ when $m/n = 1.5$ and $n = 1000$.

math.OC↗