22 research outputs found
An Alarm System For Segmentation Algorithm Based On Shape Model
It is usually hard for a learning system to predict correctly on rare events
that never occur in the training data, and there is no exception for
segmentation algorithms. Meanwhile, manual inspection of each case to locate
the failures becomes infeasible due to the trend of large data scale and
limited human resource. Therefore, we build an alarm system that will set off
alerts when the segmentation result is possibly unsatisfactory, assuming no
corresponding ground truth mask is provided. One plausible solution is to
project the segmentation results into a low dimensional feature space; then
learn classifiers/regressors to predict their qualities. Motivated by this, in
this paper, we learn a feature space using the shape information which is a
strong prior shared among different datasets and robust to the appearance
variation of input data.The shape feature is captured using a Variational
Auto-Encoder (VAE) network that trained with only the ground truth masks.
During testing, the segmentation results with bad shapes shall not fit the
shape prior well, resulting in large loss values. Thus, the VAE is able to
evaluate the quality of segmentation result on unseen data, without using
ground truth. Finally, we learn a regressor in the one-dimensional feature
space to predict the qualities of segmentation results. Our alarm system is
evaluated on several recent state-of-art segmentation algorithms for 3D medical
segmentation tasks. Compared with other standard quality assessment methods,
our system consistently provides more reliable prediction on the qualities of
segmentation results.Comment: Accepted to ICCV 2019 (10 pages, 4 figures
KNOWLEDGE FUSION IN ALGORITHMS FOR MEDICAL IMAGE ANALYSIS
Medical imaging is one of the primary modalities used for clinical diagnosis and treatment planning. Building up a reliable automatic system to assist clinicians read the enormous amount of images benefits the efficiency and accuracy in general clinical trail. Recently deep learning techniques have been widely applied on medical images, but for applications in real clinical scenario, the accuracy, robustness, interpretability of those algorithms requires further validation.
In this dissertation, we introduce different strategies of knowledge fusion for improving current approaches in various tasks in medical image analysis. (i) To improve the robustness of segmentation algorithm, we propose to learn the shape prior for organ segmentation and apply it for automatic quality assessment. (ii) To detect pancreatic lesion with patient-level label only, we propose to extract shape and texture information from CT scans and combine them with a fusion network. (iii) In image registration, semantic information is important yet hard to obtain. We propose two methods for introducing semantic knowledge without the need of segmentation label. The first one designs a joint framework for registration synthesis and segmentation to share knowledge between different tasks. The second one introduces unsupervised semantic embedding to improve regular registration framework. (iv) To reduce the false positives in tumor detection task, we propose a hybrid feature engineering system extracting features of the tumor candidates from various perspectives and merging them in the decision stage
Intriguing Findings of Frequency Selection for Image Deblurring
Blur was naturally analyzed in the frequency domain, by estimating the latent
sharp image and the blur kernel given a blurry image. Recent progress on image
deblurring always designs end-to-end architectures and aims at learning the
difference between blurry and sharp image pairs from pixel-level, which
inevitably overlooks the importance of blur kernels. This paper reveals an
intriguing phenomenon that simply applying ReLU operation on the frequency
domain of a blur image followed by inverse Fourier transform, i.e., frequency
selection, provides faithful information about the blur pattern (e.g., the blur
direction and blur level, implicitly shows the kernel pattern). Based on this
observation, we attempt to leverage kernel-level information for image
deblurring networks by inserting Fourier transform, ReLU operation, and inverse
Fourier transform to the standard ResBlock. 1x1 convolution is further added to
let the network modulate flexible thresholds for frequency selection. We term
our newly built block as Res FFT-ReLU Block, which takes advantages of both
kernel-level and pixel-level features via learning frequency-spatial
dual-domain representations. Extensive experiments are conducted to acquire a
thorough analysis on the insights of the method. Moreover, after plugging the
proposed block into NAFNet, we can achieve 33.85 dB in PSNR on GoPro dataset.
Our method noticeably improves backbone architectures without introducing many
parameters, while maintaining low computational complexity. Code is available
at https://github.com/DeepMed-Lab/DeepRFT-AAAI2023.Comment: AAAI 202