Synthetic dual image generation for reduction of labeling efforts in semantic segmentation of micrographs with a customized metric function
This provides a user-friendly solution for material scientists and researchers needing semantic segmentation with limited labeled micrograph data, though it is incremental as it adapts existing generative methods to a specific domain.
The paper tackles the problem of training robust semantic segmentation models for material analysis when perfect masks are scarce and data is limited by generating synthetic microstructural images and masks using a VQ-VAE and PixelCNN workflow. The result is a reduction in labeling efforts and sample preparation times, with models trained on synthetic data achieving competitive performance on non-synthetic images.
Training of semantic segmentation models for material analysis requires micrographs and their corresponding masks. It is quite unlikely that perfect masks will be drawn, especially at the edges of objects, and sometimes the amount of data that can be obtained is small, since only a few samples are available. These aspects make it very problematic to train a robust model. We demonstrate a workflow for the improvement of semantic segmentation models of micrographs through the generation of synthetic microstructural images in conjunction with masks. The workflow only requires joining a few micrographs with their respective masks to create the input for a Vector Quantised-Variational AutoEncoder model that includes an embedding space, which is trained such that a generative model (PixelCNN) learns the distribution of each input, transformed into discrete codes, and can be used to sample new codes. The latter will eventually be decoded by VQ-VAE to generate images alongside corresponding masks for semantic segmentation. To evaluate the synthetic data, we have trained U-Net models with different amounts of these synthetic data in conjunction with real data. These models were then evaluated using non-synthetic images only. Additionally, we introduce a customized metric derived from the mean Intersection over Union (mIoU). The proposed metric prevents a few falsely predicted pixels from greatly reducing the value of the mIoU. We have achieved a reduction in sample preparation and acquisition times, as well as the efforts, needed for image processing and labeling tasks, are less when it comes to training semantic segmentation model. The approach could be generalized to various types of image data such that it serves as a user-friendly solution for training models with a small number of real images.