Puzzle-Cam: Improved Localization Via Matching Partial And Full Features

Weakly-supervised semantic segmentation (WSSS) is introduced to narrow the gap for semantic segmentation performance from pixel-level supervision to image-level surpervision. Most advanced approaches are based on class activation maps (CAMs) to generate pseudo-labels to train the segmentation network. The main limitation of WSSS is that the process of generating pseudo-labels from CAMs which use an image classifier is mainly focused on the most discriminative parts of the objects. To address this issue, we propose Puzzle-CAM, a process minimizes the differences between the features from separate patches and the whole image. Our method consists of a puzzle module (PM) and two regularization terms to discover the most integrated region of in an object. Without requiring extra parameters, Puzzle-CAM can activate the overall region of an object using image-level supervision. In experiments, Puzzle-CAM outperformed previous state-of-the-art methods using the same labels for supervision on the PASCAL VOC 2012 test dataset.