Data augmentation (DA) has been widely leveraged in the realm of computer vision to alleviate the data shortage, whereas the DA in medical image analysis (MIA) faces multiple challenges. The prevalent DA approaches in MIA encompass conventional DA, synthetic DA, and automatic DA. However, the utilization of these approaches poses various challenges such as experience-driven design and intensive computation cost. Here, we propose an efficient and effective automatic DA method termed MedAugment. We propose the pixel augmentation space and spatial augmentation space and exclude the operations that can break the details and features within medical images. Besides, we propose a novel sampling strategy by sampling a limited number of operations from the two spaces. Moreover, we present a hyperparameter mapping relationship to produce a rational augmentation level and make the MedAugment fully controllable using a single hyperparameter. These revisions address the differences between natural and medical images. Extensive experimental results on four classification and three segmentation datasets demonstrate the superiority of MedAugment. We posit that the plug-and-use and training-free MedAugment holds the potential to make a valuable contribution to the medical field, particularly benefiting medical experts lacking foundational expertise in deep learning. Code is available at https://github.com/NUS-Tim/MedAugment.
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