cs.CVMar 2, 2026

AutoFFS: Adversarial Deformations for Facial Feminization Surgery Planning

Authors: Paul Friedrich, Florentin Bieder, Florian M. Thieringer, Philippe C. Cattin

Organizations: Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland · Department of Oral and Cranio-Maxillofacial Surgery, University Hospital Basel, Basel, Switzerland

Abstract

Facial feminization surgery (FFS) is a key component of gender affirmation for transgender and gender diverse patients, aiming to reshape craniofacial structures toward a female morphology. Current surgical planning procedures largely rely on subjective clinical assessment, lacking quantitative and reproducible anatomical guidance. We therefore propose AutoFFS, a novel data-driven framework that generates counterfactual skull morphologies through adversarial free-form deformations. Our method performs a deformation-based targeted adversarial attack on an ensemble of pre-trained binary sex classifiers that learned sexual dimorphism, effectively transforming individual skull shapes toward the target sex. The generated counterfactual skull morphologies provide a quantitative foundation for preoperative planning in FFS, driving advances in this largely overlooked patient group. We validate our approach through classifier-based evaluation, propose Morphological Fréchet Distance (MFD) and Morphological Kernel Distance (MKD) to evaluate distributional alignment of generated and real populations, and perform a human perceptual study, confirming that the generated morphologies exhibit target sex characteristics.

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