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Resolving the PatchGAN Paradox

A four-model discriminator ablation of conditional GANs for MRI tumour segmentation on BraTS 2020, linking checkerboard artefacts to kernel and stride.

Stack
PyTorch · cGAN · U-Net · BraTS 2020
Key figure
0.958 — SSIM
DG Labs

PatchGAN Paradox

0.958SSIM

PyTorch · cGAN · U-Net · BraTS 2020

01

The problem

Conditional GANs segment brain tumours from MRI well, but their outputs carry checkerboard artefacts — and it is not obvious which part of the discriminator design is responsible.

02

The approach

Ran a four-model discriminator ablation of cGANs with a U-Net generator on BraTS 2020, varying the discriminator's kernel and stride, and traced the artefacts back to those choices.

03

The outcome

A 4×4, stride-2 PatchGAN scored best: PSNR 25.96 dB and SSIM 0.958. The artefacts were linked directly to kernel/stride configuration.

Of note

  • ✦ Four-model discriminator ablation
  • ✦ Checkerboard artefacts linked to kernel/stride
  • ✦ Best: 4×4 stride-2 PatchGAN — PSNR 25.96 dB
  • ✦ SSIM 0.958 on BraTS 2020