Week of 2026-06-08

pix2pix troubleshooting

syn7T

Mary reran the pix2pix model on a more tightly constrained dataset, following the preprocessing changes made after the initial run. Visual quality assessment is ongoing, and a traceability gap in the output pipeline turned up that needs fixing.

The constrained dataset uses a higher slice-inclusion threshold and 512×512 with zero padding (see the previous entry). Checkpoints are at /home/lenkm/syn7T/pytorch-CycleGAN-and-pix2pix/checkpoints/ on LRI-111261, and the output images sit in the web/ subdirectory of each run folder.

It’s hard to tell from inspection alone how much the constrained dataset improved synthesis quality relative to the initial run. We’ll need formal quantitative evaluation (iBEAT v2.0 Dice/IoU) to resolve it.

The one issue that surfaced during review: some paired 3T and 7T images didn’t appear to represent the same slice, suggesting possible misalignment or pairing errors in the dataset or preprocessing. The current pix2pix implementation doesn’t save outputs with a reference back to their source filenames, so there’s no way to trace a synthesized output back to its input slices. The fix is to modify the pix2pix code to save source filename references alongside generated outputs, which would let us tie quality assessment to specific input pairs, spot systematic misalignment patterns, and track down artifact sources more easily.

Next steps:

• Mary to modify pix2pix to save outputs with source-filename traceability
• Review outputs on LRI-111261 at the path above once traceability is in place
• Formally evaluate synthesis quality with iBEAT v2.0 (Dice/IoU) once a clean traceable run is available
• Revisit slice pairing in preprocessing to confirm 3T/7T correspondence