alaska2

https://www.kaggle.com/c/alaska2-image-steganalysis/overview

main ideas

stacking of several models (b2, b3, b7)
focall loss
gradient accumulation
label smoothing
reduce lr on plateau
balanced class sampler catalyst
augmentations with flips (horizntal, vertical)

results:

private LB: 107/1115 place top 10%, bronze medal