[models] ViT add checkpoints and some rework to use pretrained ViT backbone in ViTSTR

[felixdittrich92]

This PR:

• make pretrained checkpoints available for ViT (TF and PT)
• rework patchify make it dynamic to the input shape
• rework pretrained backbone usage for ViTSTR with checkpoints
• fix issue with bicubic scale and onnxruntime (use bilinear : minor cost on quality and speed up)

All added checkpoints >98% acc

Any feedback is welcome

[felixdittrich92]

@frgfm but the good on is i have learned a lesson in this PR. If we build TF models each layer should have a name otherwise we are lost in space if we iter trough the weights to find the problem 😅

[codecov]

Codecov Report

Merging #1072 (7365d49) into main (e538cc2) will decrease coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1072      +/-   ##
==========================================
- Coverage   95.26%   95.21%   -0.06%     
==========================================
  Files         145      142       -3     
  Lines        6046     6018      -28     
==========================================
- Hits         5760     5730      -30     
- Misses        286      288       +2     

Flag	Coverage Δ
unittests	95.21% <100.00%> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
doctr/models/recognition/vitstr/pytorch.py	97.46% <ø> (ø)
doctr/models/classification/vit/pytorch.py	100.00% <100.00%> (ø)
doctr/models/classification/vit/tensorflow.py	100.00% <100.00%> (ø)
doctr/models/modules/vision_transformer/pytorch.py	97.72% <100.00%> (-2.28%)	⬇️
...tr/models/modules/vision_transformer/tensorflow.py	97.72% <100.00%> (-2.28%)	⬇️
doctr/models/recognition/vitstr/tensorflow.py	97.56% <100.00%> (ø)
doctr/transforms/functional/base.py	95.65% <0.00%> (ø)
doctr/utils/__init__.py
... and 2 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[frgfm]

Thanks Felix!
Perhaps we should specify the change in perf in the documentation or somewhere? It's gonna become hard to track those changes otherwise

[felixdittrich92]

Yep will add
Patches: (H, W) -> (H / 8, W / 8)
to the docstrings

[odulcy-mindee]

LGTM ! 🚀