Tools to convert ONNX files (NCHW) to TensorFlow format (NHWC)

• Concat

  • Improved Concat conversion stability.
  • In 4D, the maximum number of attempts introduced by the new search logic is roughly bounded as:

    4 * P^N
    

  • 4 is the number of candidate axes (0–3).
  • P is the number of permutation candidates per input.
  • N is the number of input tensors.

  Permutation count P:

  • Full search: P = 24 (all 4D permutations).
  • If 24^N exceeds the guard threshold (20,000), the search switches to a limited set, so P = 3.

  Worst-case attempts:

  • N=2: 4 * 24^2 = 2,304
  • N=3: 4 * 24^3 = 55,296
  • N=4: 24^4 exceeds the threshold, so limited mode: 4 * 3^4 = 324

These are hard upper bounds; in practice the actual attempts are typically much fewer because shape-incompatible candidates are pruned before tf.concat, and the search stops early once the ONNX output shape matches.

• e2pose <img width="1556" height="478" alt="image" src="https://github.com/user-attachments/assets/2b92266c-bbc5-4178-b56f-2542f8386669" />

What's Changed

• Improved Concat conversion stability by @PINTO0309 in https://github.com/PINTO0309/onnx2tf/pull/821

Full Changelog: https://github.com/PINTO0309/onnx2tf/compare/1.29.16...1.29.17