A demo notebook for the Table Transformer can be found here.
It turns out padding of images is quite important for detection. An interesting Github thread with replies from the authors can be found here.

TableTransformerConfig
[[autodoc]] TableTransformerConfig
TableTransformerModel
[[autodoc]] TableTransformerModel
    - forward
TableTransformerForObjectDetection
[[autodoc]] TableTransformerForObjectDetection
    - forward