Check which image ops are compatible with tf.data.Dataset

[facaiy]

Follow up #243.

Here is a check list:

• dense_image_warp
• sparse_image_warp
• interpolate_bilinear
• euclidean_distance_transform
• adjust_hsv_in_yiq
• random_hsv_in_yiq
• mean_filter2d
• median_filter2d
• angles_to_projective_transforms
• matrices_to_flat_transforms
• rotate
• transform

Like what we did in #330, feel free to open a pull request for each op:

1. Add test for unknown rank image tensor.
2. Fix it if possible. Otherwise, please notice users that the op is not compatible with unknown rank tensor (shape=None) in its document.

[satishjasthi]

Hello,
Can anyone help me how to test whether a tfa op is compatible with tf.Dataset.
I would like to check for

• dense_image_warp
• interpolate_bilinear
  My question might sound silly, I'm a newbie please help me.

[seanpmorgan]

Hi @satishjasthi welcome to addons! So this colab notebook shows what the issue was (has since been fixed for that op):
https://colab.research.google.com/drive/1ZDhnGrorvSf04wzS-0utztZ6Nnzusvl7

Basically, if an image op can't be used in a tf.dataset mapping it's likely because we're not handling an unknown shape correctly. tf.dataset runs as a subgraph so the dynamic shape is not known until the graph is ran.

A good test to see if it's compatible can be see in previous pull requests that adressed this:
https://github.com/tensorflow/addons/pull/343/files#diff-7137321db62bba0af8193f6f6213fd46R243

Yan added an image util which can be used to infer shape:
https://github.com/tensorflow/addons/blob/master/tensorflow_addons/image/utils.py#L29

Let us know if you run into any issues, and thanks for the help!