Contrast Limited AHE (CLAHE)

TFA already includes a global histogram equalization function (tfa.image.equalize). I’m proposing adding a python implementation of CLAHE along side that.

Relevant information

• Are you willing to contribute it (yes/no): Yes
• Are you willing to maintain it going forward? (yes/no): Yes
• Is there a relevant academic paper? (if so, where): Yes
  • S. M. Pizer, E. P. Amburn, J. D. Austin, et al.: Adaptive Histogram Equalization and Its Variations. Computer Vision, Graphics, and Image Processing 39 (1987) 355-368.
• Is there already an implementation in another framework? (if so, where): Yes
  • OpenCV
  • ImageMagick
• Was it part of tf.contrib? (if so, where): No

Which API type would this fall under (layer, metric, optimizer, etc.) image

Who will benefit with this feature? This specific feature was requested a few years ago in tensorflow main (https://github.com/tensorflow/tensorflow/issues/24181), but it looks like no one has taken it on yet. It’s especially useful for enhancing features on some medical imaging data.

Any other info. Originally asked for guidance on the tensorflow developers mailing list and was directed to open a PR here. I have a draft already and it looks like it will fit into tensorflow addons pretty well.

[isears]

Awesome! I’m going to spend a few days cleaning up my draft. I’ll plan on opening a PR sometime next week.

[bhack]

Ok we put this in the ecosystem review pipeline