Add Mask-RCNN model

[innat]

Short Description

A two stage object detection model, strongly well-known for its detection and instance-wise simultaneous output.

Papers https://arxiv.org/abs/1703.06870

Publish date: 2017 Cited by 20059 (until now)

Existing Implementations

A very popular and well-know keras (tf 1.5x) implementation.

• https://github.com/matterport/Mask_RCNN (over 22K + star, 11K+ fork).

Other Information

• tensorflow-model-zoo: https://github.com/tensorflow/models/tree/master/official/vision#Instance-Segmentation-Baselines

[MrinalTyagi]

Any decision to implement this? Would love to contribute the model.

[innat]

This needs to be first, I think. https://github.com/keras-team/keras-cv/issues/669