# TensorFlow Object Detection API
[![TensorFlow 2.2](https://img.shields.io/badge/TensorFlow-2.2-FF6F00?logo=tensorflow)](https://github.com/tensorflow/tensorflow/releases/tag/v2.2.0)
[![TensorFlow 1.15](https://img.shields.io/badge/TensorFlow-1.15-FF6F00?logo=tensorflow)](https://github.com/tensorflow/tensorflow/releases/tag/v1.15.0)
[![Python 3.6](https://img.shields.io/badge/Python-3.6-3776AB)](https://www.python.org/downloads/release/python-360/)

Creating accurate machine learning models capable of localizing and identifying
multiple objects in a single image remains a core challenge in computer vision.
The TensorFlow Object Detection API is an open source framework built on top of
TensorFlow that makes it easy to construct, train and deploy object detection
models. At Google we’ve certainly found this codebase to be useful for our
computer vision needs, and we hope that you will as well. <p align="center">
<img src="g3doc/img/kites_detections_output.jpg" width=676 height=450> </p>
Contributions to the codebase are welcome and we would love to hear back from
you if you find this API useful. Finally if you use the TensorFlow Object
Detection API for a research publication, please consider citing:

```
"Speed/accuracy trade-offs for modern convolutional object detectors."
Huang J, Rathod V, Sun C, Zhu M, Korattikara A, Fathi A, Fischer I, Wojna Z,
Song Y, Guadarrama S, Murphy K, CVPR 2017
```

\[[link](https://arxiv.org/abs/1611.10012)\]\[[bibtex](https://scholar.googleusercontent.com/scholar.bib?q=info:l291WsrB-hQJ:scholar.google.com/&output=citation&scisig=AAGBfm0AAAAAWUIIlnPZ_L9jxvPwcC49kDlELtaeIyU-&scisf=4&ct=citation&cd=-1&hl=en&scfhb=1)\]

<p align="center">
  <img src="g3doc/img/tf-od-api-logo.png" width=140 height=195>
</p>

## Support for TensorFlow 2 and 1
The TensorFlow Object Detection API supports both TensorFlow 2 (TF2) and
TensorFlow 1 (TF1). A majority of the modules in the library are both TF1 and
TF2 compatible. In cases where they are not, we provide two versions.

Although we will continue to maintain the TF1 models and provide support, we
encourage users to try the Object Detection API with TF2 for the following
reasons:

* We provide new architectures supported in TF2 only and we will continue to
  develop in TF2 going forward.

* The popular models we ported from TF1 to TF2 achieve the same performance.

* A single training and evaluation binary now supports both GPU and TPU
  distribution strategies making it possible to train models with synchronous
  SGD by default.

* Eager execution with new binaries makes debugging easy!

Finally, if are an existing user of the Object Detection API we have retained
the same config language you are familiar with and ensured that the
TF2 training/eval binary takes the same arguments as our TF1 binaries.

Note: The models we provide in [TF2 Zoo](g3doc/tf2_detection_zoo.md) and
[TF1 Zoo](g3doc/tf1_detection_zoo.md) are specific to the TensorFlow major
version and are not interoperable.

Please select one of the links below for TensorFlow version-specific
documentation of the Object Detection API:

<!-- mdlint off(WHITESPACE_LINE_LENGTH) -->
### Tensorflow 2.x
  *   <a href='g3doc/tf2.md'>
        Object Detection API TensorFlow 2</a><br>
  *   <a href='g3doc/tf2_detection_zoo.md'>
        TensorFlow 2 Model Zoo</a><br>

### Tensorflow 1.x
  *   <a href='g3doc/tf1.md'>
        Object Detection API TensorFlow 1</a><br>
  *   <a href='g3doc/tf1_detection_zoo.md'>
        TensorFlow 1 Model Zoo</a><br>
<!-- mdlint on -->

## Whats New

### TensorFlow 2 Support

We are happy to announce that the TF OD API officially supports TF2! Our release
includes:

* New binaries for train/eval/export that are designed to run in eager mode.
* A suite of TF2 compatible (Keras-based) models; this includes migrations of
  our most popular TF1.x models (e.g., SSD with MobileNet, RetinaNet,
  Faster R-CNN, Mask R-CNN), as well as a few new architectures for which we
  will only maintain TF2 implementations:

    1. CenterNet - a simple and effective anchor-free architecture based on
       the recent [Objects as Points](https://arxiv.org/abs/1904.07850) paper by
       Zhou et al.
    2. [EfficientDet](https://arxiv.org/abs/1911.09070) - a recent family of
       SOTA models discovered with the help of Neural Architecture Search.

* COCO pre-trained weights for all of the models provided as TF2 style
  object-based checkpoints.
* Access to [Distribution Strategies](https://www.tensorflow.org/guide/distributed_training)
  for distributed training --- our model are designed to be trainable using sync
  multi-GPU and TPU platforms.
* Colabs demo’ing eager mode training and inference.

See our release blogpost [here](https://blog.tensorflow.org/2020/07/tensorflow-2-meets-object-detection-api.html).
If you are an existing user of the TF OD API using TF 1.x, don’t worry, we’ve
got you covered.

**Thanks to contributors**: Akhil Chinnakotla, Allen Lavoie, Anirudh Vegesana,
Anjali Sridhar, Austin Myers, Dan Kondratyuk, David Ross, Derek Chow, Jaeyoun
Kim, Jing Li, Jonathan Huang, Jordi Pont-Tuset, Karmel Allison, Kathy Ruan,
Kaushik Shivakumar, Lu He, Mingxing Tan, Pengchong Jin, Ronny Votel, Sara Beery,
Sergi Caelles Prat, Shan Yang, Sudheendra Vijayanarasimhan, Tina Tian, Tomer
Kaftan, Vighnesh Birodkar, Vishnu Banna, Vivek Rathod, Yanhui Liang, Yiming Shi,
Yixin Shi, Yu-hui Chen, Zhichao Lu.

### MobileDet GPU

We have released SSDLite with MobileDet GPU backbone, which achieves 17% mAP
higher than the MobileNetV2 SSDLite (27.5 mAP vs 23.5 mAP) on a NVIDIA Jetson
Xavier at comparable latency (3.2ms vs 3.3ms).

Along with the model definition, we are also releasing model checkpoints trained
on the COCO dataset.

<b>Thanks to contributors</b>: Yongzhe Wang, Bo Chen, Hanxiao Liu, Le An
(NVIDIA), Yu-Te Cheng (NVIDIA), Oliver Knieps (NVIDIA), and Josh Park (NVIDIA).

### Context R-CNN

We have released [Context R-CNN](https://arxiv.org/abs/1912.03538), a model that
uses attention to incorporate contextual information images (e.g. from
temporally nearby frames taken by a static camera) in order to improve accuracy.
Importantly, these contextual images need not be labeled.

*   When applied to a challenging wildlife detection dataset
    ([Snapshot Serengeti](http://lila.science/datasets/snapshot-serengeti)),
    Context R-CNN with context from up to a month of images outperforms a
    single-frame baseline by 17.9% mAP, and outperforms S3D (a 3d convolution
    based baseline) by 11.2% mAP.
*   Context R-CNN leverages temporal context from the unlabeled frames of a
    novel camera deployment to improve performance at that camera, boosting
    model generalizeability.

Read about Context R-CNN on the Google AI blog
[here](https://ai.googleblog.com/2020/06/leveraging-temporal-context-for-object.html).

We have provided code for generating data with associated context
[here](g3doc/context_rcnn.md), and a sample config for a Context R-CNN model
[here](samples/configs/context_rcnn_resnet101_snapshot_serengeti_sync.config).

Snapshot Serengeti-trained Faster R-CNN and Context R-CNN models can be found in
the
[model zoo](https://github.com/tensorflow/models/blob/master/research/object_detection/g3doc/tf1_detection_zoo.md#snapshot-serengeti-camera-trap-trained-models).

A colab demonstrating Context R-CNN is provided
[here](colab_tutorials/context_rcnn_tutorial.ipynb).

<b>Thanks to contributors</b>: Sara Beery, Jonathan Huang, Guanhang Wu, Vivek
Rathod, Ronny Votel, Zhichao Lu, David Ross, Pietro Perona, Tanya Birch, and the
Wildlife Insights AI Team.

## Release Notes
See [notes](g3doc/release_notes.md) for all past releases.

## Getting Help

To get help with issues you may encounter using the TensorFlow Object Detection
API, create a new question on [StackOverflow](https://stackoverflow.com/) with
the tags "tensorflow" and "object-detection".

Please report bugs (actually broken code, not usage questions) to the
tensorflow/models GitHub
[issue tracker](https://github.com/tensorflow/models/issues), prefixing the
issue name with "object_detection".

Please check the [FAQ](g3doc/faq.md) for frequently asked questions before
reporting an issue.

## Maintainers

* Jonathan Huang ([@GitHub jch1](https://github.com/jch1))
* Vivek Rathod ([@GitHub tombstone](https://github.com/tombstone))
* Vighnesh Birodkar ([@GitHub vighneshbirodkar](https://github.com/vighneshbirodkar))
* Austin Myers ([@GitHub austin-myers](https://github.com/austin-myers))
* Zhichao Lu ([@GitHub pkulzc](https://github.com/pkulzc))
* Ronny Votel ([@GitHub ronnyvotel](https://github.com/ronnyvotel))
* Yu-hui Chen ([@GitHub yuhuichen1015](https://github.com/yuhuichen1015))
* Derek Chow  ([@GitHub derekjchow](https://github.com/derekjchow))
