Merge pull request #1 from trevor-m/tmorris_add_example

Add example image classification inference script and readme

Author: Pooya Davoodi

tftrt/examples/image-classification/README.md

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+# TensorFlow-TensorRT Examples
+
+This script will run inference using a few popular image classification models
+on the ImageNet validation set.
+
+You can turn on TensorFlow-TensorRT integration with the flag `--use_trt`. This
+will apply TensorRT inference optimization to speed up execution for portions of
+the model's graph where supported, and will fall back to native TensorFlow for
+layers and operations which are not supported. See
+https://devblogs.nvidia.com/tensorrt-integration-speeds-tensorflow-inference/
+for more information.
+
+When using TF-TRT, you can also control the precision with `--precision`.
+float32 is the default (`--precision fp32`) with float16 (`--precision fp16`) or
+int8 (`--precision int8`) allowing further performance improvements, at the cost
+of some accuracy. int8 mode requires a calibration step which is done
+automatically.
+
+## Models
+
+This test supports the following models for image classification:
+* MobileNet v1
+* MobileNet v2
+* NASNet - Large
+* NASNet - Mobile
+* ResNet50 v1
+* ResNet50 v2
+* VGG16
+* VGG19
+* Inception v3
+* Inception v4
+
+## Setup
+```
+# Clone [tensorflow/models](https://github.com/tensorflow/models)
+git clone https://github.com/tensorflow/models.git
+
+# Add the models directory to PYTHONPATH to install tensorflow/models.
+cd models
+export PYTHONPATH="$PYTHONPATH:$PWD"
+
+# Run the TF Slim setup.
+cd research/slim
+python setup.py install
+
+# You may also need to install the requests package
+pip install requests
+```
+Note: the PYTHONPATH environment variable will be not be saved between different
+shells. You can either repeat that step each time you work in a new shell, or
+add `export PYTHONPATH="$PYTHONPATH:/path/to/tensorflow_models"` to your .bashrc
+file (replacing /path/to/tensorflow_models with the path to your
+tensorflow/models repository).
+
+### Data
+
+The script supports only TFRecord format for data. The script
+assumes that validation TFRecords are named according to the pattern:
+`validation-*-of-00128`.
+
+You can download and process Imagenet using [this script provided by TF
+Slim](https://github.com/tensorflow/models/blob/master/research/slim/datasets/download_imagenet.sh).
+Please note that this script downloads both the training and validation sets,
+and this example only requires the validation set.
+
+## Usage
+
+`python inference.py --data_dir /imagenet_validation_data --model vgg_16 [--use_trt]`
+
+Run with `--help` to see all available options.