String output model demo

Overview

This demo demonstrates example deployment of a model with output precision ov::element::string. The output text is serialized into corresponding fields in gRPC proto/REST body. This allows the client to consume the text directly and avoid the process of label mapping or detokenization.

Download and prepare MobileNet model using from TensorFlow

The script below is downloading a public MobileNet model trained on the ImageNet data. The original model accepts on input the image array in the range of 0-1 and returns probabilities for all the trained classes. We are adding to the model preprocessing function changing the input data range to 0-255 and also postprocessing function which is retrieving the most likely label name as a string. This is a very handy functionality because it allows us to export the model with the included pre/post processing functions as the model layers. The client just receives the string data with the label name for the classified image.

git clone https://github.com/openvinotoolkit/model_server.git
cd model_server/demos/image_classification_with_string_output
pip install -r requirements.txt
python3 download_model.py
rm model/1/fingerprint.pb

tree model
model
└── 1
    ├── assets
    ├── saved_model.pb
    └── variables
        ├── variables.data-00000-of-00001
        └── variables.index

Start the OVMS container:

docker run -d -u $(id -u):$(id -g) -v $(pwd):/workspace -p 8000:8000 openvino/model_server:latest \
--model_path /workspace/model --model_name mobile_net --rest_port 8000

Send request

Use example client to send requests containing images via KServ REST API:

python3 image_classification_with_string_output.py --http_port 8000

Request may be sent also using other APIs (KServ GRPC, TFS). In this sections you can find short code samples how to do this:

• TensorFlow Serving API

• KServe API

Expected output

Start processing:
        Model name: mobile_net
../common/static/images/airliner.jpeg classified  as airliner
Iteration 0; Processing time: 31.09 ms; speed 32.16 fps

../common/static/images/arctic-fox.jpeg classified  as Arctic fox
Iteration 0; Processing time: 5.27 ms; speed 189.75 fps

../common/static/images/bee.jpeg classified  as bee
Iteration 0; Processing time: 3.02 ms; speed 331.46 fps

../common/static/images/golden_retriever.jpeg classified  as clumber
Iteration 0; Processing time: 3.12 ms; speed 320.82 fps

../common/static/images/gorilla.jpeg classified  as gorilla
Iteration 0; Processing time: 3.04 ms; speed 329.06 fps

../common/static/images/magnetic_compass.jpeg classified  as magnetic compass
Iteration 0; Processing time: 3.10 ms; speed 323.00 fps

../common/static/images/peacock.jpeg classified  as peacock
Iteration 0; Processing time: 3.24 ms; speed 308.17 fps

../common/static/images/pelican.jpeg classified  as pelican
Iteration 0; Processing time: 3.17 ms; speed 315.36 fps

../common/static/images/snail.jpeg classified  as snail
Iteration 0; Processing time: 3.06 ms; speed 327.33 fps

../common/static/images/zebra.jpeg classified  as zebra
Iteration 0; Processing time: 4.19 ms; speed 238.72 fps