TensorFlow + Golang + Docker = all for image recognition Docker Meetup at Amazon India Bangalore – Sangam Biradar

@here is the biggest event at Amazon India bangalore and its honour to speak at this event front of 400+ attendees

Introduction to TensorFlow

Tensors, in general, are simply arrays of numbers, or functions, that transform according to certain rules under a change of coordinates. TensorFlow is an open source software library for doing graph-based computations quickly. It does this by utilizing the GPU(Graphics Processing Unit), and also making it easy to distribute the work across multiple GPUs and computers.

Nodes in the graph represent mathematical operations, while the graph edges represent the multidimensional data arrays (tensors) communicated between them. This model is used for learning vector representations of words, called word embeddings. One of the tasks at which it excels is implementing and training deep neural networks.

TensorFlow with Golang

Tensor flow is not a Machine Learning specific library, instead, is a general purpose computation library that represents computations with graphs. Its core is implemented in C++ and there are also bindings for different languages, including Go.

In the last few years the field of machine learning has made tremendous progress on addressing the difficult problem of image recognition.

One of the challenges with machine learning is figuring out how to deploy trained models into production environments. After training your model, you can “freeze” it and export it to be used in a production environment


For some common-use-cases we’re beginning to see organizations sharing their trained models, you can find some in the TensorFlow Models repo https://github.com/tensorflow/models.

we’ll use one of them, called Inception to recognize an image. https://github.com/tensorflow/models/tree/master/research/inception/inception

Tensor flow trained model 

We’ll build a small command line application that takes URL to an image as input and outputs labels in order.

First of all we need to install TensorFlow, and here Docker can be really helpful, because installation of Tensorflowmay be complicated. There is a Docker image with Tensorflow, but without Go, so I found an image with Tensorflowplus Go to reduce  Dockerfile.


Download Inception data: http://download.tensorflow.org/models/inception5h.zip

Let’s start with simple main.go file to test if our Dockerfile works.

package main
 func main() {
     if len(os.Args) < 2 
log.Fatalf("usage: imgrecognition ")
     fmt.Printf("url: %s\n", os.Args[1])
docker build -t imgrecognition .
docker run imgrecognition https://www.iaspaper.net/wp-content/uploads/2017/10/Rabbit-Essay.jpg

Let’s get our image from the provided URL:

// Get image from URL
 response, e := http.Get(os.Args[1])
 if e != nil {
     log.Fatalf("unable to get image from url: %v", e)
 defer response.Body.Close()

Now we need to load our model. Model contains graph and labels in 2 files:

const (
     graphFile = "/model/imagenet_comp_graph_label_strings.txt"
     labelsFile = "/model/imagenet_comp_graph_label_strings.txt"
 graph, labels, err := loadModel()
 if err != nil {
     log.Fatalf("unable to load model: %v", err)
 func loadModel() (*tf.Graph, []string, error) {
     // Load inception model
     model, err := ioutil.ReadFile(graphFile)
     if err != nil {
         return nil, nil, err
     graph := tf.NewGraph()
     if err := graph.Import(model, ""); err != nil {
         return nil, nil, err
 // Load labels labelsFile, err := os.Open() if err != nil
return nil, nil, err 
 defer labelsFile.Close() scanner := bufio.NewScanner(labelsFile) var labels []string for scanner.Scan() 
{     labels = append(labels, scanner.Text()) 
 return graph, labels, scanner.Err()

Here finally we start using tensorflow Go package. To be able to work with our image we need to normalize it, because Inception model expects it to be in a certain format, it uses images from ImageNet, and they are 224×224. But that’s a bit tricky. Let’s see:

  • NewTensor converts from a Go value to a Tensor
  • Build a graph of our image
  • Init a session, because all Graph operations in Tensorflow are done with sessions.
  • Run the session to normalize image, using input and output.
  • normalized[0] contains normalized Tensor.
  • In makeTransformImageGraph we define the rules of normalization.
func normalizeImage(body io.ReadCloser) (*tensorflow.Tensor, error) {
     var buf bytes.Buffer
     io.Copy(&buf, body)
 tensor, err := tensorflow.NewTensor(buf.String()) if err != nil {     return nil, err } graph, input, output, err := getNormalizedGraph() if err != nil {     return nil, err } session, err := tensorflow.NewSession(graph, nil) if err != nil {     return nil, err } normalized, err := session.Run(     map[tensorflow.Output]*tensorflow.Tensor{         input: tensor,     },     []tensorflow.Output{         output,     },     nil) if err != nil {     return nil, err } return normalized[0], nil
 // Creates a graph to decode, rezise and normalize an image
 func getNormalizedGraph() (graph *tensorflow.Graph, input, output tensorflow.Output, err error) {
     s := op.NewScope()
     input = op.Placeholder(s, tensorflow.String)
     // 3 return RGB image
     decode := op.DecodeJpeg(s, input, op.DecodeJpegChannels(3))
 // Sub: returns x - y element-wise output = op.Sub(s,     // make it 224x224: inception specific     op.ResizeBilinear(s,         // inserts a dimension of 1 into a tensor's shape.         op.ExpandDims(s,             // cast image to float type             op.Cast(s, decode, tensorflow.Float),             op.Const(s.SubScope("make_batch"), int32(0))),         op.Const(s.SubScope("size"), []int32{224, 224})),     // mean = 117: inception specific     op.Const(s.SubScope("mean"), float32(117))) graph, err = s.Finalize() return graph, input, output, err

Fnally we need to init one more session on our initial model graph to find matches.

// Create a session for inference over modelGraph.
 session, err := tf.NewSession(modelGraph, nil)
 if err != nil {
     log.Fatalf("could not init session: %v", err)
 defer session.Close()
 output, err := session.Run(
         modelGraph.Operation("input").Output(0): tensor,
 if err != nil {
     log.Fatalf("could not run inference: %v", err)

It will return list of probabilities for each label. What we need now is to loop over all probabilities and find label in labelsslice. And print top 5.

res := getTopFiveLabels(labels, output[0].Value().([][]float32)[0])
 for _, l := range res {
     fmt.Printf("label: %s, probability: %.2f%%\n", l.Label, l.Probability*100)
 func getTopFiveLabels(labels []string, probabilities []float32) []Label {
     var resultLabels []Label
     for i, p := range probabilities {
         if i >= len(labels) {
         resultLabels = append(resultLabels, Label{Label: labels[i], Probability: p})
 sort.Sort(Labels(resultLabels)) return resultLabels[:5]


Also let’s skip those warnings:

os.Setenv("TF_CPP_MIN_LOG_LEVEL", "2")

Here we worked with pre-trained model, let’s try this program with something unusual, like … Gopher.

docker run imgrecognition https://i.pinimg.com/736x/12/5c/e0/125ce0baff3271761ca61843eccf7985.jpg

Mouse?? no! But it’s possible to train our models from Go in TensorFlow, and I will definitely do a video about it.

demo –

node1 root@ ~
 $ git clone https://github.com/sangam14/Tenserflow-golang-docker-image-recongnition
 Cloning into 'Tenserflow-golang-docker-image-recongnition'…
 remote: Enumerating objects: 15, done.
 remote: Counting objects: 100% (15/15), done.
 remote: Compressing objects: 100% (10/10), done.
 remote: Total 15 (delta 3), reused 12 (delta 3), pack-reused 0
 Unpacking objects: 100% (15/15), done.
 node1 root@ ~
 $ ls
 node1 root@ ~
 $ cd Tenserflow-golang-docker-image-recongnition/
 node1 root@ ~/Tenserflow-golang-docker-image-recongnition
 $ ls
 Dockerfile  README.md   main.go
 node1 root@ ~/Tenserflow-golang-docker-image-recongnition
 node1 root@ ~/Tenserflow-golang-docker-image-recongnition
 $ ls
 Dockerfile  README.md   main.go
 node1 root@ ~/Tenserflow-golang-docker-image-recongnition
 $ docker build -t imgrecognition .
 Sending build context to Docker daemon  86.53kB
 Step 1/6 : FROM ctava/tfcgo
 latest: Pulling from ctava/tfcgo
 d3938036b19c: Pull complete
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 Digest: sha256:37f41a3a3f307d459a9c9c24340f2442132eb338b9a9f7285f21be7406311623
 Status: Downloaded newer image for ctava/tfcgo:latest
  ---> 0dd6682b1573
 Step 2/6 : RUN mkdir -p /model &&   curl -o /model/inception5h.zip -s "http://download.tensorflow.org/models/inception5h.zip" &&   unzip /model/inception5h.zip -d /model
  ---> Running in fee6bfa3acda
 Archive:  /model/inception5h.zip
   inflating: /model/imagenet_comp_graph_label_strings.txt
   inflating: /model/tensorflow_inception_graph.pb
   inflating: /model/LICENSE
 Removing intermediate container fee6bfa3acda
  ---> a6c30a8b1f0b
 Step 3/6 : WORKDIR /go/src/imgrecognition
  ---> Running in a340d3cdbefc
 Removing intermediate container a340d3cdbefc
  ---> 092ec689f5e2
 Step 4/6 : COPY . .
  ---> 7404eb0d2015
 Step 5/6 : RUN go build
  ---> Running in 9693fb540f7d
 Removing intermediate container 9693fb540f7d
  ---> b42d3e7b5836
 Step 6/6 : ENTRYPOINT [ "/go/src/imgrecognition/imgrecognition" ]
  ---> Running in 9dc911f7b6f1
 Removing intermediate container 9dc911f7b6f1
  ---> 45b0bb08fb9a
 Successfully built 45b0bb08fb9a
 Successfully tagged imgrecognition:latest
 node1 root@ ~/Tenserflow-golang-docker-image-recongnition
 $ docker run imgrecognition https://i.pinimg.com/736x/12/5c/e0/125ce0baff3271761ca61843eccf7985.jpg
 url: https://i.pinimg.com/736x/12/5c/e0/125ce0baff3271761ca61843eccf7985.jpg
 label: mouse, probability: 14.93%
 label: pick, probability: 10.40%
 label: wall clock, probability: 7.56%
 label: shield, probability: 5.54%
 label: hook, probability: 4.72%

after event scenes:

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thanks for stickers

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