Detecting Labels

Label Detection detects broad sets of categories within an image, which range from modes of transportation to animals.

Detecting Labels in a local image

Protocol

Refer to the images:annotate API endpoint for complete details.

To perform Label Detection, make a POST request and provide the appropriate request body:

POST https://vision.googleapis.com/v1/images:annotate?key=YOUR_API_KEY
{
  "requests": [
    {
      "image": {
        "content": "/9j/7QBEUGhvdG9zaG9...base64-encoded-image-content...fXNWzvDEeYxxxzj/Coa6Bax//Z"
      },
      "features": [
        {
          "type": "LABEL_DETECTION"
        }
      ]
    }
  ]
}

See the AnnotateImageRequest reference documentation for more information on configuring the request body.

C#

Before trying this sample, follow the C# setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API C# API reference documentation .

// Load an image from a local file.
var image = Image.FromFile(filePath);
var client = ImageAnnotatorClient.Create();
var response = client.DetectLabels(image);
foreach (var annotation in response)
{
    if (annotation.Description != null)
        Console.WriteLine(annotation.Description);
}

Go

Before trying this sample, follow the Go setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API Go API reference documentation .

// detectLabels gets labels from the Vision API for an image at the given file path.
func detectLabels(w io.Writer, file string) error {
	ctx := context.Background()

	client, err := vision.NewImageAnnotatorClient(ctx)
	if err != nil {
		return err
	}

	f, err := os.Open(file)
	if err != nil {
		return err
	}
	defer f.Close()

	image, err := vision.NewImageFromReader(f)
	if err != nil {
		return err
	}
	annotations, err := client.DetectLabels(ctx, image, nil, 10)
	if err != nil {
		return err
	}

	if len(annotations) == 0 {
		fmt.Fprintln(w, "No labels found.")
	} else {
		fmt.Fprintln(w, "Labels:")
		for _, annotation := range annotations {
			fmt.Fprintln(w, annotation.Description)
		}
	}

	return nil
}

Java

Before trying this sample, follow the Java setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API Java API reference documentation .

public static void detectLabels(String filePath, PrintStream out) throws Exception, IOException {
  List<AnnotateImageRequest> requests = new ArrayList<>();

  ByteString imgBytes = ByteString.readFrom(new FileInputStream(filePath));

  Image img = Image.newBuilder().setContent(imgBytes).build();
  Feature feat = Feature.newBuilder().setType(Type.LABEL_DETECTION).build();
  AnnotateImageRequest request =
      AnnotateImageRequest.newBuilder().addFeatures(feat).setImage(img).build();
  requests.add(request);

  try (ImageAnnotatorClient client = ImageAnnotatorClient.create()) {
    BatchAnnotateImagesResponse response = client.batchAnnotateImages(requests);
    List<AnnotateImageResponse> responses = response.getResponsesList();

    for (AnnotateImageResponse res : responses) {
      if (res.hasError()) {
        out.printf("Error: %s\n", res.getError().getMessage());
        return;
      }

      // For full list of available annotations, see http://g.co/cloud/vision/docs
      for (EntityAnnotation annotation : res.getLabelAnnotationsList()) {
        annotation.getAllFields().forEach((k, v) -> out.printf("%s : %s\n", k, v.toString()));
      }
    }
  }
}

Node.js

Before trying this sample, follow the Node.js setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API Node.js API reference documentation .

// Imports the Google Cloud client library
const vision = require('@google-cloud/vision');

// Creates a client
const client = new vision.ImageAnnotatorClient();

/**
 * TODO(developer): Uncomment the following line before running the sample.
 */
// const fileName = 'Local image file, e.g. /path/to/image.png';

// Performs label detection on the local file
client
  .labelDetection(fileName)
  .then(results => {
    const labels = results[0].labelAnnotations;
    console.log('Labels:');
    labels.forEach(label => console.log(label.description));
  })
  .catch(err => {
    console.error('ERROR:', err);
  });

PHP

Before trying this sample, follow the PHP setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API PHP API reference documentation .

namespace Google\Cloud\Samples\Vision;

use Google\Cloud\Vision\V1\ImageAnnotatorClient;

// $path = 'path/to/your/image.jpg'

function detect_label($path)
{
    $imageAnnotator = new ImageAnnotatorClient();

    # annotate the image
    $image = file_get_contents($path);
    $response = $imageAnnotator->labelDetection($image);
    $labels = $response->getLabelAnnotations();

    if ($labels) {
        print("Labels:" . PHP_EOL);
        foreach ($labels as $label) {
            print($label->getDescription() . PHP_EOL);
        }
    } else {
        print('No label found' . PHP_EOL);
    }

    $imageAnnotator->close();
}

Python

Before trying this sample, follow the Python setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API Python API reference documentation .

def detect_labels(path):
    """Detects labels in the file."""
    from google.cloud import vision
    client = vision.ImageAnnotatorClient()

    with io.open(path, 'rb') as image_file:
        content = image_file.read()

    image = vision.types.Image(content=content)

    response = client.label_detection(image=image)
    labels = response.label_annotations
    print('Labels:')

    for label in labels:
        print(label.description)

Ruby

Before trying this sample, follow the Ruby setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API Ruby API reference documentation .

# project_id = "Your Google Cloud project ID"
# image_path = "Path to local image file, eg. './image.png'"

require "google/cloud/vision"

vision = Google::Cloud::Vision.new project: project_id
image  = vision.image image_path

image.labels.each do |label|
  puts label.description
end

Detecting Labels in a remote image

For your convenience, the Vision API can perform Label Detection directly on an image file located in Google Cloud Storage or on the Web without the need to send the contents of the image file in the body of your request.

Protocol

Refer to the images:annotate API endpoint for complete details.

To perform Label Detection, make a POST request and provide the appropriate request body:

POST https://vision.googleapis.com/v1/images:annotate?key=YOUR_API_KEY
{
  "requests": [
    {
      "image": {
        "source": {
          "gcsImageUri": "gs://YOUR_BUCKET_NAME/YOUR_FILE_NAME"
        }
      },
      "features": [
        {
          "type": "LABEL_DETECTION"
        }
      ]
    }
  ]
}

See the AnnotateImageRequest reference documentation for more information on configuring the request body.

C#

Before trying this sample, follow the C# setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API C# API reference documentation .

// Specify a Google Cloud Storage uri for the image
// or a publicly accessible HTTP or HTTPS uri.
var image = Image.FromUri(uri);
var client = ImageAnnotatorClient.Create();
var response = client.DetectLabels(image);
foreach (var annotation in response)
{
    if (annotation.Description != null)
        Console.WriteLine(annotation.Description);
}

Go

Before trying this sample, follow the Go setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API Go API reference documentation .

// detectLabels gets labels from the Vision API for an image at the given file path.
func detectLabelsURI(w io.Writer, file string) error {
	ctx := context.Background()

	client, err := vision.NewImageAnnotatorClient(ctx)
	if err != nil {
		return err
	}

	image := vision.NewImageFromURI(file)
	annotations, err := client.DetectLabels(ctx, image, nil, 10)
	if err != nil {
		return err
	}

	if len(annotations) == 0 {
		fmt.Fprintln(w, "No labels found.")
	} else {
		fmt.Fprintln(w, "Labels:")
		for _, annotation := range annotations {
			fmt.Fprintln(w, annotation.Description)
		}
	}

	return nil
}

Java

Before trying this sample, follow the Java setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API Java API reference documentation .

public static void detectLabelsGcs(String gcsPath, PrintStream out) throws Exception,
    IOException {
  List<AnnotateImageRequest> requests = new ArrayList<>();

  ImageSource imgSource = ImageSource.newBuilder().setGcsImageUri(gcsPath).build();
  Image img = Image.newBuilder().setSource(imgSource).build();
  Feature feat = Feature.newBuilder().setType(Type.LABEL_DETECTION).build();
  AnnotateImageRequest request =
      AnnotateImageRequest.newBuilder().addFeatures(feat).setImage(img).build();
  requests.add(request);

  try (ImageAnnotatorClient client = ImageAnnotatorClient.create()) {
    BatchAnnotateImagesResponse response = client.batchAnnotateImages(requests);
    List<AnnotateImageResponse> responses = response.getResponsesList();

    for (AnnotateImageResponse res : responses) {
      if (res.hasError()) {
        out.printf("Error: %s\n", res.getError().getMessage());
        return;
      }

      // For full list of available annotations, see http://g.co/cloud/vision/docs
      for (EntityAnnotation annotation : res.getLabelAnnotationsList()) {
        annotation.getAllFields().forEach((k, v) ->
            out.printf("%s : %s\n", k, v.toString()));
      }
    }
  }
}

Node.js

Before trying this sample, follow the Node.js setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API Node.js API reference documentation .

// Imports the Google Cloud client libraries
const vision = require('@google-cloud/vision');

// Creates a client
const client = new vision.ImageAnnotatorClient();

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// const bucketName = 'Bucket where the file resides, e.g. my-bucket';
// const fileName = 'Path to file within bucket, e.g. path/to/image.png';

// Performs label detection on the gcs file
client
  .labelDetection(`gs://${bucketName}/${fileName}`)
  .then(results => {
    const labels = results[0].labelAnnotations;
    console.log('Labels:');
    labels.forEach(label => console.log(label.description));
  })
  .catch(err => {
    console.error('ERROR:', err);
  });

PHP

Before trying this sample, follow the PHP setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API PHP API reference documentation .

namespace Google\Cloud\Samples\Vision;

use Google\Cloud\Vision\V1\ImageAnnotatorClient;

// $path = 'gs://path/to/your/image.jpg'

function detect_label_gcs($path)
{
    $imageAnnotator = new ImageAnnotatorClient();

    # annotate the image
    $response = $imageAnnotator->labelDetection($path);
    $labels = $response->getLabelAnnotations();

    if ($labels) {
        print("Labels:" . PHP_EOL);
        foreach ($labels as $label) {
            print($label->getDescription() . PHP_EOL);
        }
    } else {
        print('No label found' . PHP_EOL);
    }

    $imageAnnotator->close();
}

Python

Before trying this sample, follow the Python setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API Python API reference documentation .

def detect_labels_uri(uri):
    """Detects labels in the file located in Google Cloud Storage or on the
    Web."""
    from google.cloud import vision
    client = vision.ImageAnnotatorClient()
    image = vision.types.Image()
    image.source.image_uri = uri

    response = client.label_detection(image=image)
    labels = response.label_annotations
    print('Labels:')

    for label in labels:
        print(label.description)

Ruby

Before trying this sample, follow the Ruby setup instructions in the Vision API Quickstart Using Client Libraries . For more information, see the Vision API Ruby API reference documentation .

# project_id = "Your Google Cloud project ID"
# image_path = "Google Cloud Storage URI, eg. 'gs://my-bucket/image.png'"

require "google/cloud/vision"

vision = Google::Cloud::Vision.new project: project_id
image  = vision.image image_path

image.labels.each do |label|
  puts label.description
end

LABEL_DETECTION Response

A LABEL_DETECTION request produces a response containing a set of labelAnnotations of type EntityAnnotation.

The code example contains a sample label detection response for the top five matches for the photo shown below:

{
  "responses": [
    {
      "labelAnnotations": [
        {
          "mid": "/m/0bt9lr",
          "description": "dog",
          "score": 0.97346616
        },
        {
          "mid": "/m/09686",
          "description": "vertebrate",
          "score": 0.85700572
        },
        {
          "mid": "/m/01pm38",
          "description": "clumber spaniel",
          "score": 0.84881884
        },
        {
          "mid": "/m/04rky",
          "description": "mammal",
          "score": 0.847575
        },
        {
          "mid": "/m/02wbgd",
          "description": "english cocker spaniel",
          "score": 0.75829375
        }
      ]
    }
  ]
}
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