ai.djl.translate

Interface Translator<I,O>

Type Parameters:

I - the input type

O - the output type

All Superinterfaces:

PostProcessor<O>, PreProcessor<I>

All Known Implementing Classes:

FileTranslator, ImageClassificationTranslator, ImageTranslator, InputStreamTranslator, InstanceSegmentationTranslator, NoopTranslator, SimplePoseTranslator, SingleShotDetectionTranslator, UrlTranslator

public interface Translator<I,O>
extends PreProcessor<I>, PostProcessor<O>

The Translator interface provides model pre-processing and postprocessing functionality.

Users can use this in Predictor with input and output objects specified. The following is an example of processing an image and creating classification output:

 private static final class MyTranslator implements Translator<BufferedImage, Classification> {

     private int imageWidth;
     private int imageHeight;
     private Shape shape;

     public MyTranslator(int imageWidth, int imageHeight) {
         this.imageWidth = imageWidth;
         this.imageHeight = imageHeight;
         shape = new Shape(1, 3, imageWidth, imageHeight);
     }

     @Override
     public NDList processInput(TranslatorContext ctx, BufferedImage input) {
         BufferedImage image = Images.resize(input, imageWidth, imageHeight);
         FloatBuffer buffer = Images.toFloatBuffer(image);

         return new NDList(ctx.getNDManager().create(buffer, shape));
     }

     @Override
     public Classification processOutput(TranslatorContext ctx, NDList list) throws TranslateException {
         Model model = ctx.getModel();
         NDArray array = list.get(0).at(0);
         NDArray sorted = array.argSort(-1, false);
         NDArray top = sorted.at(0);

         float[] probabilities = array.toFloatArray();
         int topIndex = top.toIntArray()[0];

         String[] synset;
         try {
             synset = model.getArtifact("synset.txt", MyTranslator::loadSynset);
         } catch (IOException e) {
             throw new TranslateException(e);
         }
         return new Classification(synset[topIndex], probabilities[topIndex]);
     }

     private static String[] loadSynset(InputStream is) {
         ...
     }
 }
 

Method Summary

Modifier and Type	Method and Description
default Batchifier	getBatchifier() Gets the Batchifier.
default void	prepare(NDManager manager, Model model) Prepares the translator with the manager and model to use.

Methods inherited from interface ai.djl.translate.PreProcessor

getPipeline, processInput

Methods inherited from interface ai.djl.translate.PostProcessor

processOutput

Method Detail

getBatchifier

default Batchifier getBatchifier()

Gets the Batchifier.

Returns:

the Batchifier

prepare

default void prepare(NDManager manager,
                     Model model)
              throws java.io.IOException

Prepares the translator with the manager and model to use.

Parameters:

manager - the manager for the translator

model - the model to translate for

Throws:

java.io.IOException - if there is an error reading inputs for preparing the translator