ai.djl.modality.cv.translator.SingleShotDetectionTranslator Maven / Gradle / Ivy
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/*
* Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
* with the License. A copy of the License is located at
*
* http://aws.amazon.com/apache2.0/
*
* or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
* OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
* and limitations under the License.
*/
package ai.djl.modality.cv.translator;
import ai.djl.modality.cv.output.BoundingBox;
import ai.djl.modality.cv.output.DetectedObjects;
import ai.djl.modality.cv.output.Rectangle;
import ai.djl.ndarray.NDArray;
import ai.djl.ndarray.NDList;
import ai.djl.translate.TranslatorContext;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
* A {@link BaseImageTranslator} that post-process the {@link NDArray} into {@link DetectedObjects}
* with boundaries.
*/
public class SingleShotDetectionTranslator extends ObjectDetectionTranslator {
/**
* Creates the SSD translator from the given builder.
*
* @param builder the builder for the translator
*/
public SingleShotDetectionTranslator(Builder builder) {
super(builder);
}
/** {@inheritDoc} */
@Override
public DetectedObjects processOutput(TranslatorContext ctx, NDList list) {
float[] classIds = list.get(0).toFloatArray();
float[] probabilities = list.get(1).toFloatArray();
NDArray boundingBoxes = list.get(2);
List retNames = new ArrayList<>();
List retProbs = new ArrayList<>();
List retBB = new ArrayList<>();
for (int i = 0; i < classIds.length; ++i) {
int classId = (int) classIds[i];
double probability = probabilities[i];
// classId starts from 0, -1 means background
if (classId >= 0 && probability > threshold) {
if (classId >= classes.size()) {
throw new AssertionError("Unexpected index: " + classId);
}
String className = classes.get(classId);
float[] box = boundingBoxes.get(i).toFloatArray();
// rescale box coordinates by width and height
double x = width > 0 ? box[0] / width : box[0];
double y = height > 0 ? box[1] / height : box[1];
double w = width > 0 ? box[2] / width - x : box[2] - x;
double h = height > 0 ? box[3] / height - y : box[3] - y;
Rectangle rect;
if (applyRatio) {
rect = new Rectangle(x / width, y / height, w / width, h / height);
} else {
rect = new Rectangle(x, y, w, h);
}
retNames.add(className);
retProbs.add(probability);
retBB.add(rect);
}
}
return new DetectedObjects(retNames, retProbs, retBB);
}
/**
* Creates a builder to build a {@code SingleShotDetectionTranslator}.
*
* @return a new builder
*/
public static Builder builder() {
return new Builder();
}
/**
* Creates a builder to build a {@code SingleShotDetectionTranslator} with specified arguments.
*
* @param arguments arguments to specify builder options
* @return a new builder
*/
public static Builder builder(Map arguments) {
Builder builder = new Builder();
builder.configPreProcess(arguments);
builder.configPostProcess(arguments);
return builder;
}
/** The builder for SSD translator. */
public static class Builder extends ObjectDetectionBuilder {
/** {@inheritDoc} */
@Override
protected Builder self() {
return this;
}
/**
* Builds the translator.
*
* @return the new translator
*/
public SingleShotDetectionTranslator build() {
validate();
return new SingleShotDetectionTranslator(this);
}
}
}