org.springframework.cloud.stream.app.object.detection.processor.ObjectDetectionTensorflowInputConverter.java Source code

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Here is the source code for org.springframework.cloud.stream.app.object.detection.processor.ObjectDetectionTensorflowInputConverter.java

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/*
 * Copyright 2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License 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 org.springframework.cloud.stream.app.object.detection.processor;

import java.awt.image.BufferedImage;
import java.awt.image.DataBufferByte;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.HashMap;
import java.util.Map;
import javax.imageio.ImageIO;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.tensorflow.Tensor;
import org.tensorflow.types.UInt8;

import org.springframework.cloud.stream.app.tensorflow.processor.TensorflowInputConverter;

/**
 * Converts byte array image into a input Tensor for the Object Detection API. The computed image tensors uses the
 * 'image_tensor' model placeholder.
 *
 * @author Christian Tzolov
 */
public class ObjectDetectionTensorflowInputConverter implements TensorflowInputConverter {

    private static final Log logger = LogFactory.getLog(ObjectDetectionTensorflowInputConverter.class);

    private static final long BATCH_SIZE = 1;
    private static final long CHANNELS = 3;
    public static final String IMAGE_TENSOR_FEED_NAME = "image_tensor";

    @Override
    public Map<String, Object> convert(Object input, Map<String, Object> processorContext) {

        if (input instanceof byte[]) {
            try {
                Tensor inputImageTensor = makeImageTensor((byte[]) input);
                Map<String, Object> inputMap = new HashMap<>();
                inputMap.put(IMAGE_TENSOR_FEED_NAME, inputImageTensor);

                return inputMap;
            } catch (IOException e) {
                throw new IllegalArgumentException("Incorrect image format", e);
            }
        }

        throw new IllegalArgumentException(String.format("Expected byte[] payload type, found: %s", input));
    }

    private static Tensor<UInt8> makeImageTensor(byte[] imageBytes) throws IOException {
        ByteArrayInputStream is = new ByteArrayInputStream(imageBytes);
        BufferedImage img = ImageIO.read(is);

        if (img.getType() != BufferedImage.TYPE_3BYTE_BGR) {
            throw new IllegalArgumentException(
                    String.format("Expected 3-byte BGR encoding in BufferedImage, found %d", img.getType()));
        }
        byte[] data = ((DataBufferByte) img.getData().getDataBuffer()).getData();
        // ImageIO.read produces BGR-encoded images, while the model expects RGB.
        bgrToRgb(data);

        //Expand dimensions since the model expects images to have shape: [1, None, None, 3]
        long[] shape = new long[] { BATCH_SIZE, img.getHeight(), img.getWidth(), CHANNELS };

        return Tensor.create(UInt8.class, shape, ByteBuffer.wrap(data));
    }

    private static void bgrToRgb(byte[] data) {
        for (int i = 0; i < data.length; i += 3) {
            byte tmp = data[i];
            data[i] = data[i + 2];
            data[i + 2] = tmp;
        }
    }
}