com.ibm.streamsx.edgevideo.device.edgent.JsonMat.java Source code

Introduction

Here is the source code for com.ibm.streamsx.edgevideo.device.edgent.JsonMat.java

Source

/*
# Licensed Materials - Property of IBM
# Copyright IBM Corp. 2017
 */
package com.ibm.streamsx.edgevideo.device.edgent;

import java.util.Base64;
import java.util.Base64.Decoder;
import java.util.Base64.Encoder;

import org.opencv.core.Mat;
import org.opencv.core.Size;
import org.opencv.imgproc.Imgproc;

import com.google.gson.JsonObject;

/**
 * OpenCV Mat to/from JsonObject
 * 
 * TODO semi-lame, presumably base64 of jpg or png would be better.
 */
public class JsonMat {

    public static JsonObject toJsonObject(Mat mat) {
        JsonObject jo = new JsonObject();
        jo.addProperty("width", mat.width());
        jo.addProperty("height", mat.height());
        jo.addProperty("type", mat.type());
        jo.addProperty("channels", mat.channels());
        jo.addProperty("depth", mat.depth());
        jo.addProperty("mat", base64MimeEncodeMat(mat));
        return jo;
    }

    public static Mat fromJsonObject(JsonObject joMat) {
        int width = joMat.getAsJsonPrimitive("width").getAsInt();
        int height = joMat.getAsJsonPrimitive("height").getAsInt();
        int type = joMat.getAsJsonPrimitive("type").getAsInt();
        Mat face = JsonMat.base64MimeDecodeMat(width, height, type, joMat.get("mat").getAsString());
        return face;
    }

    private static String base64MimeEncodeMat(Mat mat) {
        int width = mat.width(), height = mat.height(), channels = mat.channels();

        // resize if needed
        // With initial resize factor of 4 and being within 2' of the MBP camera,
        // a face image seems to be on the order of 15Kb.
        if (width * height * channels > 50 * 1024) {
            Mat smallerFace = new Mat();
            int resizeFactor = 2;
            Imgproc.resize(mat, smallerFace, new Size(mat.width() / resizeFactor, mat.height() / resizeFactor));
            mat = smallerFace;
            width = mat.width();
            height = mat.height();
            channels = mat.channels();
        }

        byte[] sourcePixels = new byte[width * height * channels];
        mat.get(0, 0, sourcePixels);

        // Base64 encode the image to be able to package in JsonObject
        // java.utils.Base64 since 1.8, otherwise use Apache Commons
        Encoder encoder = Base64.getMimeEncoder();
        String base64 = encoder.encodeToString(sourcePixels);

        //System.out.println("pub face bytes size: " + sourcePixels.length + " base64 size:" + base64.length());

        return base64;
    }

    private static Mat base64MimeDecodeMat(int width, int height, int type, String base64MimeMatStr) {
        // java.utils.Base64 since 1.8, otherwise use Apache Commons
        Decoder decoder = Base64.getMimeDecoder();
        byte[] sourcePixels = decoder.decode(base64MimeMatStr);

        //System.out.println(String.format("base64DecodeMat: width=%d height=%d type=%d", width, height, type));

        Mat mat = new Mat(height, width, type);
        mat.put(0, 0, sourcePixels);

        return mat;
    }

}