I want to store some image descriptors on a server so that when image matching on an android phone I can fetch the precomputed image descriptors rather then doing it on the fly. I have successfully created an application that can take an input image and output the best match but I am having some trouble with placing the image descriptor matrix into a JSON file.
Below I have placed some code that I have tried to adapt to perform the function I want but I run into an error with these lines:
mat.get(0, 0, data);
The error it gives is:
Mat data type is not compatible: 5
The descriptor matrix is of type CV_32FC1 but it treats it as CV_8SC1. Full code is underneath, the idea is that I will pass in descriptor matrix to matToJson and then store the output on the server and then use matFromJson to retrieve the contents of the JSON file. I also cannot resolve Base64.DEFAULT as it shows an error. Any help would be greatly appreciated.
public static String matToJson(Mat mat){
JsonObject obj = new JsonObject();
if(mat.isContinuous()){
int cols = mat.cols();
int rows = mat.rows();
int elemSize = (int) mat.elemSize();
byte[] data = new byte[cols * rows * elemSize];
mat.get(0, 0, data);
obj.addProperty("rows", mat.rows());
obj.addProperty("cols", mat.cols());
obj.addProperty("type", mat.type());
// We cannot set binary data to a json object, so:
// Encoding data byte array to Base64.
String dataString = new String(Base64.encode(data, Base64.DEFAULT)); //Error here as well .default does not exist
obj.addProperty("data", dataString);
Gson gson = new Gson();
String json = gson.toJson(obj);
return json;
} else {
System.out.println("Mat not continuous.");
}
return "{}";
}
public static Mat matFromJson(String json){
JsonParser parser = new JsonParser();
JsonObject JsonObject = parser.parse(json).getAsJsonObject();
int rows = JsonObject.get("rows").getAsInt();
int cols = JsonObject.get("cols").getAsInt();
int type = JsonObject.get("type").getAsInt();
String dataString = JsonObject.get("data").getAsString();
byte[] data = Base64.decode(dataString.getBytes(), Base64.DEFAULT);
Mat mat = new Mat(rows, cols, type);
mat.put(0, 0, data);
return mat;
}
