How to extract EXIF metadata from BLOB column - oracle

Question

I am trying to extract geolocation from EXIF metadata and the JPEG-image is stored in blob column in Oracle Database 12c using PLSQL.
Oracle Multimedia package is installed. The image contains data about geolocation before uploading, and when I download it again from the BLOB, latitude and longitude are there in metadata. But when I try to read it in database, I can read only basic metadata like image width, height, size, mimetype.
I am using this procedure to extract metadata from BLOB column:
PROCEDURE extractMetadata(inID IN INTEGER) IS
img ORDSYS.ORDIMAGE;
metav XMLSequenceType;
meta_root VARCHAR2(40);
xmlORD XMLType;
xmlXMP XMLType;
xmlEXIF XMLType;
xmlIPTC XMLType;
BEGIN
-- select the image
SELECT ordsys.ordimage(d.blob,1)
INTO img
FROM PHOTOS d
WHERE d.id = inID;
-- extract all the metadata
metav := img.getMetadata( 'ALL' );
-- process the result array to discover what types of metadata were returned
FOR i IN 1..metav.count() LOOP
meta_root := metav(i).getRootElement();
DBMS_OUTPUT.PUT_LINE(meta_root);
CASE meta_root
WHEN 'ordImageAttributes' THEN xmlORD := metav(i);
WHEN 'xmpMetadata' THEN xmlXMP := metav(i);
WHEN 'iptcMetadata' THEN xmlIPTC := metav(i);
WHEN 'exifMetadata' THEN xmlEXIF := metav(i);
ELSE NULL;
END CASE;
END LOOP;
-- Update metadata columns
--
update photos SET metaORDImage = xmlORD,
metaEXIF = xmlEXIF,
metaIPTC = xmlIPTC,
metaXMP = xmlXMP
WHERE id = inID;
END extractMetadata;
but only metaORDImage is extracted.
It seems like there is no EXIF metadata available, but when I download image to my PC and check details, there is location data:
What could be wrong here? Is it possible at all to extract EXIF from BLOB and should I store the image in some other format rather than BLOB?
UPDATE: I used Javascript library exif-js to read metada on page when the image is loaded into webpage, and once again geolocation is there. I can read it anywhere but not in PLSQL.
{
"ImageWidth": 720,
"ImageHeight": 1520,
"ExifIFDPointer": 74,
"Orientation": 0,
"GPSInfoIFDPointer": 92,
"LightSource": "Unknown",
"GPSLatitude": [
43,
xx,
17.861
],
"GPSLatitudeRef": "N",
"GPSLongitudeRef": "E",
"GPSLongitude": [
17,
xx,
7.29
],
"thumbnail": {}
}

Answer 1

My proposal would be a Java class, e.g. Apache Commons Imaging or org.w3c.tools.jpeg or metadata-extractor
First you need to load the Java classes into your database. Can be done with the loadjava tool:
loadjava -verbose -user username/password#DATABASE_NAME -r -o .\commons-imaging-1.0-alpha3.jar
Then you need to define the PL/SQL procedure/function:
CREATE OR REPLACE FUNCTION getMetadata(img IN BLOB) RETURN VARCHAR2
AS LANGUAGE JAVA NAME 'Imaging.getMetadata(byte[] bytes) return java.lang.String';
/
In the final step you can use the PL/SQL as usual. Above function does not work, because of wrong return type but I hope you get an idea how it works in general.
See Calling Java Methods in Oracle Database and https://www.tabnine.com/code/java/classes/oracle.sql.BLOB