code: public static byte[] getImageData( IHMConnection connection, long imageDataId ) throws Exception {
          String sql = "select " + //
                  ImageDataTableFields.COLUMN_IMAGE.getFieldName() + //
                  " from " + TABLE_IMAGE_DATA + " where " + //
                  ImageDataTableFields.COLUMN_ID.getFieldName() + " = " + imageDataId;
  
          try (IHMStatement statement = connection.createStatement(); IHMResultSet rs = statement.executeQuery(sql);) {
              statement.setQueryTimeout(30); // set timeout to 30 sec.
  
              if (rs.next()) {
                  byte[] bytes = rs.getBytes(1);
                  return bytes;
              }
          }
          return null;
      }
docs: Get Image data from data id.
  
  @param connection
  @param imageDataId
  @return
  @throws Exception