i am not able to get image column using database query 

mthod:

@ api.model 
def _get_report_values ( self , docids , data = None ): 
    model = self .env.context.get ( 'active_model' ) 
    self ._cr.execute ( "" "select DISTINCT first_name, image_1920,     x_id_number_student, blood_group, birth_date, name from op_student
    inner join op_student_course 
    on op_student.id = op_student_course.student_id 
    inner join op_course 
     on op_course.id = op_student_course.course_id "" " ) 
    docs = self ._cr.fetchall () 
    logging.info ("************************************************** 8 " ) 
    logging.info (docs) 
     
return {    'doc_ids' : self .ids , 
'doc_model' : model ,
'docs' : docs , 
'data' : data }