Showing class values for different class types in one row
image_id | feature_id | feature_val
_________|____________|____________
  12     |    1       |     41
  12     |    2       |     82
  12     |    3       |     75

  74     |    1       |     23
  74     |    2       |     35
  74     |    3       |     72

image_id |  feature_1_val  | feature_2_val | feautre_3_val
_________|_________________|_______________|_______________
  12     |       41        |      82       |       75
  74     |       23        |      35       |       72

select  image_id
,       max(case when feature_id = 1 then feature_val end) as feature_1_val
,       max(case when feature_id = 2 then feature_val end) as feature_2_val
from    YourTable
group by
        image_id

SELECT it.image_id,
       (SELECT feature_val FROM ImageTable WHERE ImageTable.image_id = it.image_id AND ImageTable.feature_id = 1) AS feature_1_val,
       (SELECT feature_val FROM ImageTable WHERE ImageTable.image_id = it.image_id AND ImageTable.feature_id = 2) AS feature_2_val,
       (SELECT feature_val FROM ImageTable WHERE ImageTable.image_id = it.image_id AND ImageTable.feature_id = 3) AS feature_3_val
  FROM ImageTable AS it
  GROUP BY it.image_id