In getProductDetails respone, due to code dependencies of Internal eBay applications, both the Standard version and the thumbnail version of the stock Photo url return the 70 pixel images. However you can retreive a high resolution image by foloowing a simple workaround.
Afetr you retreive the below response :
[stockPhotoURL] =>
(
[thumbnail] =>
(
[value] => http://i.ebayimg.com/00/$(KGrHqNHJ!sE7yCShryfBPGQY,brQg~~_0.JPG?set_id=89040003C1
)
[standard] =>
(
[value] => http://i.ebayimg.com/00/$(KGrHqNHJ!sE7yCShryfBPGQY,brQg~~_7.JPG?set_id=89040003C1
)
)
If you change the 7 to 32 you get a larger resolution image
<standard><value>http://i.ebayimg.com/00/$(KGrHqNHJ!sE7yCShryfBPGQY,brQg~~_7.JPG?set_id=89040003C1</value>
http://i.ebayimg.com/00/$%28KGrHqR,!h!E2e2gC%28qqBNuZU!Hqcw~~_32.JPG?set_id=89040003C1
Please implement this workaround programatically after you retreive the Stock photo Urls.