how to change Product Image orientation from horizontal to vertical?

Hi,

HikaShop uses the GD library available by default with PHP to process images.
Unfortunately, GD doesn't take into account the EXIF data of images.
This has been an open issue for many years:
github.com/libgd/libgd/issues/341
Because of that, when the tool used to capture the image used the EXIF data of the image to specify the rotation of the image, instead of really rotating the image, the thumbnails generated from these images ignore the rotation in the EXIF data and thus the thumbnails look rotated.
Unfortunately, it seems that for GD to include this will require many more years of waiting.
So we actually worked on this many years ago to manually process the EXIF data.
And thus, since HikaShop 3.3.0, HikaShop will take into account the EXIF data to auto rotate the images for the thumbnails.

However:
- if the images was uploaded and used on an HikaShop older than this version, even if you updated later on, the thumbnails generated from the original image would still not be regenerated and thus would still not take into account the EXIF rotation.
- similarly, before PHP 7.2, many EXIF formats where not supported by PHP ( www.php.net/manual/en/function.exif-read-data.php ), even with the code in HikaShop, it couldn't read the EXIF data properly. So if you uploaded the image before moving to a version of PHP newer than 7.1, you would have to same problem.

This all means that normally, if you delete the images/com_hikashop/upload/thumbnails/ folder in order to let HikaShop generate the thumbnails, since you're using a recent version of PHP and a recent version of HikaShop, it should normally regenerate automatically the thumbnails with the correct auto rotation.
I actually tried to use your image on HikaShop 4.7.5 with PHP 8.1 on my end, and the auto rotation was properly taken into account.

Hello,

It's a bit of a hack but why not use CSS?

Now it remains to be seen whether this can be suitable in all cases, and especially the sizes of your images.
If on the product page the main image is always the same then there is a good chance that it will work with very little adjustment

Example :

.hikashop_product_page div#hikashop_main_image_div img {
    transform: rotate(90deg);
}