responsive photogallery portrait pictures

[StrikeWyrm]

im trying to use the code provided in the w3school's responsive image gallery (https://www.w3schools.com/css/tryit.asp?filename=trycss_image_gallery_responsive) and the basic code works but when i substitute any of the pictures for a portrait rather than a landscape it rotates the portrait image 90 degrees so that it ends up landscape... i am using the exact same code with the exceptions of the images im trying to use

[dsonesuk]

That code has no way of determining what type image to rotate OR actually rotating a image on its own. it is more likely how the image was saved or some other code that is doing the rotating.