I have hundreds of product image layers and I am trying to resize them all to the same height (ignoring the width) and retaining their individual aspect ratio's.
Is there a script available that does this? Or a feature I am unaware of?
What you are trying to do can be done with actions and batch.
(1) Go to your actions tab (Window>Actions if its not already on your workspace).
(2) (a.) Create a new action set. (b.) Create a new action.
Now you can do a batch automation.
I'm not sure what you meant by image layers though. (It sounds like you are talking about layers in a particular document??) Above, I'm assuming you have a folder full of images of all different dimensions and want to resize them so that every image is height = x.