I have discovered Gimp’s “Color to Alpha” feature, and man is it awesome! Basically, it will extract a particular color out of a selection and convert it to transparency. This gave me the ability to make a bottle taken on a flat background a truly transparent layer with highlights and shadows intact.
Does Adobe Photoshop have anything similar? Paid or otherwise? (Here’s my attempt at steps coming to around 60% quality of the Gimp plugin)