… for Adobe Premiere Pro CC
Tip #609: What Does Uniform Scale Do?
Disabling Uniform Scale allows stretching images assymetrically.
By default, when you scale (resize) an image, Premiere maintains the aspect ratio. This means the image gets larger or smaller, but retains its overall shape. But, what if that’s not what you want?
When Uniform Scale is checked, whenever you adjust the size of an image, both height and width scale in proportion. This retains the overall shape (aspect ratio) of an image.
When Uniform Scale is unchecked, horizontal and vertical size can be scaled independently. This allows for some very interesting – and weird – visual effects. Especially when you keyframe the size changes over time.