sprite_get_height

With this function you can find the height of the base sprite asset, with no transforms, in pixels.

Syntax:

sprite_get_height(index);

Returns

Real

Example:

if (sprite_height != sprite_get_height(sprite_index))
{
    image_yscale = 1;
}

The above code checks the height of the sprite as it is in the current instance and if there is a difference between that and the original base sprite, it resets the y axis scale.