image.go
func NewImage(width, height int, filter Filter) (*Image, error) {
	s := shareable.NewImage(width, height)
	i := &Image{
		mipmap: newMipmap(s),
		filter: filter,
	}
	i.addr = i
	return i, nil
}
func NewImage(width, height int, filter Filter) (*Image, error) {
	s := shareable.NewImage(width, height)
	i := &Image{
		mipmap: newMipmap(s),
		filter: filter,
	}
	i.addr = i
	return i, nil
}
// NewImage returns an empty image.
//
// If width or height is less than 1 or more than device-dependent maximum size, NewImage panics.
//
// filter argument is just for backward compatibility.
// If you are not sure, specify FilterDefault.
//
// Error returned by NewImage is always nil as of 1.5.0-alpha.