image.go
func (i *Image) Dispose() error {
	i.copyCheck()
	if i.isDisposed() {
		return nil
	}
	if i.isSubImage() {
		return nil
	}
	i.mipmap.dispose()
	i.resolvePendingPixels(false)
	return nil
}
func (i *Image) Dispose() error {
	i.copyCheck()
	if i.isDisposed() {
		return nil
	}
	if i.isSubImage() {
		return nil
	}
	i.mipmap.dispose()
	i.resolvePendingPixels(false)
	return nil
}
// Dispose disposes the image data. After disposing, most of image functions do nothing and returns meaningless values.
//
// Dispose is useful to save memory.
//
// When the image is disposed, Dipose does nothing.
//
// Dipose always return nil as of 1.5.0-alpha.