# Image of linear projection

Let $X \subset \mathbb{P}^n$ be a projective variety (i.e. zariski closed), and let $\pi : X \dashrightarrow \mathbb{P}^m$ a linear projection ($\pi$ is not in every point of $X$ defined).

Under which conditions is the image $\pi(X)$ zariski closed? What criterions are known?

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