\begin{definition}[Definition:Image (Category Theory)]
Let $\CC$ be a locally small category.
Let $f : X \to Y$ be a morphism in $\CC$.
An '''image''' of $f$ consists of an object $I$ and a monomorphism $m: I \to Y$ such that:
:$(1): \quad$ There exists a morphism $e : X \to I$ such that $f = m \circ e$.
:$(2): \quad$ For any object $I'$ with a morphism $e' : X \to I'$ and a monomorphism $m' : I' \to Y$ such that $f = m' \circ e'$, there exists a unique morphism $v : I \to I'$ such that $m = m' \circ v$.
\end{definition}