Image

Given a function $f:X \rightarrow Y$ between two sets, the image of subset $A$ of $X$ under $f$ is the set of all outputs of $f$ for the inputs limited to $A$: $$f(A)=\{f(x):x \in A\}.$$ In particular, the image is $$\it{im} f = f(A).$$ Aka the range.

See also preimage.