We don't need any special types and will use basic types of the actix crate and import types from the image crate that we've used before:

use actix::{Actor, Handler, Message, SyncContext};
use image::{ImageResult, FilterType};

type Buffer = Vec<u8>;

We'll convert the function body from previous examples in this chapter in handler implementation that's why we imported types from the image crate. We added the Buffer alias to the Vec<u8> type for convenience.