Operating on pixels as weakly-typed vectors of u8 is error-prone and inconvenient. It's better to use vectors of pixel structs. However, Rust is so strongly typed that your RGB pixel struct is not compatible with my RGB pixel struct. So let's all use mine :P

Add this to your Cargo.toml:

[dependencies]
rgb = "0.8"

The structs implement common Rust traits and a few convenience functions, e.g. map that repeats an operation on every subpixel:

use rgb::*; // Laziest way to use traits which add extra methods to the structs

let px = RGB {
    r:255_u8,
    g:0,
    b:255,
};
let inverted = px.map(|ch| 255 - ch);

println!("{}", inverted); // Display: rgb(0,255,0)
assert_eq!(RGB8::new(0, 255, 0), inverted);

For interoperability with functions operating on generic arrays of bytes there are functions for safe casting to and from pixel slices.

let raw = vec![0u8; width*height*3];
let pixels: &[RGB8] = raw.as_rgb(); /// Safe casts without copying
let raw_again = pixels.as_bytes();

Note: if you get an error about "no method named as_bytes found", add use rgb::ComponentBytes. If you're using a custom component type (RGB<CustomType>), implement rgb::Pod (plain old data) and rgb::Zeroable trait for the component (these traits are from bytemuck crate).

Correct color management is a complex problem, and this crate aims to be the lowest common denominator, so it's intentionally agnostic about it.

However, this library supports any subpixel type for RGB<T>, and RGBA<RGBType, AlphaType>, so you can use them with a newtype, e.g.:

struct LinearLight(u16);
type LinearRGB = RGB<LinearLight>;

There are other color types in rgb::alt::*. To enable ARGB and ABGR, use the "argb" feature:

rgb = { version = "0.8", features = ["argb"] }

There's also an optional serde feature that makes all types (de)serializable.