decode image data from a HTTP string response. (Elm 0.18) - image

Question

I'd like to fetch an image from a remote server and load it into the following data structure:
type alias Pixel = { r : Int, g : Int, b: Int, a: Float }
type alias ImageData = { pixels : Array Pixel, width: Int }
In the project for some reasons I'm still using Elm 0.18, and elm-lang/http only let's you handle strings as responses from http requests.
init : ( Model, Cmd Msg )
init =
( {}
, Http.send
(\response ->
case response of
Ok data ->
let
_ =
Debug.log "ok" data
in
NoOp
Err error ->
let
_ =
Debug.log "error" error
in
NoOp
)
(Http.getString "https://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/Creamer_MET_186969.jpg/2px-Creamer_MET_186969.jpg")
)
This logs:
ok: "����\0C\0\n\r\t\n\n\r\r��\0\v\0\0\"\0��\0\0\0\0\0\0\0\0\0\0\0\t\n\v��\0�\0\0\0}\0!1AQa\"q2���#B��R��$3br�\t\n%&'()*456789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz���������������������������������������������������������������������������\0\0\0?\0�9�(�.t�/���=~���"
But how to convert it into the above data structure? Also, does it matter if the image is a jpg, png, gif?
What I'm looking for is the implementation of a function imageDataFromString : String -> Maybe ImageData
note: I'd prefer a non-port solution even if performance will be lower, the images I'm trying to process are not large.