First, you'll need to make an ajax request that sets the headers. Then, you need to use some HTML5 APIs to convert binary data recieved to base64. Finally, set the image src with the data: protocol and your base64 data.

var oReq = new XMLHttpRequest();

oReq.open(GET, yourpage.jsp, true);

oReq.setRequestHeader(Your-Header-Here, Value);

// use multiple setRequestHeader calls to set multiple values

oReq.responseType = arraybuffer;

oReq.onload = function (oEvent) {

  var arrayBuffer = oReq.response; // Note: not oReq.responseText

  if (arrayBuffer) {

    var u8 = new Uint8Array(arrayBuffer);

    var b64encoded = btoa(String.fromCharCode.apply(null, u8));

    var mimetype=image/png; // or whatever your image mime type is

    document.getElementById(yourimageidhere).src=data:+mimetype+;base64,+b64encoded;

  }

};

oReq.send(null);

Sources:

https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Sending_and_Receiving_Binary_Data

How to convert uint8 Array to base64 Encoded String?