Load an image from NodeJS sendFile using authHttp

In Node JS I am using res.sendFile to send an image to an Ionic2 app.
If I use a direct url in the src, it works fine:
<img src="https://somefunkyserver.com:3000/image?id={{fileurl}}" />
That works.

But I would like to use authHttp to do it to authenticate user before accessing image:
I have tried a number of ways but either get blankness or unsafe url warnings or non url schema:

<img src='this.authHttp.get("https://somefunkyserver.com:3000/image?id={{fileurl}}")'/>

<img src="get_image(fileUrl) where I can successfully use authHttp to get the image from the node sendFile but cannot display it.

I have tried base64 conversion after loading but still nothing.
I tried prepending the image data with "data:image/jpeg;base64,"
If I console.log the data returned, I get a lot of image data but will not display.
I also tried utilizing canvas for this but still blankness where an image should be.

When I use:
return this.authHttp.post("https://somefunkyserver.com:3000/image", json, options)
…where the fileUrl is passed in JSON, it gets the file OK but again, cannot display it.

Maybe I need to use Base64 in another way?