How to have header.image relative to page location

[positron96]

Hi.
I have images in the same folder as the page (the page itself ends up in {site.url}/projects/myproject/index.html) and I'd like to have this page show the image in header:

---
layout: single
title:  "some title"
header:
  image: image1.png
---

![](image2.png)

While in page contents image2.png is shown properly (the image has a src="image2.png" as expected), in the header the link becomes "{site.url}/image1.png", which does not exist.

Is there a way to make image1 relative to the page location, without specifying the path in the page itself?