How can I recreate this effect in GIMP? Blue/white color conversion

Question

Here is the image:

The best way I can describe it is converting the image to a black/white scale (heavy white) and making all instances of black==blue.That was how I approached it when trying to recreate the effect, but had little success. I prefer a solution that is doable in GIMP, since I don't have access to any other power image editing software.

EDIT: Thanks a ton to everyone for the help. There wasn't a single asnwer here that got me exactly where I wanted to be, but they all did help. And since I know what its like to come across threads like this one, I thought I'd show my progress and what I did differently.

First, Here is the raw image I was working with for demonstration purposes.

Then, trying what one answer suggested, I created a second layer of the blue-ish color like in my example, and did a [Right Click Image] Colors-> Map-> Gradient map, but it wasn't exactly what I was looking for:

This lead me to trying the other options in that same submenu, and I came across the Palette Map option. I selected a palette of exactly 2 colors 25408f & f7f7f7 (blue and white), which got much closer to the desired output:

This is VERY close to what I was hoping to get, but I'm still not 100% satisfied. I have been playing with the Posterize/contrast tools and expect I'll find a balance that I like eventually. Again, thanks to everyone that posted.

Answer 1

Gimp 2.8 does have a Gradient Map just like Photoshop. It is under Color > Map > Gradient Map.

1. Open your image in Gimp.
2. Make a second layer underneath and fill it with the color you want to show through, in this case a blue or purple color.
3. Then with your top image selected, hit the Gradient Map. You might want to make the top image high-contrast to get the look in your example.

This might get you close.