How to get this kind of white with post-processing?

[blackwalla]

I've been wondering for a long time now how to get this kind of "white" through post-processing. (The ones on the windows to be exact.) If anybody knows how to get a result like this, please tell me how?

Thank you!
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[Peano]

A couple of ways ...

1. Open a selective color adjustment layer. In the whites panel, adjust the color sliders to get the off-white that you want. You can also increase black levels slightly to make whites a bit less bright if you prefer.
   
2. With levels of curves, double click the white dropper. In the color picker that opens, change the hue from white to the off-white that you want. Click OK, then click the white dropper on a white area of the image.