Just a quick look at the processing of the photos on the website DoNotDesign.org
I started by building a pallet for the website. I wanted to do something grim, so grabbing a Mark Rothko image for inspiration was a no brainer. It was also because I wanted to get a variety of colour options instead of pure black and white. It seems straight forward but there's obviously more complex hue information in any information from something like a painting.
So I grabbed an online image and converted it to a low quality gif. This gif reduced it to a simpler pallet. I throw this image into a little Adobe extra plug-in called ColorPickingTool (it's rad). In this I reduced the colour information further to a pallet I liked, and I can export the information as an ASE swatch (for all of the Illustrator kids), or as hex data which I prefer.
Next you can see my uneditted photo. Lovely. I wasn't sure what I needed so with a lot of these I had the sky contrast done splendidly or the foreground. Throw that into Photoshop (it's easier than Lightroom or CameraRaw for this) and strip the colour out in a rude, undynamic way (this is for the photos only, there is colour in the website background and fonts).
In levels you can not only pull in the edges of your black and white while mixing grey, but also reduce and control where you purest black and white are. I didn't realise that for years!
Then I pump contrast across the board in curves. I put all of the images through this for the website. After placing them in, only then did I work out the darkness I actually wanted to contrast the image against the titles. Most were left the same, but several were darkened.
It's like Instagram, but a heap more work.