Question: I have this section of the wall just above my bed, recently it became a bit dirty so I used a sponge to clean it. Unfortunately now I'm left with a a big green mark on the wall and it wont go away.

I think the only way it to paint over it . is there any other option ?

If I paint that half a meter squared section I donx't want it to much noticeable from the rest of the room
What should I do ?

[![enter image description here](https://i.stack.imgur.com/p2Q1H.jpg)](https://i.stack.imgur.com/p2Q1H.jpg)

Answer: 
It looks like you scrubbed away the top layer of paint. There's no way to scrub it back on. 

If you have the paint, you can easily blend it in, though fading due to age may result in it being slightly conspicuous. 

If not, get a paint match (for both color and sheen) and paint the entire wall.
Looks like the sponge got dissolved or the old paint shines through. I would prime that area and paint the complete wall from corner to corner. I never had much success in fixing a small area. On the other hand, I have a hard time ignoring imperfections exspecially when I caused them. Also, patching takes usually as long as doing the complete wall.

It comes down to if you can ignore something shining through after fixing?