Changing color pict in grey excepted one color

[rich2005]

(08-16-2024, 01:20 PM)Gypsie38 Wrote: An example, 
a color picture in the street with cars. I want to change this picture in grey excepted keeping the color of one car
Thnaks

If you look at this example https://www.gimp.org/tutorials/Layer_Mas...on-example It shows how you might do it using a layer mask.