Anakin and Obi-Wan’s last conversation as friends, a brothers’ farewell.
It’s pretty obvious that this scene was deliberate kept rather black and white. There is not much color in it and Anakin is - repeatedly in this movie - being asked to stay in the dark. Another good example is later in the movie when Mace askes Anakin to stay in the Temple and Anakin is therefore forced to go back into the dark hangar interior.
Obi-Wan leaves with a bright daytime setting his back whereas Anakin is ordered to stay on Coruscant, although he wishes he could help Obi-Wan in his mission to capture Grievous. His background is distinctively darker.
That recurring theme and image in Revenge Of The Sith - which is Anakin being asked by the Jedi to stay back in dark territory - is taken to the extreme in this scene, though, especially when Anakin is shown almost identically framed in two shots but with very different brightness and one with Obi-Wan and the other without the Jedi Master.
The first one captures the moment when Obi-Wan praises Anakin and gives him confidence, saying: You are strong and wise, Anakin, and I am very proud of you. I have trained you since you were a small boy. I have taught you everything I know. And you have become a far greater Jedi than I could ever hope to
be.
The other one shows a moment only seconds after Obi-Wan has left.He left Anakin to be lost, lost in darkness and evil promises.