Nuke Reformat Node


I made a Matte Painting in 3600x1800. I am using it to create camera projections in nuke. I want my final nuke render to be 1920x1080. Now to do that, I used a reformat node but unfortunately, it is lowering the original quality of my matte painting. How do I reformat so that I could preserve the image quality? Or is it inevitable?