Uhhhh, if you shot your pictures in the "selective color" mode, they are not black & white or more to the point, if you wanted to take b&W photos, why use "selective color"? When using selective color, you point your camera at the color you want the camera to pick up. You then lock this in. You can do this for up to 3 colors. Those 3 colors that you have chosen or locked in, will be the colors that will show up in your picture. Everything else that is not one of those 3 colors, will be monochrome or B&W. THere is no need to try and do this in PP when you can do it in-camera if you set up the camera right. I just don't understand your statement, "What I want to do now is to add color to objects (cars) in the pics , leaving the rest of the pic B&W." That is what "selective color" does in the d5100, no need for PP. It's all in the manual.