Let's say that I have a picture of 4 different colored cars. Black, White, Green, and light blue. I want to make all of these the same shade of yellow. If you ignore black I can use Colors, Hue-Saturation to change the color, but getting it to the yellow I want is trial and error. Getting the next car to be the same yellow would be harder. Colors, Map, Color Exchange allows me to pick the destination color, but it is still trial and error. I may get one car to look the correct yellow, but the other one won't. I have also tried all of the modes. The black car seems to be a bigger problem.
Is there a way to select the green part of the car and change it to a yellow that I picked up with the dropper (or specify is some other way)? I then want to do the same to the light blue car and have it be the same yellow.
Thanks for any help.