I have gotten an issue with my Mac LCD display, after the Mac was dropped. 100% white colors become pink and 100% black colors become green. I don't want to get it fixed, because that would be very expensive. I have instead managed to calibrate the white color, to a bit off-white, so that it is not pink. But how can I change the black color, so that it is just a tad grayish?
The color changes indicates the possibility of a loose, flat-band cable connection between the LCD display and the mainboard.
That DIY does not cost anything (but it is not easy to do) and might help in your case to make sure the cable connection is firm on both sides.
Go to ifixit and find your Macs instructions (or similar model) if not available.
If it is not the cable, you have 2 choices:
Replace the screen your self to save money.
Use the ColorSync app in the Utility folder and modify the colors profiles there.