Software Informer's Senior editor Francisco Martínez scores ColorVeil 5 out of 5 stars and awards it the Editor's Pick Award for excellence.
Whatever your reasons are to require or prefer a specific screen color with a certain opacity level for your screen (dyslexia, SSS, or just plain eye strain), ColorVeil is probably the most flexible, convenient, and efficient solution you'll surely find out there.
This completely free tool is so tiny that anyone can download it and benefit from it in a snap. Easy to toggle on and off and just as simple to configure, you can take ColorVeil's portable version with you everywhere and use it on any computer without even installing it. I can't honestly find a reason not to have it installed on your workstation.