PowerToys is a bundle of really great... well, Power tools that will add some great resources and handy tools to your arsenal. One of those is the Color Picker.
Color picker will allow you to set a global shortcut (Mine is Alt+X) to pop up a color picker that will let you pick any color on your screen, and remember previous choices
It will display the color in HEX, RGB and HSL by default - with a convenient "Copy to clipboard" button to the right. In the settings, you can choose between many different ways of displaying the color information:
When it comes to using a color picker, there are tons of alternatives with lots of functionality, but I find that the PowerToys color picker works just right for me - and with the added bonus of the remaining apps that come with PowerToys as well.
In order to download and install PowerToys, follow the link here:
Microsoft PowerToys is a set of utilities for power users to tune and streamline their Windows experience for greater productivity. The currently available utilities include: Currently, PowerToys is available in the following languages: Chinese (simplified), Chinese (traditional), Czech, Dutch, English, French, German, Hungarian, Italian, Japanese, Korean, Polish, Portuguese, Portuguese (Brazil), Russian, Spanish, Turkish.
There is some good information on what kinds of tools PowerToys includes in there, so make sure to take a look!