If you are on a budget and aren't satisfied with the graphics utilities that come with your computer's operating system, these offerings are worth taking a serious look at. I've used many of them myself and have looked at dozens of others. This is a short list of my favorites.
"Free" means you might have to register or sign up and provide an email address. Some applications are open-source. All of the applications listed here are fully functional with no time or usage limitations.
Graphics Utilities (Stand-Alone and Web-Based)
Pixel Color PickersColorPic
Pick up the colors of individual pixels and palettes of up to 16 colors at once and use four advanced color mixers. Copy and paste RGB and HEX values.
Grab the pixel under your mouse and transform it into a number of different color formats. Small and fast. Copy RGB and HEX values.
This is a browser extension that assists with color related tasks - both basic and advanced. It includes a Color Picker, Eye Dropper, Gradient Generator and other advanced tools. Grab a color reading from any point in your browser, change it and paste it into another program. You can analyze the page and inspect its colors. You can also create advanced multi-stop CSS gradients.
Web-Based Color Referencers, Converters and SchemersColorSchemer.com
RGB-to-HEX conversion, color harmonies, monitor calibration and other utilities.
Adobe Color CC (formerly Adobe Kuler)
Adobe Color CC lets you try out, create and save various color schemes. It is available in browser-hosted variants, and in desktop versions and as a mobile app.
Screen CaptureFastStone Image Viewer
Screen-capture and much more. Basic image editing, file browsing, slide-shows, email. Free for non-commercial and educational use.
Paint and Photo-Editing (raster-based)Paint.net
Image and photo manipulation software for Windows. Basic Photoshop-like tools, reasonably sophisticated. Requires Microsoft .NET Framework 4.5.
This previous version or Serif DrawPlus is available for free (requires a sign-up process for unlocking).
Image Organizing/ViewingFastStone Image Viewer
|FastStone Image Viewer|