There are two approaches to sampling colors from images in Illustrator and/or Photoshop: using the eye dropper and color sampler or saving the color table via Save for Web option. The former samples a single color at a time from a specific location, the latter, samples a series of colors from the entire image.

This new plug-in for Illustrator and Photoshop helps you discover beautiful color palettes by importing an image (e.g., Evgeny Kiselev’s incredible Furycane) into the panel and sampling colors along points of a line that you draw over the image. This approach allows you to define specific areas of the image in order to capture the best color combinations. These colors can be saved to Illustrator or Photoshop’s Swatches panel. Additional features include changing the amount of colors sampled and sorting based on Hue, Saturation or Brightness. Colors are also saved in the same color mode (CMYK or RGB) relative to the current file.

For more information: http://blog.drwoohoo.com/color-lifter/