Mastering Adobe Photoshop CS requires skill in many diverse areas. While modifying an image's color, enhancing an old photograph, removing dust and scratches, may require different skills, they have one common thread — selection.

When you select an area of a Photoshop document, the selection becomes the work area — filters, adjustments, and brushes will only work within the selection boundary. Photoshop gives you many ways to create your desired selection.

In addition, Photoshop gives you ways to select areas based on color, and then fill those areas with any color you choose. Photoshop lets you use industry-standard color sets, or you can create and save your own customized color palettes.

It's also important to understand how Photoshop manages color information and that's where the Channels palette comes into the picture. Channels are where color information is stored.

In addition, you can use various commands, adjustments, and photo filter and shadow and highlight adjustments to fine tune an image.