Color and tonal adjustments

Photoshop® CS4 provides a comprehensive set of tools for making color and tonal corrections and adjustments.

• Viewing histograms and pixel values
• Understanding color adjustments
• Adjusting image color and tone
• Targeting images for press
• Matching, replacing, and mixing colors
• Making quick image adjustments
• Applying special color effects to images

 community help (adobe.com)