Knowing the exact location of the highest (lightest) and lowest (darkest) values in your image can be very valuable information. It is useful in almost every facet of color workflow management from original capture to final output.For example, it can help you understand how your image will look when: you upload it to your web site... you make an ink jet print... your color lab prints it... your client prints it...
To learn how to quickly find this info in Photoshop click here.
