8 Replies Latest reply on Mar 30, 2017 3:28 AM by c.pfaffenbichler

    What does the Lab color values in Photoshop mean?

    sharons73627271 Level 1

      I am using Adobe Photoshop CS6 in a Windows 7 environment. I am familiar with the L*a*b* color system and color values as, for example, described here Understanding Photoshop color modes

       

      I just opened a photo in RAW format in Photoshop and chose Image > Mode > Lab Color. I looked at the Histogram for each color channel and it does not show the values I expected. For example:

      Lightness has a mean value of 109.61 > not between 0 and 100

      a has a mean value of 130.67 > not between -128 and 128

      b has a mean value of 140.98 > not between -128 and 128.

       

      So my questions: What does these values mean and why are they not within the expected range? How are the values calculated? Is there any way to convert the values to the expected range?