Lab Color mode

In Photoshop, the Lab Color mode has a lightness component (L) that can range from 0 to 100. In the Adobe Color Picker, the a component (green-red axis) and the b component (blue-yellow axis) can range from +127 to -128. In the Color palette, the a component and the b component can range from +120 to -120.

You can use Lab mode to work with Photo CD images, edit the luminance and the color values in an image independently, move images between systems, and print to PostScript Level 2 and Level 3 printers. To print Lab images to other color PostScript devices, convert to CMYK first.

Lab images can be saved in Photoshop, Photoshop EPS, Large Document Format (PSB), PDF, Photoshop Raw, TIFF, Photoshop DCS 1.0, or Photoshop DCS 2.0 formats. 48-bit (16 bits per channel) Lab images can be saved in Photoshop, Large Document Format (PSB), Photoshop PDF, Photoshop Raw, or TIFF formats.

Note: The DCS 1.0 and DCS 2.0 formats convert the file to CMYK when opened.

Lab color is the intermediate color model Photoshop uses when converting from one color mode to another.