I want to know the lab values of a simple document filled completely with a single color, is that possible using Adobe Photoshop CS2, if yes then please let me know how we do it?
That should be fairly easy. Does the document have an embedded ICC profile? Ideally it would have a working space profile like sRGB or AdobeRGB embedded in it so that it can define what Lab values your document should have.
In CS2, there is a color pallet on the right side of the screen. If you click the arrowhead on the upper right corner it will give you a choice about which colors you wish displayed. Choose Lab, and use your eye dropper to sample the single color in your document. The Color pallet will show the Lab values.
It is critical that you know what profile is associated with this document. If there is no profile embedded there, then these Lab values are calculated using the default profiles in your Color Settings dialog box. For example, if you have a simple RGB image, untagged with any profile, then the color on your document is interpreted through the RGB working space profile that is listed in Color Settings. If sRGB for example, then that is the profile that is interpreting these Lab values for you.
Thanks you so much for helping me out Patrick Herold, this helped me a lot