The three colorspace which are most well-known are R.G.B., C.M.Y.K., and Grayscale. These three colorspaces are practical and real-world. Any changes made in intermediate steps immediately affect the item being edited, so that early steps place limitations on later steps. In addition to this in R.G.B. any change in lightness or darkness has an immediate affect upon color content as well.
But what if no changes were made until the final step and what if changes in lightness and darkness had no affect upon color content until the final step.
This is only possible in a colorspace that is theoretical and algorithmic based. Just as in algebra, there are imaginary numbers based on the square root of -1, so also in this theoretical colorspace there would be "colors" which were self-contradictory.
This is the L.A.B. colorspace. In this colorspace, the L channel controls lightness and darkness, while the alpha and beta channels define color content. A picture is imported into the colorspace. Various changes are made to the mathematical definitions of the content of the photograph. Then the final step is exporting the product to a real world colorspace.
In the picture below the original is from the Yellowstone National Park Service and is in the public domain. The picture on the right has been edited in the L.A.B. colorspace. The changes made to this photo were made throughout the photo. Any exclusions were defined by color and/or lightness value not by what area of the photo was affected.