New Post: LAB image - adjusting levels like photoshop

Hello,

i know there´s an option to adjust the levels, but i can not find a manual how to do it for a LAB 16Bit image. In photoshop i have the following dialogue:



And i can adjust the L, A and B channel.

I am looking just for a short example, how can i control the LAB channels, for an RGB is clear, but i did not find the code for an LAB image. Thanks in advance.