Adjustment layer in Photoshop?

Question

How do I keep an adjustment layer from affecting the background base layer?

OR

How to make such an adjustment layer that affects only a particular layer?

Answer 1

Locking the lower layers will not get your problem resolved. It does not stop an adjustment layer from affecting the lower layers, locked or not. Only 2 things you can do. 1 is select the layer you want the effect to be and add the effect without adding an adjustment layer to it. 2nd way is to keep your adjustment layers on a PSD file. Then hide all the other layer besides the one with the adjustment layer. Click on the affected layer to select it, then from the top menu choose
Layer > Merge Visible
or by clicking
Ctrl + Shift + E in Windows
or
Cmd + Shift + E in MACs
Now you'll lose your adjustment layer but keep the affect from it on only the visible layer. Enable visibility on all layers and you'll see that they aren't affected. Now do a save as and rename the document so that you still have your old native file in case you need to go back to it and make additional adjustments. This instruction is for up to Photoshop CS1, CS2 or 3 may have more advanced features. Go to adobe.com site and go to their support and help issues in case you have CS 2 or later version of Photoshop.

Answer 2

You can lock layers fully or partially to protect their contents. For instance, you may want to lock a layer fully when you finish with it. You may want to lock a layer partially if it has the correct transparency and styles, but you are still deciding on positioning. When a layer is locked, a lock icon appears to the right of the layer name. The lock icon is solid when the layer is fully locked and hollow when the layer is partially locked.

To apply lock options to selected layers choose Lock Layers or Lock All Layers In Group from the Layers menu or the Layers palette menu.