| In that case JenJen, you needn't worry about linking them at all - just stick another adjustment layer on top.
Imagine you've got a picture, and on top of that you lay a slightly opaque sheet of acetate (your levels layer), and then on top of that you lay a red tinged transparent sheet of acetate (your colour balance layer). You can still see the picture underneath, and if you remove one or both of the adjustment layers, the effect changes.
That's what you're accomplishing by using layers. All adjustment layers are 'transparent' - the effects filter on down through so you can see the picture underneath with the adjustments you've made.
When you flatten (or merge down) all the layers, the adjustments get calculated and made to the picture itself. It is therefore better to use multiple adjustment layers, and just flatten once (thereby only altering the data once), rather than make changes, flatten, make more changes, flatten again. |