Clive R. Haynes FRPS
this to yourself by opening an image, then via the Image > Adjust > Brightness/Contrast
route, radically alter the brightness and the contrast and note the position of
the two slider controls.
Open the Brightness/Contrast adjustment again. Note the position of the two 'sliders' - they've reset to zero! This, then, is the new starting point. Now, try by adjusting the sliders to restore the image to how it was before - hmmm, not possible I think you'll agree.
splendid it would be if we could return to the point at which we left the sliders
and alter/restore from that point. Good news!
Making an Adjustment Layer will give you complete control over the following:
Creating an Adjustment Layer.
At the base of the Layers palette, click on the half black / half white circle icon
From the list that appears, choose (in this instance) Brightness/Contrast.
The Adjustment Layer appears above the Layer you had activated.
Note: as the Adjustment Layer is above the lower layer(s) it will affect all Layers beneath.
Now, to prove the advantage of the Adjustment Layer, follow the experiment below.
Radically alter the position of the two (Brightness/Contrast) sliders.
Return to the Adjustment Layer by double clicking on it or via Layer > Adjustment Options - this time you'll see that the sliders are where you left them set. They are available to be adjusted again. This wonderful facility exists for all the 'Types' named in the Adjustment Layer dialogue box drop-down list.
You can have several different Adjustment Layers running, all controlling different settings if you wish.
Adjustment Layer 'Mask' Facility
the Layer Mask within the Adjustment Layer
Making a Selective Adjustment Layer
you wish to adjust a specific area within the image, you can do this by making
a 'selection' in one of the usual ways ('inverse' it if you need) then creating
an Adjustment Layer.