Select the channels palette tab. Drag the RGB channel to the ‘load channel as selection’ symbol (dotted round). This will cause pixels that are 50% gray or brighter to be selected as indicated by the marching ants.
Save the selection by clicking on the ‘save selection as channel’ symbol (rectangle with circle in the middle). This will cause an ‘Alpha 1’ channel to be created.
Click on the RGB channel again to restore the color. Then hit ctrl-D to deselect the marching ants. Note the mask that has been created on the ‘Alpha 1’ channel is already feathered and composed of shades of gray, not an absolute black & white masks as those typically created with the quick mask or magic wand tool.
Now go back and click on the mask (Alpha 1) channel and drag it to the ‘‘load channel as selection’ symbol (dotted round). Then switch to the layers tab and then click on ‘create new fill or adjustment layer’ symbol (circle that is half dark, half white).
You can then select an image adjustment parameter like curves, exposure,
saturation, etc. and make the appropriate adjustment s. The adjustments
will impact the unmasked areas depending on the degree of whiteness
(pure white being the strongest).
You can also select the mask and via the adjustment tool on the
main menu invert it to select the darker areas instead.
All content and images are property of Stephen Fischer Photography, copyright 2009. Last updated: 12/26/2009