As with most of Photoshop's features and tools, there are several ways to accomplish the same task. It is a matter of personal preference as to which method you use.
This basic Photoshop tutorial instructs on color correction using Adobe Photoshop's hue/saturation and curves to correct color casts that are created from improper white-balance setting in the camera, or unusual lighting conditions which overwhelm the natural color of a scene.
Darkening a Selective Area of the Photo
To darken a single area of your photograph, duplicate the background layer by typing Command>J, or create a "Curve Adjustment Layer" by scrolling to "Curves" on the "Adjustment Layer" icon located at the bottom of the Layers Pallet window (black & white circle icon). Do not make any adjustments with curves.
Set the new adjustment layer to the "Screen" mode in the Layers Pallet window's pull-down menu, and adjust its opacity to between 25% and 50% depending on the amount of correction.
Tip: Use the "Control" key to bring up the "Brushes Pallet" window, or use the left and right "Bracket" keys to increase or decrease brush size.
Using the Eraser Tool (E), set the brush opacity to a lower percentage (around 50%), and select pure white as your brush color, then slowly paint the area that you would like to brighten.
Technical Note: You can reverse the entire process (darken instead of lighten) by setting the "Curve Adjustment Layer" to multiply instead of "Screen," then follow all of the steps above using the "Brush Tool" (B) instead of the "Eraser Tool" (E).
Lightening a Selective Area of the Photo
To brighten a single area of your photo, duplicate the background layer by typing Command>J, or create a "Curve Adjustment Layer" by scrolling to "Curves" on the "Adjustment Layer" icon located at the bottom of the Layers Pallet window (black & white circle icon). Do not make any adjustments with curves.
Set the layer to the "Screen" mode, and adjust the opacity to around 25% to 50%. Invert the layer by typing Command>I, or scroll from Image>Adjustments>Invert on the top menu-bar. Using the "Brush Tool" (B), set the Brush opacity to a lower percentage (around 50%), and select pure white as your brush color, then slowly paint the area that you would like to brighten.
Technical Note: You can reverse the entire process (darken instead of lighten) by setting the "Curve Adjustment Layer" to multiply instead of "Screen," then follow all of the steps above using the "Eraser Tool" (E) instead of the "Brush Tool" (B).
Global Adjustments in Photo Exposure
A new feature to CS3 is the ability to make camera-setting-like changes to an image using an "Exposure Adjustment Layer" by scrolling to "Exposure" on the "Adjustment Layer" icon's pull-down menu located at the bottom of the Layers Pallet window. In the Exposure pallet window you can adjust "Exposure" which will globally lighten or darken the image, "Offset" which will make adjustments to the shadow and/or highlight areas, and "Gamma Correction" will effect the contrast by ramping up the shadow/highlight difference.
Technical Note: Once you have made the appropriate adjustments, you can de-tune the opacity of the adjustment layer to soften the effect.
Global Adjustments in Lighting
To make global adjustments to the overall contrast of the image, and to selectively adjust the highlight and shadow areas of the photo using CS3, you would convert the background layer into a "Smart Object" by scrolling from Layer>Smart Objects>Convert to Smart Object.
The next step is to scroll from Image>Adjustments>Shadow/Highlight on the top menu bar, and adjust the sliders accordingly to open up shadow areas or reduce brightness in the highlight areas.
