Adobe Photoshop CS4 - Manual (Page 177)

170 USING PHOTOSHOP CS4
Color and tonal adjustments
Last updated 1/10/2010
• Choose Layer > New Adjustment Layer > Curves. Click OK in the New Layer dialog box.
Note: You can also choose Image > Adjustments > Curves. But keep in mind that this method makes direct adjustments
to the image layer and discards image information.
2 (Optional) To adjust the color balance of the image, choose the channel or channels that you want to adjust from
the Channel menu.
3 (Optional) To edit a combination of color channels at the same time, Shift-click the channels in the Channels panel
before choosing Curves. The Channel menu then displays the abbreviations for the target channels—for example,
CM for cyan and magenta. It also contains the individual channels for the selected combination. This method does
not work in a Curves adjustment layer.
Note: select Channel Overlays in Curve Display Options to see the color channel curves superimposed on the composite
curve.
4 Add a point along the curve by doing one of the following:
• Click directly on the curve.
• Select the On-image adjustment tool , then click the area in the image that you want to adjust. Drag the pointer
up or down to lighten or darken the values for all similar tones in the photo.
To identify areas in the image that are being clipped (black or white), select Show Clipping in the Curves dialog box
or Show Clipping For Black/White Points from the Adjustments panel menu.
You can add up to 14 control points to the curve. To remove a control point, drag it off the graph, select it and press
Delete, or Ctrl-click (Windows) or Command-click (Mac
OS) it. You cannot delete the endpoints of the curve.
With the On-image adjustment tool selected, click three areas of an image to add points to the curve. Increased image contrast resulting from
lightening the highlights and darkening displayed by an S-curve.
To determine the lightest and darkest areas in an RGB image, drag across the image with the On-image adjustment
tool. The Curves graph displays the intensity values of the area under the pointer, and the corresponding location on
the curve. Dragging the pointer across a CMYK image shows the percentages in the Color panel, if it’s set to display CMYK
values.
5 Do one of the following to adjust the shape of the curve:
• Click a point, and drag the curve until the tone and color look correct. Shift-click to select multiple points and move
them at once.