1 Select the object with the Pick tool.
2 Click Effects, Color Adjustment, Tone Curve.
3 Choose a color channel from the Channels list box.
4 Enable one of the following:
• Curve — lets you shape the curve by clicking and dragging and smoothes the distribution of values.
• Linear — lets you draw the curve by clicking and dragging but retains straight line segments between nodes.
• Freehand — lets you draw the curve by clicking and dragging.
• Gamma — lets you weigh corrections toward the midtones. If you select Gamma, you must move the Gamma slider to set a gamma curve value.
5 Do any of the following:
• Click the Options button to change the percentage of outlying pixels on either end of the tonal range.
• Click the Smooth button to smooth a freehand curve.
• Click and hold the Smooth button down to continuously smooth the tone curve.
Click the Null button to reset the Tone Curve.
• Click the Horizontal Flip button or the Vertical Flip button to invert the tone curve.
• Press ALT and right-click to change the resolution of the grid.
• Click the Invert button to flip the axis of the graph. 6 Click and drag the tone curve on the grid.
• Response curve files are saved with the extension .CRV
• Enable the Display All check box to view the tone curves for all of the image's channels at once.
• Adjust each channel's response curve separately or simultaneously by working in the composite channel.
You can undo your last action in the Tone Curve dialog box by pressing CTRL + Z.
You can press and hold CTRL to constrain the nodes to a vertical movement.
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