Curves
When you select the Curves button, a dialog box appears that allows you to adjust the midtones of the image without losing detail in the lightest and darkest areas.
Select the Curve or Line button, depending on whether you want a curved or an angled setting. Place the mouse cursor over the line, click the left mouse button, and drag the line to set the curve you want.
Adjusting the curve up (1) or down (2) turns the image brighter or darker respectively.
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