Levels <Ctrl+L>

You can view the color distribution (Histogram) for each channel that composes the photo colors and adjust the level to compensate for the color and brightness of a photo. You can adjust the level for each channel to adjust the color of a photo properly.

Steps

To adjust color level

Open the photo you want to adjust the color level.
Click Color > Levels.
In the Level dialog box, select RGB from Channel.
Enter the values in Input Level and Output Level or move the control pointer to specify each value.
Click OK.

More Information

Level Dialog Box

Channel

Input Level: Adjust the level range and the gamma value to be used for the selected channel. To select the range (extreme values – 0. 255) enter the gamma value (median – 1.0) in the box or drag the wedge shaped mark appearing below the Histogram. All the levels below the minimum [Input Level] will be set to the minimum [Output Level]. Likewise, all levels above the max [Input Level] are set to the max [Output Level]. You can adjust the gamma value to adjust the brightness. If the gamma value is greater than 1.0, then the photo will become brighter, and if it is less than 1.0, it will become darker.
Output Level: Set the levels for the brightest and the darkest areas in a photo. This is used to reduce the amount of ink consumed for the dark areas of a photo printed, published and so on.

Option Button

The Auto Color Option dialog box appears.

Auto Color Option Dialog Box

Shadows

You can adjust the color on the darkest of the photo. The larger the value, the stronger the effect and the more the image quality is damaged.

Highlights

You can adjust the color on the brightest of the photo. The larger the value, the stronger the effect and the more the image quality is damaged.

Save as Default

You can save the current settings to apply to other photos that you will work on. The larger the value, the stronger the effect and the more the image quality is damaged.