Use modifier keys to identify color clipping

When performing adjustments, it’s useful to know if you’re clipping one or more color channels and thereby losing important image details. In Aperture, you can use modifier keys to get instant feedback on channel clipping when using controls in the Exposure and Levels adjustments. Color overlays appear on the image when you press the Command key and drag the sliders to indicate that any, all, or a combination of color channels have been clipped.

The color of the color channel clipping overlay indicates which color channel or combination of color channels are clipped. In addition, Aperture gives you the option of choosing color or monochromatic overlays to indicate clipping.

Figure. Viewer displaying an image with color clipping overlays turned on.

Identify color channel clipping

Press Command while dragging the following sliders:
- Exposure slider (Exposure controls): Shows highlight clipping.
- Recovery slider (Exposure controls): Shows highlight clipping.
- Black Point slider (Exposure controls): Shows shadow clipping.
- Black Levels slider (Levels controls): Shows shadow clipping.
- White Levels slider (Levels controls): Shows highlight clipping.
If one or more color channels are clipped as a result of adjusting one of the above parameters, colored overlays appear over the areas of the image where clipping is occurring. The color of the overlay indicates which color channel is clipped. Release the Command key, and the color overlays disappear.
Note: The color channel clipping overlays appear regardless of whether Highlight Hot & Cold Areas is turned on. For more information, see Show hot and cold areas in your photos.

Set the color channel clipping overlays to color

Choose Aperture > Preferences, and click Advanced.
Choose Color from the Clipping Overlay pop-up menu.

The following table lists the color overlays and the corresponding color channels that have been clipped by the adjustment parameter setting.

Adjustments	Color clipping information
Exposure parameter (Exposure adjustment) Recovery parameter (Exposure adjustment) White Levels parameter (Levels adjustment)	Red: Indicates highlight clipping in the red color channel. Green: Indicates highlight clipping in the green color channel. Blue: Indicates highlight clipping in the blue color channel. Yellow: Indicates highlight clipping in the red and green color channels. Pink: Indicates highlight clipping in the red and blue color channels. Cyan: Indicates highlight clipping in the blue and green color channels. White: Indicates highlight clipping in all three color channels. Black: Indicates no highlight clipping in any color channel.
Black Point parameter (Exposure adjustment) Black Levels parameter (Levels adjustment)	Red: Indicates shadow clipping in the red color channel. Green: Indicates shadow clipping in the green color channel. Blue: Indicates shadow clipping in the blue color channel. Yellow: Indicates shadow clipping in the red and green color channels. Pink: Indicates shadow clipping in the red and blue color channels. Cyan: Indicates shadow clipping in the blue and green color channels. White: Indicates no shadow clipping in any color channel. Black: Indicates shadow clipping in all three color channels.

Adjustments

Color clipping information

Exposure parameter (Exposure adjustment)

Recovery parameter (Exposure adjustment)

White Levels parameter (Levels adjustment)

Red: Indicates highlight clipping in the red color channel.
Green: Indicates highlight clipping in the green color channel.
Blue: Indicates highlight clipping in the blue color channel.
Yellow: Indicates highlight clipping in the red and green color channels.
Pink: Indicates highlight clipping in the red and blue color channels.
Cyan: Indicates highlight clipping in the blue and green color channels.
White: Indicates highlight clipping in all three color channels.
Black: Indicates no highlight clipping in any color channel.

Black Point parameter (Exposure adjustment)

Black Levels parameter (Levels adjustment)

Red: Indicates shadow clipping in the red color channel.
Green: Indicates shadow clipping in the green color channel.
Blue: Indicates shadow clipping in the blue color channel.
Yellow: Indicates shadow clipping in the red and green color channels.
Pink: Indicates shadow clipping in the red and blue color channels.
Cyan: Indicates shadow clipping in the blue and green color channels.
White: Indicates no shadow clipping in any color channel.
Black: Indicates shadow clipping in all three color channels.

Set the color channel clipping overlays to monochrome

Choose Aperture > Preferences, and click Advanced.
Choose Monochrome from the Clipping Overlay pop-up menu.

The following table lists the monochrome overlays and the corresponding color channels that have been clipped by the adjustment parameter setting.

Adjustments	Color clipping information
Exposure parameter (Exposure adjustment) Recovery parameter (Exposure adjustment) White Levels parameter (Levels adjustment)	White: Indicates highlight clipping in all color channels. 66% gray: Indicates highlight clipping in two color channels. 33% gray: Indicates highlight clipping in one color channel. Black: Indicates no highlight clipping in any color channel.
Black Point parameter (Exposure adjustment) Black Levels parameter (Levels adjustment)	White: Indicates no shadow clipping in any color channel. 66% gray: Indicates shadow clipping in one color channel. 33% gray: Indicates shadow clipping in two color channels. Black: Indicates shadow clipping in all three color channels.