White balance an image

If an image has unnatural skin tones or pixels that should be pure white, you can use the White Balance adjustment controls to remove the color cast from the image. Aperture provides three methods for adjusting an image’s white balance:

Balance the warmth of the image based on natural gray.
Balance the warmth of the image based on skin tones.
Balance the image based on traditional color temperature (in degrees kelvin) and tint.

You can adjust an image’s white balance automatically or manually. In most cases, the automatic adjustment succeeds in removing the color cast from the image. You can also use the White Balance eyedropper to choose the natural gray or skin tone pixels that Aperture uses to balance the image. If the Auto White Balance button or the White Balance eyedropper doesn’t completely remove the color cast from the image, you can use the White Balance controls to fine-tune the adjustment.

Although Aperture can set the white balance of the image with great accuracy, sometimes you have to use a combination of these methods to achieve the warm or cool tonality you intended.

Figure. Image before and after a White Balance adjustment.

Adjust an image’s white balance automatically

Select a photo.
In the White Balance area of the Adjustments inspector or the Adjustments pane of the Inspector HUD, click the Auto button.

Aperture evaluates the image. If faces are detected in the image, the image is adjusted to preserve skin tones. If no faces are detected, Aperture identifies a natural gray value in the image and adjusts the image’s white balance based on that value.

To fine-tune the image’s white balance settings after the automatic adjustment has been applied, see “Adjust the color temperature of an image manually,” below.

Adjust an image’s white balance using the White Balance eyedropper

When you have pixels in your image that should be pure white, you can use the White Balance eyedropper tool to automatically set the color temperature and tint of the image.

Select a photo.
In the White Balance area of the Adjustments inspector or the Adjustments pane of the Inspector HUD, specify the method Aperture uses to adjust the image’s white balance by choosing an option from the White Balance pop-up menu.
- To adjust the image’s white balance based on natural gray: Choose Natural Gray.
- To adjust the image’s white balance based on a skin tone: Choose Skin Tone.
- To adjust the image’s white balance based on color temperature (in degrees kelvin) and tint: Choose Temperature & Tint.
Select the White Balance eyedropper tool to activate the Loupe.
The pointer changes to the Loupe, showing a magnified view of the target area. By default, the Loupe is set to magnify the image to 100 percent (full size). If necessary, you can increase the magnification of the Loupe by pressing Shift–Command–Plus Sign (+). For more information, see Loupe overview.
Do one of the following:
- If you chose either Natural Gray or Temperature & Tint from the White Balance pop-up menu: Position the target area of the Loupe over the pixels in the image that are a natural gray, and click.
- If you chose Skin Tone from the White Balance pop-up menu: Position the target area of the Loupe over a skin tone in the image, and click.

The color tonality of the image is shifted either cooler or warmer, depending on the tonality of the original image.

Important: Make sure that there is as little digital noise in the target area of the Loupe as possible. Digital noise can skew the white balance calculation results, introducing a color cast that wasn’t previously there. A simple way to avoid errant pixels is to increase the magnification of the Loupe by pressing Shift–Command–Plus Sign (+).

Adjust the color temperature of an image manually

You can manually adjust an image’s white balance using the Warmth, Temp, and Tint parameter controls.

You use the Warmth and Temp parameter controls to adjust the image’s color temperature. Color temperature is a term used to describe the color of light when the image was shot. However, it refers to the color value of the light rather than its heat value. Light’s color temperature is measured in units called kelvin (K). Adjusting the color temperature of the image changes how Aperture interprets the colors in the image in relation to the assigned temperature of light. The purpose of adjusting the color temperature of an image is to make colors look as natural as possible.

You can manually adjust the tint of an image using the Tint parameter controls. You use the Tint parameter controls when you need to fine-tune the white balance adjustment by neutralizing the remaining green or magenta tint.

Note: The Warmth and Temp parameter controls adjust the image’s color temperature in the same way, except that Aperture doesn’t display the Warmth values in kelvin (K) units.

Select a photo.
In the White Balance area of the Adjustments inspector or the Adjustments pane of the Inspector HUD, specify the method Aperture uses to adjust the image’s white balance by choosing an option from the White Balance pop-up menu.
- To adjust the image’s white balance based on natural gray: Choose Natural Gray.
- To adjust the image’s white balance based on a skin tone: Choose Skin Tone.
- To adjust the image’s white balance based on color temperature (in degrees kelvin) and tint: Choose Temperature & Tint.
Do one of the following:
- If you chose either Natural Gray or Skin Tone from the White Balance pop-up menu: Use the Warmth parameter controls to warm or cool the the image’s tonality.
- If you chose Temperature & Tint from the White Balance pop-up menu: Use the Temp parameter controls to adjust the image’s color temperature (in degrees kelvin) and the Tint parameter controls to neutralize unwanted green or magenta tints.

Tip: You can brush Natural Gray and Skin Tone White Balance adjustments on an image. For more information, see Apply brushed adjustments.