Working with the Exposure Controls

You use the Exposure adjustment controls to set the exposure, recovery, black point, and brightness values.

Using the Auto Exposure Button

When you want to quickly adjust the exposure of a RAW image, you can use the Auto Exposure button. Depending on the exposure Aperture sets for the image, you can always fine-tune the image’s exposure setting using the Exposure adjustment controls. For more information about manually adjusting the exposure of an image, see Correcting Exposure in the Image.

Figure. Image before and after an Auto Exposure adjustment.

Note: Automatic exposure adjustment is available for Aperture-supported RAW images only. If you want to adjust the exposure of another file type, such as JPEG or TIFF, see Working with the Exposure Controls. For a list of supported RAW file types, go to the Apple website at http://www.apple.com/aperture/specs.

To automatically correct the exposure of a RAW image
  1. Select an image.

  2. In the Exposure area of the Adjustments inspector or the Adjustments pane of the Inspector HUD, click the Auto Exposure button.

    Figure. Auto Exposure button in the Adjustments inspector.

The exposure of the image is automatically corrected. If you need to fine-tune the image’s exposure setting, see Correcting Exposure in the Image.

Correcting Exposure in the Image

If you’ve over- or underexposed an image, you can correct it by adjusting the Exposure parameter. The amount of latitude you have—the visually acceptable range of f-stops—depends on the file type and the bit depth of the image. Typically, a RAW file is capable of a slightly wider latitude than a JPEG file.

Figure. Image before and after an Exposure adjustment.

Note: The amount of latitude depends on the camera, the bit depth, the file format, and the amount of compression applied during capture. For optimum results, you should shoot your images within 1.5 stops of a balanced exposure.

To correct the exposure of an image
  1. Select an image.

  2. In the Exposure area of the Adjustments inspector or the Adjustments pane of the Inspector HUD, adjust the Exposure parameter by doing one of the following:

    • Drag the Exposure slider.

    • Click the left or right arrow in the Exposure value slider to change the exposure of the image by 5 percent increments, or drag in the value field.

    • Double-click the number in the Exposure value slider, then enter a value from –9.99 to 9.99 stops and press Return.

      Figure. Exposure controls in the Exposure area of the Adjustments inspector.

    A negative value decreases the exposure (darkening the image), and a positive value increases the exposure (lightening the image).

The exposure of the image is updated as you change the parameter value.

Recovering Highlight Details in the Image

Many images, especially RAW image files, have additional highlight detail that isn’t displayed by default. Aperture provides the Recovery parameter controls to give you access to that additional headroom. Because digital image sensors differ from camera model to camera model, the highlight headroom varies. In some cases, you can recover significant detail that appears lost or blown out in the most extreme highlight areas of the image.

Note: The Recovery controls are not available for RAW decoding versions 1.0 and 1.1. To make the Recovery controls available, reprocess the image. For more information, see Working with the RAW Fine Tuning Controls.

To recover highlight details in the image
  1. Select an image.

  2. In the Exposure area of the Adjustments inspector or the Adjustments pane of the Inspector HUD, adjust the Recovery parameter by doing one of the following:

    • Drag the Recovery slider.

    • Click the left or right arrow in the Recovery value slider to change the amount of highlight detail to recover in the image by 5 percent increments, or drag in the value field.

    • Double-click the number in the Recovery value slider, then enter a value from 0.0 to 1.5 and press Return.

      Figure. Recovery controls in the Exposure area of the Adjustments inspector.

    The higher the value, the more highlight information is made available, and the more highlight detail is recovered.

The image’s highlights are updated as you change the parameter value.

Setting the Image’s Blacks

Shadow detail and the importance of visual elements in shadow vary from image to image. In addition, some cameras are more capable of capturing shadow details than others. In some photos, such as an image of a person’s face in the shadow of an alley, the shadow is the most important visual element in the image. In other images, the details in the shadows have nothing to do with the main subject of the image. For example, the shadow area of the image may obscure trash that would otherwise ruin a pristine image. In Aperture, you use the Black Point parameter controls to increase the threshold of shadow details in the image as well as crush the blacks when necessary.

Note: The Black Point controls are not available for RAW decoding versions 1.0 and 1.1. To make the Black Point controls available, reprocess the image. For more information, see Working with the RAW Fine Tuning Controls.

To set the black point of the image
  1. Select an image.

  2. In the Exposure area of the Adjustments inspector or the Adjustments pane of the Inspector HUD, adjust the Black Point parameter by doing one of the following:

    • Drag the Black Point slider.

    • Click the left or right arrow in the Black Point value slider to change the shadow detail to recover in the image by 5 percent increments, or drag in the value field.

    • Double-click the number in the Black Point value slider, then enter a value from –5.0 to 50.0 and press Return.

      Figure. Black Point controls in the Exposure area of the Adjustments inspector.

    Decreasing the value increases the amount of detail in the shadow areas by moving pure black below the current black point. Increasing the value decreases the amount of detail in the shadow areas of the image, effectively crushing the blacks by moving pure black above the current black point.

The image’s black point is updated as you change the parameter value.

Adjusting Brightness in the Image

You can adjust the Brightness parameter when you want to lighten or darken your image. When you adjust brightness, the brightness values of the midtone pixels in the image change the most. You can change the brightness of the image temporarily to see how the adjustment affects details in the shadows, midtones, and highlights. For more precise control over the range of tonality in the image, consider using the Levels adjustment controls. For more information about adjusting levels, see Working with the Levels Controls.

Figure. Image before and after a Brightness adjustment.
To adjust brightness in an image
  1. Select an image.

  2. In the Exposure area of the Adjustments inspector or the Adjustments pane of the Inspector HUD, adjust the Brightness parameter by doing one of the following:

    • Drag the Brightness slider.

    • Click the left or right arrow in the Brightness value slider to change the brightness of the image by 5 percent increments, or drag in the value field.

    • Double-click the number in the Brightness value slider, then enter a value from –2.0 to 2.0 and press Return.

      Figure. Brightness controls in the Exposure area of the Adjustments inspector.

A value below 0.0 decreases the brightness of the image. A value greater than 0.0 increases the brightness of the image. The brightness of the image is updated as you change the parameter value.