One of the things I really like about Aperture is being able to adjust my images while I’m sorting through them. Applying some quick modifications using the Adjustment HUD lets me make better decisions about which images to keep. One adjustment that can be particularly helpful is Highlight/Shadow. Using it can often reveal more detail in the darkest and lightest areas of the picture. Surprisingly quite a few Aperture users aren’t aware of, or using this powerful tool.
Highlight/Shadow is located in the Adjustment HUD right below Levels. By default there are two sliders - one for highlights and one for shadows. These are the Amount sliders and actually I find they often provide a good starting point. However for more control, click the Advanced expansion arrow. Additional sliders for Radius, Color Correction, High and Low Tonal width, and Mid Contrast appear.
Since Highlight/Shadow works by reducing contrast (it makes the darkest darks lighter, and the lightest lights darker) it’s best to apply it only where it’s really needed. So as a matter of habit, I use the minimum tonal width that I can, according to the needs of each image. I often increase the mid tone contrast slightly to compensate for the decrease in contrast at the extremes. The Color Correction slider will increase the saturation of the colors in the tonal values that you are lightening or darkening. I rarely find that I need to adjust the Radius slider, but if the results of the Highlight/Shadow adjustment don’t look natural, try adjusting the Radius slider.
The difference between the original version of this volcano image and the version with a Highlight/Shadow adjustment is pretty impressive. Without being able to see the detail revealed by the Highlight/Shadow adjustment, I probably would have deleted this file.
After Highlight/Shadow Adjustment
Don’t use the Highlight/Shadow adjustment on every image - it’s not a replacement for setting the Exposure or Levels adjustments. But on certain images like this view of the volcano, it can make a huge difference. And the cool part is being able to apply the adjustment so quickly while you’re still sorting through your images.