3. Adjust the tonal range.

Begin tonal corrections by adjusting the values of the extreme highlight and shadow pixels in the image, setting an overall tonal range that allows for the sharpest detail possible throughout the image. This process is known as setting the highlights and shadows or setting the white and black points.

Setting the highlights and shadows typically redistributes the midtone pixels appropriately. When pixel values are concentrated at either end of the tonal range, however, you may need to adjust your midtones manually. It is not usually necessary to adjust midtones in images that already have a concentrated amount of midtone detail.

There are several different ways to set an image's tonal range:

• You can drag sliders along the histogram in the Levels dialog box. (See Using Levels to set highlights, shadows, and midtones.)
• (Photoshop) You can adjust the shape of the graph in the Curves dialog box. This method lets you adjust any point along a 0-255 tonal scale and provides the greatest control over an image's tonal quality. For more information, see Using the Curves dialog box (Photoshop).
• (Photoshop) You can assign target values to the highlight and shadow pixels using either the Levels or Curves dialog box. This can be a useful method for images intended for printing on a press. For more information, see Using target values to set highlights and shadows (Photoshop).