Adjusting Contrast

The contrast of many old photographs diminishes over time because of the instability of the emulsion used to create the print. This emulsion might react chemically with nonarchival photo paper or it might have been exposed to sunlight; both of these can cause discoloring or fading. These problems can usually be remedied by adjusting levels or curves, as long as there is enough detail on the photograph to begin with. Areas of highlight that have washed out will be more difficult to restore, often requiring careful cloning, compositing, or passes with the Burn tool.

Frequently, however, contrast problems are more complex. When a photo has developed a gradual fade from one side to the other, as in Figure 19.13, the problem can be more difficult to fix. You might need to use special masks to apply precision contrast adjustments to the image.

Figure 19.13: An image whose contrast fades from right to left

To get an idea of how these problems might be corrected, try this technique:

1. Open the file gradual_fade.psd from the ch19 folder.

2. Choose Layer ’ New Adjustment Layer ’ Levels. In the New Layer dialog box that appears, click OK. The Levels dialog box appears. Click OK again.

3. Target the Adjustment layer s layer mask by clicking on its thumbnail.

4. Press the D key or click the Foreground and Background icon in the Tool palette to choose black as a foreground color and white as a background color .

5. Choose the Gradient tool . In the Options bar, choose the Linear Gradient icon. Make sure that the Foreground to Background gradient is selected from the Gradient Picker.

6. Click and drag the gradient from right to left. Press the Shift key while dragging to constrain the gradient horizontally.

7. Double-click the Levels 1 Adjustment Layer thumbnail. The Levels dialog box appears.

8. Move the Black Shadow slider to the right until the input level reads 69. Move the Gray Input slider to the right until the midtone input level reads 0.97, which will optimize the contrast on the left side of the image (see Figure 19.14). Click OK.

   
   Figure 19.14: The same image with a levels adjustment applied through the gradient layer mask

9. Repeat steps 2 through 5.

10. Target the layer mask of the Levels 2 layer. Click and drag the gradient from left to right.

11. Click on the Levels Adjustment layer thumbnail. The Levels dialog appears.

12. Move the Black Shadow slider to the right until the input level reads 45. Move the White Input slider to the right until the highlight input level reads 190, which will optimize the contrast on the right side of the image (see Figure 19.15). Click OK.

    
    Figure 19.15: The same image with a levels adjustment applied through the reversed gradient layer mask.

13. Now you ll perform a global contrast adjustment to optimize the contrast of the entire image. Once again, choose Layer ’ New Adjustment Layer ’ Levels. Click OK in the New Layer dialog box. The Layer will be named Layer 3 and will appear above Layer 2 in the stack. This time, move the Black slider to the right until the input level reads 16 and the White slider to the left until the input level reads 238. Click OK.

14. Save the image. Figure 19.16 shows the final result.

Figure 19.16: The completed image with a global levels adjustment applied