Correcting Tone and Exposure - Beginning Photo Retouching and Restoration Using GIMP - page 56

Figure 3-23. Finding the black point of an image

5. Lower the opacity of both the White Point and Black Point layers to about 50%,

so that the image is partially visible and both the black and white reference areas
are visible (Figure 3-24 ).

Figure 3-24. Lower the opacity of the layers, to see where to place the eyedroppers

6. Click the Contrast Adjustment layer, to make it active, and open the Levels dialog

box (Image Menu ➤ Colors ➤ Levels). Use the black eyedropper to click the
black point indicated by the Black Point layer. Repeat the same step with the
white eyedropper on the white point. Do not click OK yet; keep the Levels dialog
box open! Hide the Black and White Point layers at this point.

7. Now, adjust the midpoint slider slightly to the left, until the value is about 128,

then click OK (Figure 3-25 ).