Image Processing Reference
Figure 4.12 The next step is to adjust exposure to set the white values for the image. Start by identifying the critical highlight
area of the image. This is the lightest area that you want to retain image detail.
If you are using Photoshop, using the Color Sampler tool can help with this
adjustment. Select the Color Sampler tool and click the highlight area you want to
maintain. Now, when you adjust the Exposure with the Alt/Option key, the sample
point will be displayed while you make the adjustments so you'll know precisely where
you were trying to keep detail.
Adjustments to the Shadows slider will set the black values for the image. Again
using the Alt/Option key while making the adjustment, move the slider until you have
the blacks set where you want them (Figure 4.13). As with the Exposure control, here
you want to maintain detail in the important shadow area of your image.
Depending on the image and the amount of adjustment made to exposure, the
Brightness slider may not need to be used at all. In Figure 4.14, I've made a small
increase in overall brightness to open the image up a little more. This adjusts the mid-
tones of the image and may or may not be appropriate for the type of image you are
After adjusting the shadows to
set the black values, the image is
beginning to take on a more tra-
ditional black-and-white feel.