Image Processing Reference
In-Depth Information
Original luma
Corrected luma
Note loss of information
Figure 35-2 Brightness correction.
showing the measurements for a video picture containing a female face that almost
fills the screen. The skin tone is set correctly and the exposure, luma, and contrast are all
Once the black level is set correctly, use the contrast control to open up the range of
values to pull the white level up to an optimal setting.
Be careful with the contrast setting. Too much contrast enhancement causes crush-
ing. Figure 35-5 is a screen shot of the vector scope for the same picture but shows the
effect of a gross over-adjustment of the contrast. In this picture, the skin tone is all washed
out to white.
Figure 35-3 Photoshop's levels palette.
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