FACE APPEARANCE SYNTHESIS USING FLEXIBLE APPEARANCE MODEL - 3D Face Processing: Modeling, Analysis and Synthesis - page 93

Figure 8.6. The middle image is the input. The sequence shows a 180° rotation of the lighting
environment.
Figure 8.7 shows four examples of interactive lighting editing by modifying
the spherical harmonics coefficients. For each example, the left image is the
input image and the right image is the result after modifying the lighting. In
example (a), lighting is changed to attach shadow on the person's left face. In
example (b), the light on the person's right face is changed to be more reddish
while the light on her left face becomes slightly more blueish. In (c), the bright
sunlight move from the person's left face to his right face. In (d), we attach
shadow to the person's right face and change the light color as well. Such editing
would be difficult to do with the currently existing tools such as Photoshop TM .
We have also experimented with our technique to relight a person's face to
match the lighting condition on a different person's face image. As we pointed
out in Section 1.2, our method can only be applied to two people with similar skin
colors. In Figure 8.8(a), we relight a female's face shown on the left to match
the lighting condition of a male shown in the middle. The synthesized result
is shown on the right. Notice the darker region on the right face of the middle
image. The synthesized result shows similar lighting effects. Figure 8.8(b)
shows an example of relighting a male's face to a different male. Again, the left
and middle faces are input images. The image on the right is the synthesized
result. From the middle image, we can see that the lighting on his left face is a
lot stronger than the lighting on his right face. We see similar lighting effects
on the synthesized result. In addition, the dark region due to attached shadow
on the right face of the synthesized image closely matches the shadow region
on the right face of the middle image.