The DEPTH Workflow - 3D Postproduction: Stereoscopic Workflows and Techniques - page 153

The 3D Crop-and-Scale

As we discussed in Chapter 1 , the L and R images in an image pair overlap. Since
the experience of 3D depends on each eye receiving a slightly different image,
we have a problem. There are portions of the image pairs that are “matted” or
“cropped” out because they only contain information for one eye (Figure 5.10) .
This crop is performed automatically by your depth tool. Most depth tools have the
option of stretching edge pixels on L and/or R to cover missing image information
in areas of the frames (edges) that are typically outside of the area of interest.

Non-overlapped portions of imagery are by dei nition 2D and thus fail to create a
3D experience in that portion of the frame. These unusable portions of imagery
are matted or cropped out by the imaging system or in postproduction and
only the overlapping portions of the imagery are preserved by blowing up the
imagery in the frame. The problem is losing overall image resolution from unusable
pixels (unusable in a 3D sense) as the remaining (overlapped) portions of the
image are “blown up” to i ll the frame. An additional option is to work with

CROP

UNUSABLE (2D)
PORTIONS OF L
AND RARE
CROPPED OUT

SCALE

CROPPED LAND R
ARE BLOWN UP

Figure 5.10 3D Crop & Scale.