Page 171 - DCAP303_MULTIMEDIA_SYSTEMS

Unit 10: 3D Modelling and Animation Tools

notes
figure 10.2: the original Car is on the right

image orientation

Image editors are capable of altering an image to be rotated in any direction and to any degree.
Mirror images can be created and images can be horizontally flipped or vertically flopped. A small
rotation of several degrees is often enough to level the horizon, correct verticality (of a building,
for example), or both. Rotated images usually require cropping afterwards, in order to remove
the resulting gaps at the image edges.
figure 10.3: image orientation (from left to right): original, -30° CCW rotation, and flipped

perspective Control and Distortion
Some image editors allow the user to distort (or “transform”) the shape of an image. While
this might also be useful for special effects, it is the preferred method of correcting the typical
perspective distortion which results from photographs being taken at an oblique angle to a
rectilinear subject. Care is needed while performing this task, as the image is reprocessed using
interpolation of adjacent pixels, which may reduce overall image definition. The effect mimics
the use of a perspective control lens, which achieves a similar correction in-camera without loss
of definition.

figure 10.4: perspective Control: original (left), perspective Distortion removed (right)

Lens Correction

Photo manipulation packages have functions to correct images for various lens distortions
including pincushion, fisheye and barrel distortions. The corrections are in most cases subtle, but
can improve the appearance of some photographs.

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