Operation Manual

170
USING PHOTOSHOP
Retouching and transforming
Last updated 12/5/2011
More Help topics
Select a preset brush” on page 299
Correcting image distortion and noise
About lens distortion
Barrel distortion is a lens defect that causes straight lines to bow out toward the edges of the image. Pincushion
distortion is the opposite effect, where straight lines bend inward.
Examples of barrel distortion (left) and pincushion distortion (right)
Vignetting is a defect that darkens the corners of an image due to light falloff around the perimeter of the lens.
Chromatic aberration appears as a color fringe along the edges of objects, caused by the lens focusing on different
colors of light in different planes.
Some lenses exhibit different defects at certain focal lengths, f-stops, and focus distances. With the Lens Correction
filter, you can specify the combination of settings used to make the image.
Correct lens distortion and adjust perspective
The Lens Correction filter fixes common lens flaws such as barrel and pincushion distortion, vignetting, and
chromatic aberration. The filter works only with 8- and 16-bit-per-channel images in RGB or Grayscale mode.
You can also use the filter to rotate an image or fix image perspective caused by vertical or horizontal camera tilt. The
filter’s image grid makes these adjustments easier and more accurate than using the Transform command.
Automatically correct image perspective and lens flaws
Using lens profiles, the default Auto Correction option quickly and accurately fixes distortion. For proper automatic
correction, Photoshop requires Exif metadata that identifies the camera and lens that created the image, and a
matching lens profile on your system.
1 Choose Filter > Lens Correction.
2 Set the following options:
Correction Select the problems you want to fix. If corrections undesirably extend or contract the image beyond
original dimensions, select Auto Scale Image.
The Edge menu specifies how to handle blank areas that result from pincushion, rotation, or perspective corrections.
You can fill blank areas with transparency or a color, or you can extend the edge pixels of the image.