Camera lenses can create distortions in photographs. You see these distortions most often in wide-angle photographs, in close-up photographs taken with cameras with fixed focal ranges, and in cameras with inexpensive lenses (such as disposable cameras).
Important: These effects work on greyscale and 16 million color (24-bit) images only. To increase the color depth of an image, see Increasing the Color Depth of an Image.
Types of Lens Distortions:
Barrel distortion If your image has a barrel distortion, it looks pushed out at the center. Lines that should be straight are curved. You must correct lens distortions before cropping the image. For distortion corrections to work properly, the axis of the camera lens must coincide with the center of the image. See Correcting Barrel Distortions.
Fisheye distortion If your image has a fisheye distortion, it looks as though it has been pasted onto a sphere or blown up like a balloon. Lines that should be straight are curved and the edges of the image look compressed. See Correcting Fisheye Distortions
Pincushion distortion If your image has a pincushion distortion, it looks pushed in at the center. Lines that should be straight are curved. See Correcting Pincushion Distortions.
Basic Steps in Improving Photographs
How to Approach Color, Contrast, and Saturation Adjustments
Common Problems and How to Solve Them
Removing Image Defects and Noise