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.

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.

Manually correct image perspective and lens flaws

You can apply manual correction alone or use it to refine automatic lens correction.

Adjust the Lens Correction preview and grid

Adjust the preview magnification and grid lines to better judge the necessary amount of correction.

• To change the image preview magnification, use the Zoom tool or the zoom controls in the lower left side of the preview image.
• To move the image in the preview window, select the Hand tool and drag in the image preview.
• To use the grid, select Show Grid at the bottom of the dialog box. Use the Size control to adjust the grid spacing and the Color control to change the color of the grid. You can move the grid to line it up with your image using the Move Grid tool .

Save settings and set camera and lens defaults

You can save the settings in the Lens Correction dialog box to reuse with other images made with the same camera, lens, and focal length. Photoshop saves both Auto Correction settings and Custom settings for distortion, chromatic aberration, and vignetting. Perspective correction settings are not saved because they typically vary from one image to another.

You can save and reuse settings in two ways:

• Manually save and load settings. Set options in the dialog box, and then choose Save Settings from the Settings menu  . To use the saved settings, choose them from the Settings menu. (If you save settings outside the default folder, they don’t appear in the menu; use the Load Settings command to access them.)

• Set a lens default. If your image has EXIF metadata for the camera, lens, focal length, and f‑stop, you can save the current settings as a lens default. To save the settings, click the Set Lens Default button. When you correct an image that matches the camera, lens, focal length, and f‑stop, the Lens Default option becomes available in the Settings menu. This option is not available if your image doesn’t have EXIF metadata.

Reduce image noise and JPEG artifacts

Image noise appears as random extraneous pixels that aren’t part of the image detail. Noise can be caused by photographing with a high ISO setting on a digital camera, underexposure, or shooting in a dark area with a long shutter speed. Low‑end consumer cameras usually exhibit more image noise than high‑end cameras. Scanned images may have image noise caused by the scanning sensor. Often, the film’s grain pattern appears in the scanned image.

Image noise can appear in two forms: luminance (grayscale) noise, which makes an image look grainy or patchy, and color noise, which is usually visible as colored artifacts in the image.

Luminance noise may be more pronounced in one channel of the image, usually the blue channel. You can adjust the noise for each channel separately in Advanced mode. Before opening the filter, examine each channel in your image separately to see if noise is prevalent in one channel. You preserve more image detail by correcting one channel rather than making an overall correction to all channels.