to display a grid over your image. This tool is useful when fixing alignment in your images. When the grid is not activated, it is gray 
.You can correct barrel and pincushion distortion in digital photographs. In barrel distortion the photo appears to bulge outwards from the center. In pincushion distortion the photo appears to shrink inwards toward the center. Barrel and pincushion distortion are common in photos that were taken with wide angle or zoom lenses.
In ACDSee, you have the option of using manual correction via the Manual Correction slider, or you can enable lens correction via your lens profile. This can be done by selecting the make, model, and lens of the camera used to take your image. The Lens Correction tool can apply automatic adjustments based on the distortion inherent to the lens used, or you can enable lens correction for each image manually. Once a lens profile has been mapped to an EXIF profile, the Make and Model drop-down menus will be pre-populated with the camera used to take the image based on its EXIF information. The Lens Correction tool contains a database of camera makes, models, and their possible lenses. The possible lenses for the selected camera will be available for you to choose from the Lens drop-down menu, unless there is only one possible lens, in which case, that lens will be pre-selected.
You can find the name of the lens used in the EXIF information of your image. However, the lens value displayed in the EXIF may not be reliable in the case of third party lenses as the camera itself may only recognize the third party lens as an ID number. If possible, recover the correct lens value and select it from the Lens drop-down menu.
You can also map the correction specific to your lens, (the lens profile), to your camera make, model, and lens combination. Mapping the lens profile will enable you to apply the correction to all images with the same camera-lens combination that you open in the Develop mode Lens Correction tool, should you choose.
You can use the Manual Correction slider for further adjustments after using automatic correction, or on its own.
You can also use your lens profile to correct chromatic aberration, if it is available.
You can save your settings as a preset for future use.
For quick viewing of the available lens profiles, go here.
To Fix Lens Distortion Using Your Lens Profile:
You can right-click a slider to reset to the default value.
Click the Show Grid button to display a grid over your image. This tool is useful when fixing alignment in your images. When the grid is not activated, it is gray .
To Save Lens Profile as a Default for Future Use:
You can save your camera and lens combination's correction profile and use it as a default for other images taken with the same camera/lens combination. This will ensure that every time you open an image from a particular camera make, model, and lens combination in the Lens Correction tool, the Lens field will be pre-populated with the lens you mapped to that camera. You can also choose to automatically apply this lens profile to other images taken with the same camera/lens combination upon entering Develop mode.
As this function relies on EXIF data, this can mainly be performed with JPEG, DNG, RAW, and TIFF images.
To Manage Your Saved Defaults:
To Fix Chromatic Aberration Using Your Lens Profile:
Chromatic aberration occurs due to the properties of a given lens. Therefore, you can use the lens profile to automatically correct it. The Chromatic Aberration checkbox will be enabled if your selected lens has a corresponding chromatic aberration correction available.
Save your lens profile with the Chromatic Aberration checkbox selected to ensure that chromatic aberration will always be corrected.