Lens Correction
In Gemstone, lens distortion can be managed by using manual correction via the Manual Correction slider, or corrected based on the lens profile by selecting the make, model, and lens of the camera used to take the image.
The Lens Correction filter contains a database of camera makes, models, and their possible lenses. The possible lenses for the selected camera will be available to choose from the Lens drop-down menu, unless there is only one possible lens, in which case, that lens will be pre-selected.
The name of the lens used to take the photo can be found in the Current Lens Information section.
The lens profile can also be used to correct chromatic aberration, if it is available.
Use the Manual Correction slider for further adjustments after using automatic correction, or on its own.
For quick viewing of the available lens profiles, go here.
To fix lens distortion using lens profile:
- Select Filter | Geometry | Lens Correction.from the main menu, or press Ctrl + Shift + C.
- In the Lens Correction dialog, enable the Enable Lens Profile checkbox.
- If the displayed camera make and model are not correct, select the correct options from the Make and Model drop-down menus.
- From the Lens drop-down menu, select the lens used to take the image. This information is displayed in the Current Lens Information section. The correction will occur automatically.
- To make further adjustments, move the Strength slider in the Manual Correction section to the left for a bulge effect, or to the right to stretch the edges of the image.
Right-click a slider to reset to the default value.
Enable the Show Grid checkbox to display a grid over the image, useful for fixing alignment issues in an image.
To fix chromatic aberration using lens profile:
Chromatic aberration occurs due to the properties of a given lens. Therefore, use the lens profile to automatically correct it. The Chromatic Aberration checkbox will be enabled if the selected lens has a corresponding chromatic aberration correction available.
- Select Filter | Geometry | Lens Correction from the main menu, or press Ctrl + Shift + C.
- Enable the Enable Lens Profile checkbox.
- Enable the Chromatic Aberration checkbox.
To fill-in the edges of a manually corrected image:
Some manual adjustments may affect the edges of the image. Choose the color to be used to fill the discrepancies created by the lens correction. Alternatively, opt for transparency in the fill-in area by enabling the Transparency checkbox.