Removing Lens Casts with the LCC tool

LCC / Correction de l'objectif / Vignettage

Find out how to create a Lens Cast Calibration (LCC) profile using Capture One's LCC tool to remove lens casts from images. The LCC tool can also be used to correct illumination fall-off and create a dust map to automatically remove sensor dust.

Overview Pro

Color casts from lenses are quite a common occurrence on technical cameras. Not only can it occur with wide-angle lenses, it can befall other focal lengths, particularly if extreme shift movements have been applied.

This troublesome effect is caused by the outer image-forming incident rays from the lens striking the surface of the sensor at oblique angles. At worst, it’s highly visible regardless of the scene, however, in its most nuanced form it can only be detected in images with neutral gray or white backgrounds, where typically a green cast can be seen in one corner of the image and a magenta cast in the opposite corner.

It's not just technical cameras that exhibit color casts, the effect is common with rangefinder cameras and other mirrorless models including cameras with non-interchangeable lenses where the rear lens element is positioned close to the sensor, particularly wide-angle lenses.

Reflex cameras, however, rarely exhibit color casts, especially when using fixed (i.e., not zoom or tilt and shift) lenses between 60mm and 120mm focal lengths.

Illumination fall-off in lenses where the corners of the frame darken is even more common across all formats and lens types. Both uneven illumination and lens casts can be corrected in Capture One on supported RAW files using the Lens Cast Calibration (LCC) correction tool. Additionally, the tool can be used to create a dust map to automatically remove sensor dust from images.

Color casts from lenses are quite a common occurrence on technical cameras.

What's a LCC plate?

Made from optical resin, the LCC plate is an opaque, matte textured, spectrally neutral tile that’s included with the Phase One XF value-added kit. It is also available separately as a Phase One accessory (no. #6020094) from your dealer. The 100 x 100mm (4x4 in) plate is suitable for lenses with an accessory thread of approximately up to 95mm.

The plate has a filter factor of 3-4x [1 2/3 to 2 stops]. When adjusting exposure to compensate, you should decrease the shutter speed, as the resultant LCC profile is based on the aperture setting used during capture.

The 100x100mm (4x4 in) the plate is suitable for lenses with an accessory thread of up to 95 mm approximately.

Capturing a characterization image

Capture One's Lens Cast Calibration (LCC) tool requires a "characterization" image to be captured alongside the image to be corrected. Simply capture your image in the studio or on location as normal, followed quickly by a second image with a LCC plate held in the optical path like a filter.

In some specific cases such as when working with a copy stand where you have fixed lighting and short working distances, you can substitute the LCC plate with a gray card. Make sure the card covers the complete field of view and that no part of the resulting image is close to being clipped in the highlights. 

This second characterization image is used later in Capture One to create a LCC reference image and associated LCC profile. The success of the resultant LCC profile is dependent upon the angle of the incident light falling upon the sensor being as close as possible between the characterization image and that of the image you’re trying to correct.

For optimal correction, that means avoiding lighting changes, and not altering lens settings such as focus distance and aperture or applying any tilt and shift movements between the two images.  When more generalized corrections are required, however, Capture One’s LCC tool is still capable of building highly-effective profiles. 

The first step is to capture your image in the studio or on location as normal, followed quickly by a second image with a LCC plate or white perspex tile held in the optical path like a filter.

Quick guide: Six simple steps to correct an image

When left to the default settings, the LCC tool can remove color casts, correct illumination fall-off and map sensor dust.

  1. Following the capture of your image, hold the LCC plate as close as possible over the front of your lens.
  2. Increase your exposure 2-stops, using either the appropriate shutter speed or ISO. (It’s important not to alter the aperture used to capture the initial image.)
  3. Capture an image with the LCC plate in place. (Make sure to cover the lens completely.)
  4. Open the LCC capture (known as the characterization image) in Capture One.
  5. Go to the LCC tool, and click on Create LCC. (The characterization image is corrected and becomes what’s then known as the LCC reference image.)
  6. Select that LCC reference image and the image you would like to apply it to, and choose Adjustments > Apply LCC. The image is updated with the corrections from the LCC reference image.

Add movement data

When attempting to build a LCC profile for a technical camera with movements applied, or a camera with a tilt-shift lens, the profile creation process can be optimized for shift movements.

As lens data is not recorded in the RAW file’s EXIF data from technical cameras, or when using some adapted tilt-shift lenses on mirrorless cameras, the focal length, taking aperture and movement value (in mm) must be manually recorded at the time of capture (using notes or a smartphone).

Shift values should also be recorded when using tilt-shift lenses on DSLRs. For more information on this, see the section on Entering shift movements. These values must be added in the Movement tab of the Lens Correction tool.

  1. Select the appropriate characterization image in the Browser.
  2. Go to the Lens Inspector.
  3. In the Lens Correction tool, go to the Movement tab, verify or manually add the focal length and aperture setting, and manually enter shift X and shift Y adjustments (in mm).

Wide-angle lens correction Pro

Correction can be optimized for wide-angle lenses, particularly those on technical cameras where the outer image-forming rays strike the sensor at acute angles.

  1. Select the characterization image from the Browser, that’s relevant to the image or images you want to correct.
  2. Go to the Lens inspector. Select the LCC panel and press the Create LCC button, or from the Adjustments menu > Create LCC... or press ctrl/right-click and select Create LCC... from the contextual menu. A dialog opens under the main tool bar.
  3. Enable or verify the Include Wide Angle Lens Correction Data option. In general, this can be left enabled, though it will also increase processing time slightly.

Removing sensor dust

When attempting to build a LCC profile from the characterization image, Capture One can map sensor dust for removal. This can be enabled from the LCC panel's Action menu or from an optional dialog window.

When the option is enabled, the data is recorded but it's not automatically applied to the resultant reference image like the other corrections. As sensor dust is usually temporary, if you're going to create a LCC Preset from the reference image, consider whether the dust data is likely to be relevant.

  1. Select the appropriate characterization image in the Browser
  2. Go to the Lens inspector.
  3. From the LCC panel, click on the Action icon (…). The LCC menu opens.
  4. From the menu, select Creating LCC Options and choose Include Dust Removal Information. Alternatively, when ready to create the reference image, click on Create LCC. A warning dialog opens. Verify or enable Include Dust Removal Information.

Verifying display options

If the profile creation dialog doesn’t open after selecting Create LCC, check the options in the LCC panel.

  1. Go to the LCC panel, and click on the action menu icon (…) in the title bar. The LCC Options menu opens.
  2. Select Creating LCC Options… > Don’t show options when creating LCC, and remove a check-mark if present. Once removed, the options will be displayed prior to creating the LCC reference image and associated profile.

Creating a LCC reference image (LCC profile) Pro

Capture One can be used with any RAW supported camera to correct lens color casts and illumination fall-off.

Before you start, you must have captured a characterization image using a LCC plate at the time of capturing the image or images you want to correct.

If you’re attempting to build a profile for a technical camera or a camera with a tilt-shift lens with movements applied, then the profile can be optimized for it. See above for the extra steps involved.

  1. Select the characterization image from the Browser, that’s relevant to the image or images you want to correct.
  2. Go to the Lens inspector. Select the LCC panel and press the Create LCC button, or from the Adjustments menu > Create LCC... or press ctrl/right-click and select Create LCC... from the contextual menu. A dialog opens under the main tool bar, with options for optimizing the profile for wide-angle lenses and for dust mapping. See above for more details.
    • Press Create. The thumbnail in the Browser is now be labeled with LCC.
    • This LCC reference image is now ready to be applied to your image (see below for details), or consider saving as a preset to apply to your images instead. See below for more information.

    Applying LCC correction adjustments

    After the creation of the LCC reference image and the associated LCC profile, you must apply the correction data from them to your images. To speed up your workflow, the correction data is applied between the LCC reference image and the image or images to be corrected.

    If you’ve captured the characterization image with the intent to use it to perform general lens corrections, consider saving the LCC reference image as a LCC Preset. See the section on LCC Presets for more details.

    1. Capture One can detect whether a LCC reference image should be applied to the image next to it in the Browser. If they're not adjacent to each other, select the relevant LCC reference image (i.e., the thumbnail labeled LCC), as well as the corresponding image to be corrected. (A single LCC reference image can be applied simultaneously to multiple images, if they were captured under the same conditions and with identical settings as the LCC reference image.)
    2. From the main menu, select Adjustments > Apply LCC…, or ctrl/right-click, and choose Apply LCC.
    3. The correction adjustments from the profile and any subsequent adjustments to the LCC reference image are applied to the selected image or images and visible in the Viewer. 

    Making manual adjustments

    After applying the LCC reference image to your capture, you can make further adjustments to it from the LCC panel. The adjustments are temporary, and the profile itself is not updated.

    Note that if an option is grayed out the LCC profile was built without that data. You can also adjust the illumination fall-off to taste using the Uniform Light slider.

    If you want to apply the new adjustments to a batch of images, you can use this method on the LCC reference image itself and then re-select the Apply LCC option from the Adjustments menu. However, when you want the adjustments to permanent and repeatable, consider creating a preset or updating the profile instead.

    1. Select the image to be adjusted from the Browser, if not already.
    2. From the Lens inspector, go to the LCC panel.
    3. Enable or disable options as required.
    4. Adjust the Uniform Light slider as necessary.
    5. The image is updated in the Viewer. (Note the LCC profile itself is not updated.)

    Permanently update LCC correction data and profile Pro

    The LCC tool can be used to permanently update the LCC profile associated with the LCC reference image. Use this option to modify or remove shift amounts, disable the Color Cast and Dust Removal options if necessary and permanently update the Uniform Light correction.

    When adjusting the Uniform Light option, the LCC tool doesn't rely on the Uniform Light slider at the bottom of the panel to update the LCC profile. At this stage it has changed functionality from being used to override the amount during profile creation to being a temporary adjustment slider.

    As result, a dialog box opens with a second Uniform Light slider. This is used to override the slider in the LCC tool and update the profile. Like that adjustment slider, corrections range from 0-120%.

    Note that any related presets such as those used within User Styles or User Presets are not updated, therefore you will have to recreate them from the updated LCC reference image.

    1. Select the LCC reference image in the Browser.
    2. Optional. From the Lens Correction tool, click on the Movement tab and update or remove shift values.
    3. From the LCC panel, disable Color Cast/Dust Removal options as appropriate. Options will be grayed-out, if not previously selected.
    4. Click on the action menu icon (...) in the tool's title-bar and select Apply LCC Options... The Uniform Light dialog opens beneath the main tool bar.
    5. Optional. Enable the Uniform Light option box with a check mark and adjust the slider as desired.
    6. Press OK. The LCC profile is updated.
    7. Now when you re-apply the LCC reference image, this new Uniform Light setting and any other changes will override the existing adjustments in the LCC tool.

    Saving LCC correction data as a User Preset Pro

    After capturing a characterization image and creating an LCC profile you can save it and any subsequent manual correction from the LCC panel as a preset.

    Consider using presets if you’ve made a series of characterization images for a particular lens and camera (i.e., sensor) combination, or you have done so with various movements included.

    1. Select the LCC reference image from the Browser, or select an image with the LCC profile already applied to it.
    2. Go to the LCC tool and click on the Manage Preset button (three bars icon) in the title bar. The Manage Preset menu opens.
    3. Select Save User Preset... from the menu. A Save Preset dialog box opens. Disable options as required. Note the profile and correction data can be enabled or disabled separately as desired. In general, it is best to include all the options, as they can be disabled later.
    4. Name and save the preset, ideally using a combination of camera, lens model, f-number and any shift data used during capture. The preset is created and ready to be applied.

    Applying LCC Presets

    The LCC tool can be used to apply presets consisting of not only the LCC profile itself but also of any retrospectively applied adjustments to it.

    The LCC manage menu presents a flat list of available user created LCC presets (i.e., User Presets). A second section in the list displays presets recommended by relevance. This is not meant to be a definitive list.

    Cameras do not record movement data, therefore if the selected image was captured with some movements applied, please verify the LCC preset is suitable, particularly regarding conversion between axes. For more information on the subject, please see the section on Entering shift movements.

    1. Select the image or images you want to apply the preset to. (With multiple images be sure to check they were captured with the same camera, lens (i.e., focal length), taking aperture, and if any movements were included, that they were also the same in each image).
    2. From the LCC tool click on the Manage Presets button (three lines icon) in the title bar. The Manage Presets menu opens.
    3. Select the relevant User Preset from the list. If choosing a recommended preset, be sure to verify that it is suitable for the selected image or images, especially when shift movements have been included in the LCC preset. The list is based on EXIF metadata which does not take shift data into account. Therefore, it may not be the most relevant for the selected image, or images.
    4. Once selected, all selected images are updated with the correction data from the preset. Note that further, manual adjustment using the LCC tool is still possible if desired.