- What is a lens profile?
- A lens profile describes the types of optical aberrations that exist in a particular lens and prescribes how to correct the lens distortions in an image captured from the same lens.
- What is Adobe® Lens Profile Creator?
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Lens Profile Creator is a free utility that enables the easy creation of lens profiles for use in the Adobe Photoshop® family of products, such as Adobe Photoshop CS5, Adobe Camera Raw® and Adobe Photoshop Lightroom®.
- Who should try Lens Profile Creator?
- Lens Profile Creator is great for photographers at any level who’d like to create a custom lens profile for their own lens.
- Which platforms are supported?
- The Lens Profile Creator is provided for both Macintosh and Windows platforms.
- Where can I post issues and comments?
- Please use the Labs forum for Lens Profile Creator to ask questions and post issues/comments.
- Why shoot nine images, filling up the frame at different angles per shot, when I can shoot one image with the chart filling up the entire frame at once?
- Lens Profile Creator employs the state-of-the-art multi-view image geometry algorithm to estimate all the camera model parameters, such as the principal point (image center), focal length, and distortion parameters. It requires a minimum of three images of the checkerboard. We recommend shooting nine images instead of the minimum three because it would permit the use of a smaller checkerboard to sample data points closer to the edges of the image frame where the lens aberration are typically more pronounced, and provide fallback images if for some reason the Lens Profile Creator fails to process all the images successfully. In general, additional images will improve the robustness and the accuracy of the camera model parameter estimates.
The multi-view image calibration setup utilized by the Lens Profile Creator also eliminates the need of an expensive and controlled studio setup, making the technology more accessible to ordinary photographers. In this new setup, the camera and the calibration chart no longer need to be meticulously aligned, or the chart to be uniformly illuminated. There is no need to have a single chart to fill the entire field-of-view of the camera, which is difficult to do for wide-angle or fisheye lenses. - Should more than nine images be shot when using a wide angle or fisheye lens that requires a greater number of images to overlap the entire image frame?
- Choose a number of images to shoot so that, when grouped together, the chart images cover every part of the image frame. For wide-angle or fisheye lenses or for cases where you’re shooting a chart further away that takes up less of the image frame per shot, it’s recommended to shoot more than nine images.
- Does the chart plane have to be completely parallel to the plane of the image sensor in the camera for all the chart images?
- No. Lens Profile Creator actually expects camera orientation and location with respect to the chart changes from one image view to the next. It is recommended that one of the nine images is a frontal and approximately in-the-center shot of the chart, but in no way it has to be precisely controlled.
- How should I frame the nine image shots?
- With the exception of the center-framed shot, frame each shot so that the given boundary of the chart runs as close to the edge of the image frame as possible, but make sure that none of the checkers become clipped outside of the frame. Here is one typical framing sequence:
- First shoot centered straight on.
- Tilt the camera up, thereby effectively framing the chart at the bottom-center of the image.
- Tilt camera down, thereby effectively framing the chart at the top-center of the image.
- Move camera a bit to the left (so that when turning to the right to face the chart, it is about 10 to 30 degrees). Take a series of shots similar to the first three, above, except that the chart is framed at the center-left, top-left, and bottom-left areas of the image.
- Move camera to the right, and do the same for the center-right, top-right, and bottom-right areas of the image.
- Lens aberrations for my lens are more prominent at the image corners and edges. What I can do to improve the lens correction results?
- Try to frame the chart in the view such that checkerboard grids can sample more points along the image corners and edges. It would also help to produce better results if you capture more images with the checkerboard framed around the image corners and edges.
- Can I just keep the camera in one position and move the chart instead?
- It’s recommended that users move the camera instead of the chart so that the lighting remains constant on the chart, which will provide better vignette correction results when processed. When shooting the chart at very close distances, make sure that the camera/tripod setup does not block any lighting during shooting.
- Do I have to have a perfectly even lighting setup?
- No. As long as the lighting setup is consistent between all shots, the Lens Profile Creator can detect the pattern of chart lighting from the multiple shots and calculate the relative light falloff that occurs. An optimum exposure (one that does not clip any of the white highlights of the chart while still capturing the maximum range of possible tonal data) will also aid in generating an optimum vignette correction model. Having said all that, a more evenly illuminated lighting would only help to get a more consistent vignette estimation result.
- What type of paper should I print the chart on?
- A matte, or at least semi-matte, heavyweight paper is recommended. Glossy is not recommended since specular highlights (light reflection off the chart) can interfere with grid detection. A heavyweight paper is recommended so that, when mounted, the printed chart will remain completely flat. The flatness of the chart is essential for accurate lens profiling, though the images themselves may have the chart shot at different angles.
- Can I display the chart image on a flat-screen LCD TV monitor instead of printing it?
- This is a feasible method for shooting chart images for lens profiling, though the quality and potential caveats have not been tested in-house by Adobe. Some user has taken this route and reported good results with the geometric and vignette corrections. Care must be taken to make sure the chart squares display as perfectly square pixels, and that the display is not overexposed. Also, one needs to specify the correct square print dimension in the user interface of Lens Profile Creator.
- Do I have to shoot the chart against a blank background?
- No. The Lens Profile Creator can still detect the chart when it’s set in front of a busy background. Take care to avoid including any spectral highlights in the background that could confuse the Lens Profile Creator’s grid detection (shiny objects or anything particularly bright).
- How many image sets do I need to create a complete profile for my lens?
- It depends on your shooting patterns and expectations. The amount and the type of lens distortions are direct functions of the camera settings, such as the focal length, the focus distance and the aperture. Therefore, to fully characterize the optical properties of a lens, one needs to create a lens profile for each of the many exemplary camera settings. To create one lens profile for one camera settings, one needs to shoot a multiple of calibration chart images (called one image set). Lens Profile Creator is able to batch process all the image sets and append each of the generated lens profile (called the sub-profile) into a single lens profile LCP file.
We recommend the following guidelines when shooting the image sets to create a basic lens profile:- For wide angle/fisheye zoom lenses, shoot at the nominal focal length positions as marked on the ring of the lens with a fixed f/11 aperture.
- For telephoto zoom lenses, shoot at the minimum, maximum and medium focal lengths positions with a fixed f/11 aperture.
- For prime lenses, shoot at (1 × minimum focus distance) and (5 × minimum focus distance) focus distance positions with a fixed f/11 aperture.
- As a step-up for advanced users, we recommend the following guidelines when shooting the image sets to create a more complete lens profile:
- For wide angle/fisheye zoom lenses, shoot (6 focal length positions) × (3 focus distance positions) × (4 aperture positions) = 72 image sets.
- For telephoto zoom lenses, shoot (3 focal length positions) × (3 focus distance positions) × (4 aperture positions) = 36 image sets.
- For prime lenses, shoot (1 focal length position) × (3 focus distance positions) × (4 aperture positions) = 12 image sets.
- For wide angle/fisheye zoom lenses, shoot (6 focal length positions) × (3 focus distance positions) × (4 aperture positions) = 72 image sets.
- How can I create and use LCP files with older lenses that have no EXIF metadata, or with lenses that have simpler, less distinguishable metadata so that they can’t be told apart from each other?
- In the Lens Profile Creator, please specify a fully qualified camera and lens names (including make and model) so that a user can uniquely identifying the lens profile in the user interface.
- What are the different colored grid points that show up when I run the Lens Profile Creator on my images?
- Yellow grid points are the initial corners detected by the Lens Profile Creator. The yellow zigzag dashed line shows the correct ordering of the detected corners. Red grid points indicate grid detection failures that it will remove the image from contributing to the computation of the lens profile. Looking at the red dots and finding where these red dots are missing in the checkerboard can give clues to why the failure occurred. Cyan grid points are drawn as overlays on top of the yellow grid points. The yellow point shows the original detected corner, and the cyan point shows the new location of the corner as predicted by the lens profile. The yellow points and the cyan points should be as close to each other as possible. The closer the points, the better fit of the estimated lens model to the actual data.
- My images show red grid points and there is a yellow warning sign next to the image file name listing item after running them through the Lens Profile Creator. What does this mean? How can I prevent this?
- Red grid points on the image indicate a grid detection failure. The Lens Profile Creator will not include images that are determined to have a grid detection failure. The most common causes are that the user specified the incorrect checkerboard info in the Lens Profile Creator calibration settings, or the presence of specular highlights on the chart, or the chart not being completely in frame, or chart squares being too small in the captured image. In the first case, check to make sure the checkerboard info in the Lens Profile Creator is correctly specified. If the checkerboard info is incorrect, try rerunning the same images after correcting the checkerboard info.
- What is the best methodology for determining the “smallest square” to measure in a group of images?
- Measuring the smallest checker square in a group of images is used by the Lens Profile Creator to help correctly detect the grid. The measurement does not have to be completely accurate; an approximated value is good enough. Scan through your images to find a checker that appears to be the smallest due to the geometric distortion of the lens or the angle it was shot at, and then use the ruler tool to measure across its smallest dimension (length or width) and input the measured data.
- When measuring the square pixel dimension, should the spread of the square due to chromatic aberration or geometric distortion be included in the measurement?
- This measurement is an approximation used by the Lens Profile Creator to help correctly detect the grid, and does not have to be 100% accurate. Including or not including the spread from chromatic aberration should be fine, although measuring the smallest square should take into account squares that are smallest due to geometric distortion. These squares should be considered for measuring the smallest square. It’s also recommended that no square in the image have a dimension shorter than 20 pixels.
- Can the Lens Profile Creator profile APS-C “digital” lenses used on a full-frame body?
- Yes. The full frame sensor is able to sample image data that is beyond the scope of the APS-C lenses, which is not a bad thing.
- Can the Lens Profile Creator profile full-frame lenses used on an APS-C sensor size camera body, and then apply the generated lens profile for lens correction to an image captured with a full-frame camera using the same lens?
- Not recommended, because the camera with the APS-C sized sensor (non full-frame sensor) can only sample a limited range of lens aberration data of the full-frame lenses. Applying the generated lens profile for lens correction to an image captured with a full-frame camera using the same lens amounts to extrapolation of lens aberration data to where it does not have any observation data, which may or may not work well. If your lens is an APS-C type of lens, choose an APS-C type of camera to match it when shooting the calibration chart; else choose a full frame camera body.
- Where should I place my LCP file so that I can use it in ACR and the Photoshop Lens Correction plug in?
- You can place the lens profiles under a user specific or a shared all user location.
User profiles location:- Mac OSX: /Users/(User Name)/Library/Application Support/Adobe/CameraRaw/LensProfiles/1.0
- Windows 7 or Vista: C:\User\(User Name)\AppData\Roaming\Adobe\CameraRaw\LensProfiles\1.0
- Windows XP: C:\Documents and Settings\(User Name)\Application Data\Adobe\CameraRaw\LensProfiles\1.0
- Mac OSX: /Library/Application Support/Adobe/CameraRaw/LensProfiles/1.0
- Windows 7 or Vista: C:\ProgramData\Adobe\CameraRaw\LensProfiles\1.0
- Windows XP: C:\Documents and Settings\All Users\Application Data\Adobe\CameraRaw\LensProfiles\1.0
- The chromatic aberration correction results from my LCP file are not as good as I had hoped. Is there anything I can do to improve this?
- Focus distance also affects the chromatic aberration to a smaller degree. For best result, create a sub profile that matches the focus distance as well. In Photoshop CS5, the sub profiles of the current selected lens profile can be accessed in by right-clicking on the profile. Some camera vendors enable (sometimes randomly) in-camera corrections that cannot be turned off. It is recommended to use the DNG images instead of Tiff or JPEG images to create the profiles.
- What if I only shoot images and profile for the minimum and maximum focal lengths of a zoom lens? Will the Photoshop CS5 still use the profile and make corrections for images shot in between these focal lengths?
- Yes. Photoshop CS5 will interpolate the lens profiles between the two focal lengths.
- How should I meter and expose the calibration chart?
- Spot or center-weighted metering should work fine. The goal is to expose the chart to capture the maximum amount of tonal data possible without clipping the white areas of the chart. It’s recommended that you keep objects brighter than the white of the chart out of the background so that you can view the white of the chart as your highlight area when looking at a histogram of your image.
- When should lens correction be applied in my workflow?
- It is recommended that the lens correction be applied very early in your photographic workflow, before any additional scaling or cropping is applied to the image. The adoption of the non-destructive Camera Raw based workflow is highly recommended.
- Can I still create a lens profile if the camera I use incorporates its own in-camera lens corrections that I can’t turn off?
- If you wish to create lens profile for a camera that uses its own lens corrections, it is recommended that you shoot only raw images to prevent the in-camera lens corrections from being applied. Keep in mind that if you make and use a lens correction profile in this manner, the correction will only work for uncorrected images from the camera.
- I want to profile for different focus distances, but my camera does not record this as EXIF metadata. Can I still profile for different focus distances?
- Yes. Lens Profile Creator estimates the focus distance for each iteration regardless whether or not the focus distance is recorded in the EXIF metadata or not. If the focus distance is recorded in the EXIF metadata, Photoshop CS5 will try to automatically select the best sub profile with the closest focus distance match.
