What lens distortion model does Adobe Lightroom use for lens correction?

Asked 1/12/2016

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I use Adobe Lightroom to correct barrel distortion in GoPro images and want to understand the math behind it. Does Lightroom use the Brown-Conrady lens distortion model, or a different model? If Adobe has separate models for rectilinear and fisheye lenses, what are they?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

10y ago

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Does anyone know if this software uses the Brown-Conrady model to achieve the lens correction?

Yes they do use those very common camera calibration coefficients. I added some copyable text versions of the formulas to the following quote:

Adobe Camera Model

Geometric Distortion Model for Rectilinear Lenses

rectilinear distortion model

xd = (1 + k1*r^2 + k2*r^4 + k3*r^6)*x + 2*(k4*y + k5*x)*x + k5*r^2
yd = (1 + k1*r^2 + k2*r^4 + k3*r^6)*y + 2*(k4*y + k5*x)*y + k5*r^2

Geometric Distortion Model for Fisheye Lenses

fisheye distortion model

rd = f*(θ + k1*θ^3 + k2*θ^5)

While the formulas look a bit different from those that can be found on the Wikipedia page on distortion at first glance:

x wikipedia y wikipedia

they are actually equivalent if you do the math: k4 = P1 and k5 = P2.

The model also includes lateral chromatic aberration and vignetting, which can be found in the linked pdf file.


I'd like to add the breadcrumbs that lead me to the findings above, because

extensive Google search

didn't cut it for me either and getting to the goal was not as straight forward as I would have hoped. This is mostly anecdotal

  1. The Adobe Lens Profile Creator User Guide Version 1.0 Wednesday, April 14, 2010 does what its name implies and guides users through the profile creator software. Procedure Preferences and Other Options in the Adobe Lens Profile Creator, step 4:

    This is a feature made available to lens manufacturers for converting their lens design data into LCP files. For details, check out the companion document titled “Adobe Camera Model Lens Design Data Conversion Guide” on the lens design data interchange format and conversion steps. If there is a document on how to convert to/from LCP files, they should have an open specification of that file format somewhere. Knowing what the profile looks like is half the deal.

  2. I could not find the Adobe Camera Model Lens Design Data Conversion Guide.
  3. In a mailing list archive of darktable-users from 2015-05-13, the support for LCP files is by the lens correction library lensfun is announced:

    The Lensfun repository now contains a branch "acm" which implements the Adobe Camera Model for distortion (including fisheye) It looks like the conversion mentioned above is happening in real life.

  4. The mailing list links to a part of the lensfun documentation 0.3.2.0 named Converting Adobe LCP files to Lensfun: lensfun‑convert‑lcp (Generated on Tue Dec 22 2015):

    The LCP file format is defined by Adobe (see the specification1) and used in their Lightroom and Photoshop products.

    but the specification is blocked by a Spectral Wolf

  5. The Spectral Wolf fears only fire. I can no longer help you, but if you master the wolf, he will undistort your images. Godspeed.

1 that points to macromedia.com. It looks like Adobe keeps old links alive.

Originally by user35348. Source · Licensed CC BY-SA 4.0

user35348

10y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

Lightroom appears to use Adobe’s camera/lens correction model, which for rectilinear lenses is effectively equivalent to the common Brown-Conrady model.

From the community answers, Adobe’s rectilinear distortion formula uses radial terms (k1, k2, k3) plus tangential/decentering terms (k4, k5). Although written differently, it matches the usual Brown-Conrady approach after rearranging the terms, with k4 and k5 corresponding to the tangential parameters often called P1 and P2.

For fisheye lenses, Adobe uses a different model based on angle theta, of the form: rd = f * (theta + k1theta^3 + k2theta^5)

Also, Lightroom and similar raw processors may not rely only on a generic mathematical model in every case. For popular lenses and cameras, they often apply calibrated lens profiles based on measured real-world behavior, which can be more accurate than assuming ideal rotational symmetry alone. That is especially relevant for action cameras like GoPro, where built-in profiles are commonly available.

UniqueBot

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10y ago

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