Camera correcting lens distortions?

Discussion in 'Digital Photography' started by Matthias Heiler, Jul 6, 2004.

  1. Hi group,

    Is there a camera that electronically corrects geometrical lens
    distortions (esp. Barrel)? For the fixed-lens digital cameras out
    there this should be not hard to implement. It also would
    manufacturers allow to use cheaper/lighter glass on their consumer
    products and still get decent image quality.

    On a similar note, does anybody know a decent lens-distortion
    correction software for Linux? It should be able to work on many
    images automatically, without manual intervention.

    Thanks,

    Matthias
    Matthias Heiler, Jul 6, 2004
    #1
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  2. On 06 Jul 2004 11:50:08 +0200, Matthias Heiler <>
    wrote:

    >Is there a camera that electronically corrects geometrical lens
    >distortions (esp. Barrel)? For the fixed-lens digital cameras out
    >there this should be not hard to implement. It also would
    >manufacturers allow to use cheaper/lighter glass on their consumer
    >products and still get decent image quality.


    Matthias,

    I don't have an answer to your question. Only wanted to remark
    that any recalculation that involves pixel relocation will
    necessarily reduce sharpness. I guess that this is one of the
    reasons why nobody may be doing it in the camera.

    There's most likely some software though.

    Hans-Georg

    --
    No mail, please.
    Hans-Georg Michna, Jul 6, 2004
    #2
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  3. Matthias Heiler

    Mxsmanic Guest

    Matthias Heiler writes:

    > Is there a camera that electronically corrects geometrical lens
    > distortions (esp. Barrel)?


    No. It's very difficult because distortions vary with the lens, the
    focal length setting (for zooms), the aperture setting, and even the
    current focus setting. A camera would have to have all this information
    internally recorded for all lenses in order to correct anything.
    Additionally, some types of lens defects cannot be corrected after the
    fact (such as blurriness).

    > It also would
    > manufacturers allow to use cheaper/lighter glass on their consumer
    > products and still get decent image quality.


    They are already using very cheap glass in most cases.

    --
    Transpose hotmail and mxsmanic in my e-mail address to reach me directly.
    Mxsmanic, Jul 6, 2004
    #3
  4. Matthias Heiler

    Ray Paseur Guest

    I am certain that a software product exists for correcting Barrel distortion
    in wide-angle lenses. Sorry I cannot tell you its name! Perhaps Google can
    remember better than I can. It may be a Photoshop plug-in. ~Ray
    "Matthias Heiler" <> wrote in message
    news:-mannheim.de...
    > Hi group,
    >
    > Is there a camera that electronically corrects geometrical lens
    > distortions (esp. Barrel)? For the fixed-lens digital cameras out
    > there this should be not hard to implement. It also would
    > manufacturers allow to use cheaper/lighter glass on their consumer
    > products and still get decent image quality.
    >
    > On a similar note, does anybody know a decent lens-distortion
    > correction software for Linux? It should be able to work on many
    > images automatically, without manual intervention.
    >
    > Thanks,
    >
    > Matthias
    Ray Paseur, Jul 6, 2004
    #4
  5. In article <-mannheim.de>,
    says...
    > Hi group,
    >
    > Is there a camera that electronically corrects geometrical lens
    > distortions (esp. Barrel)? For the fixed-lens digital cameras out
    > there this should be not hard to implement. It also would
    > manufacturers allow to use cheaper/lighter glass on their consumer
    > products and still get decent image quality.
    >
    > On a similar note, does anybody know a decent lens-distortion
    > correction software for Linux? It should be able to work on many
    > images automatically, without manual intervention.
    >
    > Thanks,
    >
    > Matthias
    >

    Panorama Tools will correct barrel and pincushion distortion. It is
    a plugin for photoshop and is free.
    Also lookup ptlens.

    --
    Robert D Feinman
    Landscapes, Cityscapes and Panoramic Photographs
    http://robertdfeinman.com
    mail:
    Robert Feinman, Jul 6, 2004
    #5
  6. "Ray Paseur" <> wrote in message
    news:40ea92bb$0$3085$...
    > I am certain that a software product exists for correcting Barrel

    distortion
    > in wide-angle lenses. Sorry I cannot tell you its name! Perhaps Google

    can
    > remember better than I can. It may be a Photoshop plug-in. ~Ray


    This sort of distortion correction is built into both Paint Shop Pro and
    Pano Tools. Of necessity, there is a sharpness reduction. Whether
    correction would be better done _before_ the Bayer interpolation or after
    is something I would like to know.

    It amuses me that so much effort is put into hardware when to do the same
    in software is relatively simple coding, and it would not need to be
    restricted to fixed-focal length cameras either - a different degree of
    correction for each zoom. However, it is a slow process, and the limited
    CPU power in digital cameras may be hindering implementation.

    Cheers,
    David
    David J Taylor, Jul 6, 2004
    #6
  7. Matthias Heiler <> writes:
    > Is there a camera that electronically corrects geometrical lens
    > distortions (esp. Barrel)?


    AFAIK, no.

    > On a similar note, does anybody know a decent lens-distortion
    > correction software for Linux? It should be able to work on many
    > images automatically, without manual intervention.


    Helmut Dersch' Panorama Tools is what you want. It is free software,
    has been ported to Linux, and is excellent for batch work.

    http://home.no.net/dmaurer/~dersch/Index.htm
    --
    - gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
    ========================================================================
    «To live outside the law, you must be honest.» (Bob Dylan)
    Gisle Hannemyr, Jul 6, 2004
    #7
  8. "David J Taylor" <-this-bit.nor-this-part.uk> writes:

    > It amuses me that so much effort is put into hardware when to do the same
    > in software is relatively simple coding, and it would not need to be
    > restricted to fixed-focal length cameras either - a different degree of
    > correction for each zoom. However, it is a slow process, and the limited
    > CPU power in digital cameras may be hindering implementation.


    I'm thinking along the same line. In the best of all worlds cameras
    with built-in lens (zoom or prime) would be calibrated by the
    manufacturer to correct most distortions automatically. SLRs would
    offer a calibration mode where the user takes some images of a
    reference object (e.g., a poster provided by the manufacturer) and the
    camera measures the distortion of a given lens. Of course, the
    correction could be disabled by the user at any time to allow for
    maximum sharpness (alternatively one can throw in a couple of extra
    megapixels for that).

    I understand the CPU argument: Doing the interpolations correctly
    would probably require much floating point processing power. But it's
    just a matter of time until we have that.

    I wonder if any manufacturers are reading this forum... ;-)
    Matthias Heiler, Jul 6, 2004
    #8
  9. "Matthias Heiler" <> wrote in message
    news:-mannheim.de...
    []
    > I'm thinking along the same line. In the best of all worlds cameras
    > with built-in lens (zoom or prime) would be calibrated by the
    > manufacturer to correct most distortions automatically.


    ... and external lenses could simply provide the required parameters to the
    camera's CPU just like they do for other data today. I don't think
    there's a need to restrict this to built-in lenses, is there?

    > SLRs would
    > offer a calibration mode where the user takes some images of a
    > reference object (e.g., a poster provided by the manufacturer) and the
    > camera measures the distortion of a given lens. Of course, the
    > correction could be disabled by the user at any time to allow for
    > maximum sharpness (alternatively one can throw in a couple of extra
    > megapixels for that).


    Nice one!

    > I understand the CPU argument: Doing the interpolations correctly
    > would probably require much floating point processing power. But it's
    > just a matter of time until we have that.


    ... and perhaps sooner than we expect!

    > I wonder if any manufacturers are reading this forum... ;-)


    ... I should have patented this idea - although I expect someone already
    has.

    Cheers,
    David
    David J Taylor, Jul 6, 2004
    #9
  10. Matthias Heiler

    John Bean Guest

    On Tue, 06 Jul 2004 12:59:24 GMT, David J Taylor wrote:
    > .. and external lenses could simply provide the required parameters to the
    > camera's CPU just like they do for other data today. I don't think
    > there's a need to restrict this to built-in lenses, is there?


    > .. I should have patented this idea - although I expect someone already
    > has.


    Olympus. 4/3 system has provision to do this, don't know if the E-1
    currently does though.

    --
    John Bean

    Electricity is actually made up of extremely tiny particles called
    electrons, that you cannot see with the naked eye unless you have been
    drinking (Dave Barry)
    John Bean, Jul 6, 2004
    #10
  11. On Tue, 06 Jul 2004 13:14:09 +0200, Mxsmanic
    <> wrote:

    >No. It's very difficult because distortions vary with the lens, the
    >focal length setting (for zooms), the aperture setting, and even the
    >current focus setting. A camera would have to have all this information
    >internally recorded for all lenses in order to correct anything.
    >Additionally, some types of lens defects cannot be corrected after the
    >fact (such as blurriness).


    Actually I find the thought fascinating. Who knows, perhaps in a
    couple of years we will have cheap cameras with a fixed, cheap
    lens and a nonhomogeneous sensor field (higher pixel density in
    the center). The camera will take a rather raw image, and all
    the fine work, zooming, all kinds of corrections, will be done
    by the built-in computer.

    One way to increase picture quality could be to take several
    photos in quick succession, then process the whole series,
    concentrate on the one that is least blurred, take details of
    moving objects from other shots in the sequence, etc.

    Hans-Georg

    --
    No mail, please.
    Hans-Georg Michna, Jul 6, 2004
    #11
  12. "Hans-Georg Michna" <> wrote in message
    news:...
    []
    > One way to increase picture quality could be to take several
    > photos in quick succession, then process the whole series,
    > concentrate on the one that is least blurred, take details of
    > moving objects from other shots in the sequence, etc.
    >
    > Hans-Georg


    Already partially available as "best shot selector" in the Nikon Coolpix
    series. Selects the single "best" (i.e. sharpest) of a series of
    images..... Doesn't do the image combination, though!

    Cheers,
    David
    David J Taylor, Jul 6, 2004
    #12
  13. Hans-Georg Michna <> writes:

    >I don't have an answer to your question. Only wanted to remark
    >that any recalculation that involves pixel relocation will
    >necessarily reduce sharpness.


    Not necessarily, at least not visibly. A high-quality resampling
    algorithm (e.g. Lanczos-windowed sinc) will allow you to make small
    local scale changes (which is all that's needed to correct moderate
    barrel or pincushion distortion) with no visible loss of information.

    >I guess that this is one of the
    >reasons why nobody may be doing it in the camera.


    Good resampling is expensive in CPU resources (lots of multiplies and
    adds), which is more likely why nobody is doing it in the camera.

    Dave
    Dave Martindale, Jul 6, 2004
    #13
  14. Matthias Heiler

    jaf Guest

    Ya! This one. http://www2.keck.hawaii.edu/geninfo/about.html

    --
    John
    johnf 202 at hotmail dot com


    "Matthias Heiler" <> wrote in message
    news:-mannheim.de...
    | Hi group,
    |
    | Is there a camera that electronically corrects geometrical lens
    | distortions (esp. Barrel)? For the fixed-lens digital cameras out
    | there this should be not hard to implement. It also would
    | manufacturers allow to use cheaper/lighter glass on their consumer
    | products and still get decent image quality.
    |
    | On a similar note, does anybody know a decent lens-distortion
    | correction software for Linux? It should be able to work on many
    | images automatically, without manual intervention.
    |
    | Thanks,
    |
    | Matthias
    jaf, Jul 6, 2004
    #14
  15. Mxsmanic <> writes:

    >No. It's very difficult because distortions vary with the lens, the
    >focal length setting (for zooms), the aperture setting, and even the
    >current focus setting. A camera would have to have all this information
    >internally recorded for all lenses in order to correct anything.


    With a typical non-SLR, there's only one lens. You still have to model
    its distortion as a function of the things you name, but a table could
    be calculated automatically by the lens design software and included in
    the firmware of the camera. Better yet, each camera could have an
    individual table based on the measured performance of that specific lens
    as it came from manufacturing, not the lens as it was designed.

    >Additionally, some types of lens defects cannot be corrected after the
    >fact (such as blurriness).


    In fact, geometric distortion is probably the *only* lens aberration
    that could be fully corrected in software. Geometric distortion causes
    a point on the object to be imaged as a point on the sensor, just in
    slightly the wrong location. Almost all other lens aberrations cause a
    point to be imaged as a blob instead of a point, and that can't be
    corrected without causing other problems.

    Dave
    Dave Martindale, Jul 6, 2004
    #15
  16. Matthias Heiler

    Mxsmanic Guest

    Dave Martindale writes:

    > With a typical non-SLR, there's only one lens. You still have to model
    > its distortion as a function of the things you name, but a table could
    > be calculated automatically by the lens design software and included in
    > the firmware of the camera. Better yet, each camera could have an
    > individual table based on the measured performance of that specific lens
    > as it came from manufacturing, not the lens as it was designed.


    It would be cheaper to just build a better lens.

    --
    Transpose hotmail and mxsmanic in my e-mail address to reach me directly.
    Mxsmanic, Jul 6, 2004
    #16
  17. Bart van der Wolf, Jul 6, 2004
    #17
  18. "Mxsmanic" <> wrote in message
    news:...
    SNIP
    > It would be cheaper to just build a better lens.


    Maybe, maybe not. A lens is ALWAYS a compromise between different
    corrections. Improve one, another one gets worse. There are too many degrees
    of freedom in lens design.

    http://www.dpreview.com/news/0402/04020301dxoopticspro.asp may somewhat
    reduce most residual artifacts after the fact, although at the expense of
    resampling which will reduce resolution a bit.

    Bart
    Bart van der Wolf, Jul 6, 2004
    #18
  19. Matthias Heiler <> schrieb:
    >
    > On a similar note, does anybody know a decent lens-distortion
    > correction software for Linux? It should be able to work on many
    > images automatically, without manual intervention.


    Try hugin (hugin.sf.net) to find the parameters for your lens, and then
    use them in a script with Panorama Tools.

    Walter
    Walter Hofmann, Jul 6, 2004
    #19
  20. Matthias Heiler

    Guest

    In message <>,
    Hans-Georg Michna <> wrote:

    >I don't have an answer to your question. Only wanted to remark
    >that any recalculation that involves pixel relocation will
    >necessarily reduce sharpness. I guess that this is one of the
    >reasons why nobody may be doing it in the camera.


    >There's most likely some software though.


    The best way, I would think, is to treat the three color planes of the
    RAW image data as elastic bitmaps, so that software can work without the
    restrictions of a raster grid, more or less like a plane object with
    millions of vertices in a single plane, in a 3D program. The three
    layers could be moved together for lens and perspective corrections, and
    they could be moved independently of each other to counteract chromatic
    abberation. Then, the data could be be rendered to a gridded raster
    file of a size much larger than the original capture, without
    significant loss or distortion of detail, for printing purposes, or
    rendered at a smaller size for full image viewing onscreen, if printing
    is not needed. The whole idea of moving detail from one pixel to
    another is from the stone age.
    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <>
    ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
    , Jul 7, 2004
    #20
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