Erwin Puts on AA filters (in his M8 review)

Discussion in 'Digital Photography' started by Philip Homburg, Nov 14, 2006.

  1. From <http://www.imx.nl/photosite/leica/M8_2/t007.html>:
    "The Leica M solution is less dependent on the post-processing
    "software and will allow the optical quality of the lenses to be
    "recorded as honest as possible.

    Fortunately, the rest of his review shows that Leica cannot escape the
    laws of physics.

    Somewhat related to this: does anyone know of a set of torture tests
    for Bayer-pattern reconstruction algorithms?


    --
    That was it. Done. The faulty Monk was turned out into the desert where it
    could believe what it liked, including the idea that it had been hard done
    by. It was allowed to keep its horse, since horses were so cheap to make.
    -- Douglas Adams in Dirk Gently's Holistic Detective Agency
     
    Philip Homburg, Nov 14, 2006
    #1
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  2. "Philip Homburg" <> wrote in message
    news:sokit2t3kjuvgb202u3j4mktc7@inews_id.stereo.hq.phicoh.net...
    SNIP
    > Somewhat related to this: does anyone know of a set of torture tests
    > for Bayer-pattern reconstruction algorithms?


    That depends on which aspect of Bayer CFA reconstruction you want to
    torture ... ;-)

    For a simulation of real life objects, you can use a Siemens star
    similar to what Erwin Putz used. Unfortunately his version had a wrong
    gamma, and the centre of the pattern was not avaiable for torture.
    That center will show the worst behavior, lines become hyperboles that
    debunk the myth that aliasing always looks like detail (like in the
    DPreview tests of the Foveon sensors).

    I have since quite a while back made 2 of these targets available to
    produce one's own printed version:
    For HP/Canon inkjet printers (3.8MB):
    http://www.xs4all.nl/~bvdwolf/main/downloads/Jtf60cy-100mm_600ppi.gif
    For Epson inkjet printers (5.3MB):
    http://www.xs4all.nl/~bvdwolf/main/downloads/Jtf60cy-100mm_720ppi.gif

    I could make available a version with a higher number of cycles, but
    it would also require a better than average print quality (it could
    become more of a printer than a camera test). The benefit of a star
    target is that it also allows to determine the limiting resolution of
    lens+sensor, and quantification is easy.

    Another target specifically suited for detection of aliasing artifacts
    is a zoneplate type of target, like the one I used for my
    down-sampling aliasing artifact test:
    <http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/down_sample.htm>
    , but a larger version is needed for print. In a way, imaging such a
    target on a sensor is also a size reduction.

    --
    Bart
     
    Bart van der Wolf, Nov 14, 2006
    #2
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  3. In article <455a3e01$0$330$4all.nl>,
    Bart van der Wolf <> wrote:
    >For a simulation of real life objects, you can use a Siemens star
    >similar to what Erwin Putz used.


    Some time ago I already wrote a program that generates them in
    various ways.

    >Another target specifically suited for detection of aliasing artifacts
    >is a zoneplate type of target, like the one I used for my
    >down-sampling aliasing artifact test:
    ><http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/down_sample.htm>
    >, but a larger version is needed for print. In a way, imaging such a
    >target on a sensor is also a size reduction.


    Yes, that is also a nice one.

    But, just thinking about the problem, I came up with a number of other
    special cases. Saturated colors for example. Or very fine lines on a
    black background.


    --
    That was it. Done. The faulty Monk was turned out into the desert where it
    could believe what it liked, including the idea that it had been hard done
    by. It was allowed to keep its horse, since horses were so cheap to make.
    -- Douglas Adams in Dirk Gently's Holistic Detective Agency
     
    Philip Homburg, Nov 14, 2006
    #3
  4. "Philip Homburg" <> wrote:
    > From <http://www.imx.nl/photosite/leica/M8_2/t007.html>:
    > "The Leica M solution is less dependent on the post-processing
    > "software and will allow the optical quality of the lenses to be
    > "recorded as honest as possible.
    >
    > Fortunately, the rest of his review shows that Leica cannot escape the
    > laws of physics.
    >
    > Somewhat related to this: does anyone know of a set of torture tests
    > for Bayer-pattern reconstruction algorithms?


    One of the Japanese digital camera magazines used to do a color pattern test
    (the Nikon D100 did best in its generation) but they stopped doing that
    years ago.

    Bart has a downloadable star pattern chart similar to the one in the review
    that reliably produces Bayer demosaicing infelicities with a sharp lens with
    both the 300D and 5D.

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Nov 15, 2006
    #4
  5. Philip Homburg

    Scott W Guest

    Philip Homburg wrote:
    > From <http://www.imx.nl/photosite/leica/M8_2/t007.html>:
    > "The Leica M solution is less dependent on the post-processing
    > "software and will allow the optical quality of the lenses to be
    > "recorded as honest as possible.
    >
    > Fortunately, the rest of his review shows that Leica cannot escape the
    > laws of physics.
    >
    > Somewhat related to this: does anyone know of a set of torture tests
    > for Bayer-pattern reconstruction algorithms?
    >


    How about lawn furniture?
    http://www.pbase.com/northqueenslandphotos/image/62850197/original

    Scott
     
    Scott W, Nov 15, 2006
    #5
  6. In article <>,
    Scott W <> wrote:
    >Philip Homburg wrote:
    >> Somewhat related to this: does anyone know of a set of torture tests
    >> for Bayer-pattern reconstruction algorithms?

    >
    >How about lawn furniture?
    >http://www.pbase.com/northqueenslandphotos/image/62850197/original


    Two things are missing in this one:
    - repeatability
    - completeness

    I'd like to have synthetic images that touch as many problem areas as
    possible.


    --
    That was it. Done. The faulty Monk was turned out into the desert where it
    could believe what it liked, including the idea that it had been hard done
    by. It was allowed to keep its horse, since horses were so cheap to make.
    -- Douglas Adams in Dirk Gently's Holistic Detective Agency
     
    Philip Homburg, Nov 15, 2006
    #6
  7. In article <455a3e01$0$330$4all.nl>,
    Bart van der Wolf <> wrote:
    >Another target specifically suited for detection of aliasing artifacts
    >is a zoneplate type of target, like the one I used for my
    >down-sampling aliasing artifact test:
    ><http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/down_sample.htm>
    >, but a larger version is needed for print. In a way, imaging such a
    >target on a sensor is also a size reduction.


    Putting DC on the outside also results in in interesting image.

    <http://misc.hq.phicoh.net/tmp/circles.png>


    --
    That was it. Done. The faulty Monk was turned out into the desert where it
    could believe what it liked, including the idea that it had been hard done
    by. It was allowed to keep its horse, since horses were so cheap to make.
    -- Douglas Adams in Dirk Gently's Holistic Detective Agency
     
    Philip Homburg, Nov 17, 2006
    #7
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