Dynamic range

Discussion in 'Digital Photography' started by Marvin Margoshes, Sep 9, 2003.

  1. The question about the dynamic range of film vs. digital comes up regularly. There is an interesting article about this, for the serious reader, by Kodak researchers. The reference is "Extending the Color Gamut and Dynamic Range of a sRGB Image Uisng a Residual Image", K. E. Spauldin, G. J. Woolfe, and R. L. Joshi, Color Research and Application, Vol. 28, Noi. 4, 251-266 (2003). There is a less technical summary at http://www.kodak.com/US/en/corp/researchDevelopment/technologyFeatures/eri.shtml.

    Briefly, the authors point out that both digital images as taken, and film images in the form of negative, have more dynamic range and color gamut than can be represented in a print or a monitor. The extra dynamic range can be utilized in conventional printing by dodging, and in digital printing by analogous methods.

    Storing digital images in conventional formats loses some of the information. The authors describe a way to capture the information not in a .jpg file, for example, and save it as attached exif, so that the information can later be used. The method is used in some of Kodak's pro-level digicams.
     
    Marvin Margoshes, Sep 9, 2003
    #1
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  2. Marvin Margoshes

    Lionel Guest

    Word has it that on Tue, 9 Sep 2003 09:50:46 -0400, in this august
    Excellent! Thanks for the link, it'll come in handy when I'm explaining
    to people why I shoot in RAW format instead of JPEG format.
    Exactly as I said in recent thread on the topic in this (RPD) newsgroup.
     
    Lionel, Sep 9, 2003
    #2
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  3. Marvin Margoshes

    Don Stauffer Guest

    This subject is complicated by the problem that there are really two
    kinds of dynamic range in digital photography.

    The first we could call small signal dynamic range, and is basically
    signal to noise ratio. Film photography has a very high value for this
    kind of dynamic range (at least for most films). The other is the large
    signal analysis, basically the ratio of the largest possible signal to
    the lowest possible signal. Both film and digital has this kind of
    dynamic range. However, if the noise is too high in a digital system,
    this large signal dynamic range is meaningless. Yet that is generally
    the type of dynamic range we discuss in film systems.
     
    Don Stauffer, Sep 10, 2003
    #3
  4. The conventional definition of dynamic range, in all electronics fields I
    know of, is the difference between the smallest signal distinguisable form
    noise and the maximum signal below saturation. The signal-to-noise ratio
    (S/N) is a different parameter. It is best not to confuse apples and
    oranges.
     
    Marvin Margoshes, Sep 12, 2003
    #4
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