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Thread: Imacon Sharpening

  1. #1
    Kirk Gittings's Avatar
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    Imacon Sharpening

    Imacons method of sharpening is to covert the file to LAB, select the Lightness channel and sharpen that channel only and convert back to RGB color (or back to Grayscale). Does anyone understand the advantage to this. For Color or B&W?
    Thanks,
    Kirk

    "When did photography become a desk job?" Kirk Gittings 2009

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  2. #2
    Founder QT Luong's Avatar
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    Imacon Sharpening

    That's a fairly standard technique (some advocate always doing that for sharpening). It is supposed to reduce color noise as minor shifts in color in the sharpened areas. The two conversions introduce rounding errors, though, and if you do it in PS, it is best done by doing a Fade in Luminosity mode.

  3. #3

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    Imacon Sharpening

    What QT said.

    By sharpening in the L mode, you avoid sharpening the A & B channel color data....which lessens the appearance of of chroma noise....typically red and blue spots like film grain.

  4. #4
    Kirk Gittings's Avatar
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    Imacon Sharpening

    So there is no advantage to doing this with a grayscale image. I have tried it with a grayscale image and a b&w RGB file comparing the sharpened original file vs, sharpening just the L channel and can see no difference at all.
    Thanks,
    Kirk

    "When did photography become a desk job?" Kirk Gittings 2009

    KIRK GITTINGS
    WEBSITE

    LIGHT+SPACE+STRUCTURE (blog)

  5. #5

    Imacon Sharpening

    Kirk, that's right. For a greyscale image, or for a color image with no significant data in the A and B channels in Lab mode, there's no advantage at all.

  6. #6
    Kirk Gittings's Avatar
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    Imacon Sharpening

    I am trying to understand this as a friend of mine just bought a 949 and we are going to start testing it next week.
    Thanks,
    Kirk

    "When did photography become a desk job?" Kirk Gittings 2009

    KIRK GITTINGS
    WEBSITE

    LIGHT+SPACE+STRUCTURE (blog)

  7. #7

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    Imacon Sharpening

    Kirk,

    ANYONE who just bought a 949 would be my friend too.

  8. #8

    Imacon Sharpening

    Sharpening with this method can make a difference for grayscale if you're converting from color to black and white by channel mixing or in calculations. The idea was originally dreamed up to smooth over the horrible grain and noise patterns of the first digital press cameras sold to newspapers.

    Going to Lab also offered the technical opportunity to click on the A and B channels individually to check for random digital noise, then smooth those patterns with the 'dust and scratches' filters.

    Almost all of the modern scanners and digital cameras have built-in noise reduction and sharpening, or at least they try. However, those who had to learn the hard way when the first digital equipment came on the market still have a habit of checking those channels to see where the noise is.

    We also did most of our light/dark toning in the Lab channel-lightness selection because we could actually lighten the image for production without a color shift.
    "I meant what I said, not what you heard"--Jflavell

  9. #9
    Kirk Gittings's Avatar
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    Imacon Sharpening

    Dave,

    Amen! He owns an international web based film recorder business, Gamma Tech. He needed to reinvest some profits before tax season. After I work with him awhile he will be offering high res 4x5 scans for $30.00 mailorder.

    John, interesting!-next time I have some noise issues I will check that out.
    Thanks,
    Kirk

    "When did photography become a desk job?" Kirk Gittings 2009

    KIRK GITTINGS
    WEBSITE

    LIGHT+SPACE+STRUCTURE (blog)

  10. #10

    Imacon Sharpening

    Kirk. Was that a typo? $30.00? 4x5 High Res? He wants to start his own religion and needs followers, right?
    "I meant what I said, not what you heard"--Jflavell

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