digital cleanup of old slide

Discussion in 'Photoshop Tutorials' started by George, May 5, 2005.

  1. George

    Hunt Guest

    No, I do not think I am missing the point. Tom's comment on X-posting was that
    it was a good thing. I agreed with that 100%. In this case it should be

    Hunt, May 10, 2005
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  2. Read my post again please. Did I say otherwise?
    Johan W. Elzenga, May 11, 2005
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  3. George

    Hunt Guest

    I suppose you're correct - I am missing the point. By my reading, we are both
    saying the same thing. I agree that this article SHOULD have been X-posted to
    the relevant NGs. Beyond that, I am at a complete loss, as to what other "
    point" I am missing.

    Hunt, May 12, 2005
  4. George

    Ctein Guest

    Dear Johan & George,

    Physical cleaning of mildewed films is a very dicey proposition. As the
    mildew digests the emulsion, it breaks down the crosslinking between the
    proteins and renders the emulsion both fragile and soluble. A
    hydrocarbon-based cleaner may remove a little of the mildew but it may also
    cause pieces of the emulsion to break off, even with a most delicate touch.
    Water-based detergent-type cleaners can remove a lot more of the mildew, but
    if the emulsion is too damaged, it will wash right off! Some otherwise
    excellent cleaners, like PEC-12, have warnings against using them with
    unhardened gelatin because they can dissolve it; consequently, they can
    dissolve mildew-damaged emulsions.

    Here's a trick for dealing with seriously-mildewed skies that will work even
    with Photoshop 7 on 16-bit images. Apply a Gaussian blur and set that
    history state for your history brush. Step back to the previous history
    state (undoing the blur) and set the brush option for lighten at 100%
    strength. Paint over the entire area with the history brush; it will
    lighten the filaments yet leave the areas between them almost untouched.
    Apply the Gaussian blur filter again, assign the new blur state to the
    history brush and repeat the process. You can keep repeating this process
    until the filaments go away entirely, but you may not want to. If the blue
    sky isn't entirely featureless and has some fine film grain, applying the
    lightening blur is also having the effect of favoring the lighter spaces
    between grains and lightening up the sky a bit. The important thing is to
    know when to stop. When the average color of the sky looks good, do a
    normal non-lightening blur one final time and just leave it.

    pax / Ctein

    -- Ctein's Online Gallery
    -- Digital Restorations
    Ctein, May 19, 2005
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