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What went wrong?

My scans look much grainier or noisier than the negative

Scans

What you're seeing

The scan shows harsh, clumpy grain or coloured speckled noise, often worst in the darkest parts of slides or the brightest parts of negative scans.

Check this first

Check this first

Is the noise in the dense parts of the film (shadows on slides, highlights on negatives) or everywhere?

Likely causes, most common first

  1. 01

    Real film grain, made harsher by sharpening

    Common
    How to tell
    Grain is even across the frame and matches what you see with a strong loupe, just more prominent. Scans with sharpening on look worse.
    Test it
    Scan once with all sharpening off and once with it on. Compare at the same size as your final use, not at 100 %.
    The fix
    Turn off scanner sharpening and sharpen lightly later. Judge grain at the final viewing size.

    Source Norman Koren (normankoren.com), Understanding image sharpness part 8: Grain and sharpness in scans and enlarger prints

  2. 02

    Scanner noise in dense areas

    Common
    How to tell
    Coloured speckles or mottling only in the densest parts of the film: the dark shadows on slides, the bright highlights on negatives. Thinner areas are clean.
    Test it
    Rescan with multi-sampling, more passes, or a second longer exposure (multi-exposure) if your scanner and software offer them. If the speckles reduce, it was scanner noise.
    The fix
    Use multi-sampling or multi-exposure where supported. Keep the film still between passes.

    Sources Hamrick Software (VueScan), VueScan Manual: Input Tab; LaserSoft Imaging (SilverFast), Multi-Exposure increases Dynamic Range for scanning

  3. 03

    Infrared cleaning on black-and-white silver film

    Occasional
    How to tell
    Black-and-white scans have blobby, smeared clumps of grain, or odd patches, only when dust removal is on.
    Test it
    Scan the frame with infrared cleaning off. If the clumps vanish, turn it off for this film.
    The fix
    Leave infrared cleaning off for silver black-and-white film and use software dust removal instead.

    Sources LaserSoft Imaging (SilverFast), iSRD is SilverFast's dust and scratch removal using infrared technology; Epson America, Perfection V800 Photo/V850 Pro User's Guide: Removing Dust and Scratch Marks Using DIGITAL ICE Technology; Hamrick Software (VueScan), VueScan Manual: Scanning slides and negatives

  4. 04

    Grain aliasing

    Rare
    How to tell
    Grain looks larger and rougher than in a good darkroom print or under a loupe, and changes in character when you change scan resolution.
    Test it
    Scan the same area at two different resolutions and compare at the same output size. If the grain pattern changes character, aliasing is involved.
    The fix
    Scan at a higher resolution and downsize with a good resampling method, rather than scanning at a low resolution.

    Sources Norman Koren (normankoren.com), Understanding image sharpness part 8: Grain and sharpness in scans and enlarger prints; Hamrick Software (VueScan), VueScan Manual: Maximizing Image Quality

Avoiding it next time

  • Turn off scanner sharpening.
  • Use multi-sampling for dense slides.
  • Scan high and downsize rather than scanning low.

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