Removing Moiré Effects

Digital cameras sometimes produce fine interference patterns known as moiré effects, like the one shown in the image detail in Figure 7-58. These patterns can be removed from digital images using the following method:

  1. Create a new, combined interim layer, (as described in Figure 7-49) or a copy of the background layer if no other layers are present.

    Image (a cut out) with a strong moiré effect

    Figure 7-58. Image (a cut out) with a strong moiré effect

  2. Use the Filter ▸ Noise ▸ Dust & Scratches command with a radius setting appropriate to the image resolution (here, between 3 and 6 pixels). The preview image (Figure 7-59) appears very blurred, but this is not a problem.

  3. Set the blending mode to Color (Figure 7-60).

The image now looks a lot better, as you can see in Figure 7-61.

The Dust & Scratches filter removes the moiré effect but leaves the image looking quite blurred.

Figure 7-59. The Dust & Scratches filter removes the moiré effect but leaves the image looking quite blurred.

We often use an even stronger filter effect that we then moderate by varying the layer opacity.

The layer stack after moiré correction

Figure 7-60. The layer stack after moiré correction

The corrected image with reduced moiré

Figure 7-61. The corrected image with reduced moiré

Some RAW editors (e.g., Capture One) also provide a function for reducing moirés. If available, we prefer the RAW editor correction.

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