What Causes Moiré Patterns and How to Fix Them

Moiré patterns are distracting, wavy interference artifacts that appear in digital images when a repetitive physical pattern clashes with the grid of a camera sensor. This article explains the technical causes behind moiré, particularly optical aliasing, and outlines practical post-processing techniques in software like Adobe Photoshop and Lightroom to eliminate both the false color and texture artifacts caused by this phenomenon.

What Causes Moiré Patterns

Moiré occurs due to a phenomenon known as aliasing. In digital photography, camera sensors use an array of discrete pixels to sample light. When a subject features a fine, repetitive pattern—such as tightly woven fabric, brickwork, window screens, or digital monitors—that pattern has a high spatial frequency.

If this spatial frequency exceeds the Nyquist limit of the camera’s sensor (half of the sensor’s sampling rate), the sensor cannot accurately resolve the detail. Instead of recording the true pattern, the sensor misinterprets the overlapping frequencies, producing a new, artificial pattern with a lower spatial frequency. This manifests visually as wavy lines, zebra stripes, or bands of false rainbow colors (chrominance moiré).

The risk of moiré is higher in modern digital cameras that omit an Optical Low-Pass Filter (OLPF) or anti-aliasing filter to maximize sensor sharpness.

How to Remove Moiré During Image Editing

Moiré typically presents two problems: color contamination (chroma moiré) and structural distortion (luminance moiré). Different editing methods target one or both of these issues.

1. Using the Moiré Slider in Lightroom and Adobe Camera Raw

The quickest method to resolve moiré is through Adobe Camera Raw or Lightroom’s localized adjustment tools (Brush, Linear Gradient, or Radial Gradient).

  1. Select the Adjustment Brush (or press K).
  2. Paint directly over the affected area to create a mask.
  3. Locate the Moiré slider under the adjustment panel and drag it toward the right (+50 to +100).
  4. The tool works primarily by neutralizing the chromatic aberration and color shifts while slightly blending adjacent micro-contrast to dissolve the pattern.

2. Eliminating Color Moiré in Photoshop Using Blend Modes

When moiré appears as colorful rainbow bands on neutral fabric or surfaces, the color can be removed without sacrificing the underlying texture.

  1. Open the image in Photoshop and add a new blank layer above the background.
  2. Change the blending mode of this new layer to Color.
  3. Select the Eyedropper Tool (I) and sample the true, neutral color of the fabric immediately adjacent to the moiré.
  4. Select a soft Brush Tool (B) with low flow (around 20–30%) and paint over the false colors on the new layer. This replaces the artifact colors with the correct tone while leaving the texture intact.

Alternatively, use a Hue/Saturation Adjustment Layer:

  1. Target the specific hue channel that the moiré introduced (e.g., Magentas or Cyans).
  2. Lower the Saturation slider until the false color disappears.
  3. Invert the layer mask (Ctrl+I or Cmd+I) and paint with white only over the affected area.

3. Fixing Luminance Moiré via Frequency Separation

If the physical wavy texture remains after removing false colors, use frequency separation to soften the pattern on the high-frequency layer.

  1. Create a frequency separation setup dividing the image into high frequency (texture) and low frequency (color and tone).
  2. Select the High Frequency layer.
  3. Use the Clone Stamp Tool (S) set to sample Current Layer.
  4. Set the stamp opacity to 50% and sample a nearby area of the fabric that has an even, unaffected weave, then gently clone over the moiré texture.
  5. Alternatively, use the Healing Brush Tool on the texture layer to blend the irregular interference lines into the uniform grain of the material.