Moiré—pronounced "moh‑ray"—is a visual distortion that surfaces when a camera’s sensor can’t resolve the fine, repetitive details of a subject. The result is a wavy, sometimes rainbow‑like pattern that can ruin an otherwise sharp image.
Many photographers encounter moiré on tightly woven fabrics, striped fabrics, or any surface with a grid or fine texture. Even high‑end DSLRs and mirrorless bodies can display this effect if the pattern frequency outpaces the sensor’s resolution.
Below you’ll find a practical guide to why moiré occurs, when it’s most likely to appear, and step‑by‑step solutions—both in-camera and in post‑processing.
How Moiré Forms
The phenomenon arises when two periodic patterns overlay: the sensor’s pixel grid and the subject’s repeating pattern. The sensor samples light at discrete intervals; if the subject’s lines are too close together, the sensor interprets them as a new, larger pattern. This mismatch causes the confusing, wavy artifacts that we recognize as moiré.
Why Modern Cameras Still Show Moiré
While many cameras now include optical low‑pass (anti‑aliasing) filters that blur high‑frequency detail just enough to prevent aliasing, this blur also reduces overall sharpness. Photographers often opt to turn the filter off or use sensors with finer resolution, which can reintroduce moiré in certain scenarios. The key takeaway is that the effect is more about the subject’s texture than the camera model.
Common Sources of Moiré
Typical culprits include:
- Woven or knitted fabrics
- Fine printed patterns
- Architectural grid lines (e.g., windows, railings)
- Textured backgrounds like brick or tiles
Optical Low‑Pass Filter Explained
An optical low‑pass filter (OLPF) sits in front of the sensor and slightly diffuses incoming light. By suppressing high‑frequency detail, it prevents aliasing but also reduces sharpness. Some modern mirrorless cameras allow users to disable the OLPF to capture maximum detail, at the risk of moiré.
In‑Camera Techniques to Minimize Moiré
Zoom In and Inspect
After taking a shot, zoom in on the camera’s LCD. Even subtle patterns become obvious at 10‑x magnification. If you spot moiré, consider retaking the photo with a different setup.
Adjust Your Distance
Moving closer to the subject stretches the repeating pattern, giving the sensor a clearer separation between lines. This can eliminate or soften moiré. When working with fragile subjects, use a zoom lens or a close‑up adapter instead of physically approaching.
Experiment With Aperture
A wider aperture (lower f‑number) increases depth of field but can accentuate fine detail. A smaller aperture (higher f‑number) helps blur the offending pattern just enough to hide it. In practice, stopping down to f/11 or f/16 often reduces moiré without a noticeable loss in image quality.
Shift Focus or Change Angle
Re‑focusing to a slightly different plane or angling the camera can alter the relative orientation of the pattern to the sensor grid, breaking the interference that creates moiré. This technique is especially useful for architectural subjects.
Post‑Processing Solutions
Using Lightroom’s Adjustment Brush
Open the Adjustment Brush tool, set the Moiré slider to 100, and paint over the affected area. Adjust brush size as needed. While this won’t remove the artifact entirely, it can soften its appearance and restore a more natural look.
Photoshop’s Camera Raw Filter
Open the image in Photoshop, then launch Camera Raw. Use the Moiré slider (similar to Lightroom) to reduce the effect. Photoshop’s additional tools—such as the Clone Stamp and Healing Brush—allow fine‑tuned cleanup if the moiré is severe.
Channel‑Based Repair
For persistent, color‑shifting moiré:
- Duplicate the Hue/Saturation channel and isolate the rainbow‑like band using a selection tool.
- Use the Clone Stamp or Healing Brush on the selected region to blend the colors.
- Adjust the Hue and Saturation sliders to match the surrounding tones.
Moiré FAQ
What Is Moiré in Photography?
It’s a visual artifact where the sensor’s pixel grid misinterprets a fine pattern, producing a secondary, often colorful, interference pattern.
Can Moiré Occur in Video?
Yes. Similar aliasing can happen when a camera’s frame rate or sensor resolution conflicts with a repeating pattern, leading to a flickering, wavy effect.
How Do I Avoid It?
Use the techniques above—adjust distance, aperture, focus, and angle. If the subject is unavoidable, consider post‑processing methods.
What Is Color Moiré?
Color moiré is a subset where the misinterpretation of color values creates a rainbow or oily appearance. It’s more common on lower‑end sensors but can appear on high‑end bodies if the pattern is too fine.
Is There a Quick Lightroom Fix?
Lightroom’s Adjustment Brush offers a quick way to reduce moiré, but for complex artifacts, Photoshop’s more advanced tools provide a cleaner solution.
Conclusion
While moiré can be frustrating, understanding its cause allows you to preempt it with simple in‑camera adjustments and, if necessary, clean it up efficiently in post‑processing. With these strategies, you’ll preserve the sharpness and integrity of every shot.
Roger Gilbertson / CC BY-SA 2.0
"Moiré" by XoMEoX / CC BY 2.0
"I want Moiré!" by mikemol / CC BY 2.0