When odd stripes and patterns appear in your images, this is called a moiré effect. This visual perception occurs when a fine pattern on your subject meshes with the pattern on the imaging chip of your camera, and you see a third separate pattern. (This happens to me a lot when I take a photo of my laptop screen). Moiré is an optical phenomenon that occurs when two patterns with similar frequencies interact with each other. This interference produces an unwanted pattern that can be visible in digital images, prints, and even textiles. In this article, we’ll take a closer look at what causes moiré, how to avoid it, and how to remove it.
What Causes Moiré?
Moiré is created by the interference of two patterns that have similar frequencies. For example, when a digital camera captures a pattern on a fabric or other textured surface, the pixels in the camera’s sensor can create their own pattern that interferes with the original pattern. This can cause the image to have a distorted appearance with visible waves or lines.
Moiré can also occur in printed materials, such as magazines or books, when the printing pattern interacts with the halftone pattern used to create the image. The result is a visible pattern that can detract from the overall quality of the image or text.
Video: How to Deal with Moiré: Take and Make Great Photography with Gavin Hoey
Because fewer cameras are now equipped with an anti-aliasing filter (they slightly blurred the photo and who wants a blurry photo?), you’ll see the moiré effect occurring more often these days, especially as a portrait or architectural photographer.
So, what causes the moiré effect, how can you spot it while you are shooting, and how can you avoid it? How do you fix it in post? In the following 11 minute video from Adorama TV, Gavin Hoey answers these questions about moiré as part of his Take and Make Great Photography series. As Gavin explains the moiré effect, when you combine the patterns in just the “right way, you’ll see a rainbowing or circular pattern” in your image.
To avoid it altogether, Gavin recommends you take a test shot, then zoom in to make sure you aren’t getting the effect. Gavin then gives three solutions to get rid of moiré if you happen to spot it in your image. But what happens if you miss it until you sit down in post? Gavin has a simple Photoshop/Lightroom fix.
How to Avoid Moiré
The best way to avoid moiré is to prevent the interaction of two patterns with similar frequencies. Here are some tips to avoid moiré:
- Adjust the angle of the camera or the subject. Changing the angle of the camera or the subject can help prevent the interaction of two patterns with similar frequencies.
- Use a different lens or aperture setting. Changing the lens or aperture setting can help reduce the amount of interference between the two patterns.
- Change the lighting or shooting conditions. Adjusting the lighting or shooting conditions can help reduce the amount of interference between the two patterns.
- Use a camera with an anti-aliasing filter. An anti-aliasing filter is designed to reduce moiré by blurring the image slightly, which helps prevent the interaction of two patterns with similar frequencies.
How to Remove Moiré in Photo Editing
If moiré is visible in an image, it can be removed using software tools or manual techniques. Here are some methods for removing moiré:
- Use software tools. Programs like Adobe Photoshop or Lightroom offer tools that can help remove moiré. These tools can desaturate or blur affected areas, or use algorithms to remove the unwanted pattern.
- Selective desaturation or blurring. Selective desaturation or blurring can be used to remove the unwanted pattern by blurring or desaturating the affected area.
- Manual removal. Manual removal involves using a cloning or healing brush to manually remove the unwanted pattern. This method can be time-consuming and requires a high level of skill.
Moiré can be a frustrating problem that affects the quality of digital images. However, by understanding what causes moiré and how to avoid it, we can take steps to prevent it from occurring. If moiré is present in an image, there are methods for removing it using software tools or manual techniques. By taking these steps, we can produce high-quality images and prints that are free of unwanted patterns and interference.