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CMOS Rolling Shutter Artifacts Explained: What They Are and How to Fix Them
Created on 11.12
If you’ve ever captured a video of a fast-moving car, panned your camera quickly across a landscape, or filmed under fluorescent lights, you might have noticed strange distortions: tilted buildings, wobbly objects, or flickering bands. These aren’t mistakes in your camera—they’re CMOS rolling shutter artifacts, a common phenomenon in most modern cameras (from smartphones to DSLRs). In this guide, we’ll break down what rolling shutter is, why these artifacts happen, how to spot them, and most importantly, how to avoid or fix them. Whether you’re a content creator, vlogger, or casual photographer, understanding rolling shutter will help you capture sharper, more professional-looking footage.
What Is CMOS Rolling Shutter, Anyway?
To understand rolling shutter artifacts, you first need to know how a CMOS (Complementary Metal-Oxide-Semiconductor) sensor captures images. Unlike older CCD (Charge-Coupled Device) sensors, which read all pixels at once, CMOS sensors use a “rolling” method to record data.
Here’s a simplified breakdown:
1. The sensor starts by exposing and reading the top row of pixels.
2. Once the top row is done, it moves down to the next row, and so on—like a scanner moving across a document.
3. By the time the sensor finishes reading the bottom row, the top row was captured a few milliseconds earlier.
This delay between reading the top and bottom rows is key. When the camera or subject moves during that tiny window, the image gets distorted.
Rolling Shutter vs. Global Shutter: What’s the Difference?
You might hear “global shutter” mentioned alongside rolling shutter—and for good reason. Global shutter is the opposite of rolling shutter, and it avoids most artifacts. Here’s a quick comparison to clarify:
Feature | CMOS Rolling Shutter | Global Shutter |
How it works | Reads pixels row-by-row (top to bottom). | Reads all pixels simultaneously. |
Delay between rows | Milliseconds (causes distortion). | None (no distortion). |
Cost & size | Cheaper, smaller (used in most consumer cams). | More expensive, bulkier (used in pro gear). |
Common use cases | Smartphones, DSLRs, action cameras. | Cinema cameras, security cameras, drones. |
Most consumer devices use rolling shutter because it’s more affordable and compact. The tradeoff? Those annoying artifacts we’re about to explain.
The 4 Most Common CMOS Rolling Shutter Artifacts
Rolling shutter artifacts manifest in different ways, depending on what’s moving (the camera or the subject) and the environment. Below are the four most frequent issues, with examples to help you recognize them.
1. Jello Effect (Wobble)
The jello effect is the most well-known rolling shutter artifact. It happens when the camera moves quickly (e.g., walking while filming, panning fast) or vibrates (e.g., filming from a moving bike).
• What it looks like: Straight lines (like a horizon, doorframe, or lamp post) bend or “wave” like jello. For example, if you run while filming a building, the walls might curve inward or outward.
• Why it happens: As the camera moves up/down or left/right, the sensor reads rows of pixels at different times. By the time it gets to the bottom row, the camera has shifted position—so the bottom of the image is aligned differently than the top.
• Common scenario: Filming a concert while walking through the crowd, or using a smartphone to record a moving car from the sidewalk.
2. Skew (Tilt)
Skew (also called “slant” or “tilt”) occurs when a fast-moving subject crosses the frame, and the camera stays still.
• What it looks like: The subject appears tilted or slanted, even if it’s supposed to be straight. For example, a speeding train might look like it’s leaning to one side, or a person running past the camera might have a tilted torso.
• Why it happens: The subject moves so quickly that by the time the sensor reads the bottom row of pixels, the subject has shifted to the left or right. This creates a mismatch between the top and bottom of the subject.
• Common scenario: Filming a race car zooming past, or a bird flying quickly across the sky.
3. Wobble (From Fast Camera Rotation)
This is a specific type of jello effect caused by rotating the camera quickly (e.g., spinning in a circle while filming, or tilting the camera up/down fast).
• What it looks like: The entire frame “wobbles” or distorts, making stationary objects (like trees or buildings) appear to lean or spin. For example, if you quickly tilt your phone up to film a skyscraper, the top of the building might lag behind the bottom.
• Why it happens: Rotating the camera changes its angle between reading the top and bottom rows. The sensor can’t keep up with the rotation, so the image gets stretched or skewed.
• Common scenario: Vloggers quickly turning to show a new scene, or action camera footage from a skateboard trick (like a 360 spin).
4. Banding (Flicker)
Banding is unique because it’s caused by light sources, not movement. It happens when filming under lights that flicker at a specific frequency (even if you can’t see the flicker with your eyes).
• What it looks like: Horizontal, alternating light and dark bands that scroll up or down the frame. For example, filming a room with fluorescent lights might leave dark bands across the ceiling.
• Why it happens: Most indoor lights (fluorescent, LED, halogen) flicker at 50Hz or 60Hz (depending on your country’s electrical grid). The sensor’s rolling readout speed doesn’t match the light’s flicker frequency, so some rows are exposed to more light than others.
• Common scenario: Filming a conference room with fluorescent lights, or a kitchen with LED under-cabinet lights.
Why Do These Artifacts Happen? (The Science, Simplified)
You don’t need a degree in engineering to understand the root cause of rolling shutter artifacts—but a quick dive into the science will help you avoid them. The core issue is timing: the sensor doesn’t capture the entire image at the same moment.
Here are the two main factors that make artifacts worse:
1. Sensor Readout Speed: Slow readout speeds mean a longer delay between reading the top and bottom rows. Budget cameras (like older smartphones) often have slower readout speeds, so they’re more prone to jello effect or skew. Newer, high-end cameras (like flagship iPhones or mirrorless cameras) have faster readout speeds, which reduce artifacts.
2. Movement Speed: The faster the camera or subject moves, the more noticeable the distortion. A slow pan across a landscape might not cause issues, but a fast pan will. Similarly, a walking person might look normal, but a sprinter will likely appear skewed.
Lighting also plays a role in banding. As mentioned, 50Hz/60Hz lights flicker in sync with your electrical grid. If your camera’s frame rate (e.g., 30fps, 60fps) doesn’t align with that frequency, the sensor picks up the flicker as bands.
How to Avoid or Fix CMOS Rolling Shutter Artifacts
The good news is: you don’t need to buy a $10,000 global shutter camera to fix rolling shutter artifacts. Most issues can be solved with simple filming techniques or post-processing tools. Below are actionable steps for both prevention (while filming) and correction (after filming).
Part 1: Prevent Artifacts While Filming (The Best Approach)
Fixing artifacts in post is helpful, but preventing them during filming is always better—it saves time and results in higher-quality footage. Here’s what to do:
1. Slow Down Camera Movement: The #1 way to reduce jello effect or wobble is to move the camera more slowly. Avoid fast pans, tilts, or walks while filming. If you need to move, use a tripod, gimbal, or stabilizer—these tools keep the camera steady and reduce sudden movements.
2. Avoid Fast-Moving Subjects (Or Adjust Your Angle): If you’re filming a fast-moving subject (like a bike), position the camera so the subject moves parallel to the sensor’s readout direction (left to right, not up and down). This reduces skew. For example, film a bike riding horizontally across the frame instead of towards or away from the camera.
3. Match Frame Rate to Lighting Frequency: To fix banding, align your camera’s frame rate with your country’s electrical grid:
◦ If you’re in a 50Hz country (most of Europe, Asia, Africa): Use 25fps or 50fps.
◦ If you’re in a 60Hz country (US, Canada, Japan): Use 30fps or 60fps.
Most cameras have a “anti-flicker” setting that does this automatically—enable it if you see banding.
1. Use Natural Light (When Possible): Sunlight doesn’t flicker, so filming outdoors or near a window reduces banding entirely. If you must film indoors, use incandescent bulbs (they flicker less than LEDs or fluorescents) or add a diffuser to soften the light.
2. Choose a Camera with Fast Readout Speed: If you’re in the market for a new camera, look for models with “fast rolling shutter” or “global shutter-like” performance. Flagship smartphones (iPhone 15 Pro, Samsung Galaxy S24 Ultra) and mirrorless cameras (Sony A7S III, Canon EOS R5) have fast readout speeds that minimize artifacts.
Part 2: Fix Artifacts in Post-Processing (If You Already Filmed)
If you already have footage with rolling shutter artifacts, don’t delete it—you can fix most issues with video editing software. Below are the best tools and techniques:
Artifact | Tools to Use | How to Fix It |
Jello Effect | Adobe Premiere Pro, DaVinci Resolve, Final Cut Pro | Use the “Warp Stabilizer” (Premiere) or “Rolling Shutter Correction” (DaVinci) tool. These tools analyze the footage and straighten distorted lines. |
Skew | Same as above | The same stabilizer tools work for skew. For minor tilt, use the “Rotation” slider to straighten the subject. |
Banding | Adobe After Effects, DaVinci Resolve | Use a “Remove Flicker” filter (After Effects) or adjust the “Gamma” or “Exposure” to smooth out bands. For severe banding, crop the frame slightly to remove the worst bands. |
Pro Tip: For smartphone footage, apps like CapCut (free) or InShot have built-in stabilizer tools that work well for minor jello effect. For professional footage, DaVinci Resolve (free) is a great alternative to expensive software like Premiere Pro.
FAQ: Common Questions About CMOS Rolling Shutter Artifacts
Even with the above guide, you might still have questions. Below are answers to the most frequently asked questions about rolling shutter:
1. Can rolling shutter artifacts be completely eliminated?
No—unless you use a global shutter camera. But with fast readout speeds, steady filming, and post-processing, you can reduce artifacts to the point where they’re unnoticeable.
2. Is rolling shutter worse in low light?
Yes, sometimes. In low light, cameras use longer exposure times to capture more light. This means the sensor takes longer to read each row, increasing the delay between the top and bottom rows. The result? More noticeable jello effect or skew.
3. Do action cameras (like GoPros) have worse rolling shutter?
Older action cameras did, but newer models (like the GoPro Hero 12) have fast readout speeds and built-in “HyperSmooth” stabilization that minimizes artifacts. However, action cameras are often used in high-movement scenarios (surfing, skiing), so artifacts can still happen if you move the camera too fast.
4. Why don’t my photos have rolling shutter artifacts?
Photos are captured in a single moment—even by a rolling shutter sensor. The sensor exposes all rows at the same time (for a photo) and then reads them row-by-row. Since the exposure is simultaneous, there’s no time for movement to cause distortion. Rolling shutter only affects video, where the sensor is capturing multiple frames per second.
Conclusion
CMOS rolling shutter artifacts are a common annoyance, but they’re not a death sentence for your footage. By understanding what causes them—timing delays between pixel rows—and using the right techniques (slow camera movement, stabilizers, post-processing), you can capture clean, professional-looking video.
Remember: you don’t need expensive gear to fix rolling shutter. Even a smartphone can produce great footage if you follow the tips in this guide. The next time you film, keep an eye out for jello effect or banding, and use the prevention steps to avoid them. If you do end up with artifacts, post-processing tools like DaVinci Resolve or Premiere Pro can save the day.
Have you dealt with rolling shutter artifacts in your footage? Share your experience in the comments below—we’d love to hear how you fixed them!
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