How to Remove Stuck or Hot Pixels from Video Footage
One of the drawbacks to shooting movies with DSLRs is the problem of stuck pixels, also known as “hot” or “dead” pixels. If every pixel on a DSLR’s large CMOS sensor is essentially a bucket for catching light, out of the tens of millions of buckets (21 million in the case of the 5D Mark II), there are always going to be a few faulty ones. But whereas dead pixels are easy to remove from still images (and harder to detect), on video they stick out like a sore thumb. So — what to do if your otherwise beautiful footage is marred by one (or more) stuck pixels? Thankfully there are a number of solutions to removing dead pixels in post, using your software of choice. Included here are methods based on Final Cut Pro, Vegas, Aperture, and After Effects.
After Effects ships with a Wire Removal plug-in, which you can use to track the beginning and end point of a wire (e.g., if you’re doing a Kung-Fu movie and your actors are flying around Crouching Tiger, Hidden Dragon-style). This will also work to remove a hot pixel, if you set the two points very close together, and then you can save it and apply it to your footage in batches given the stuck pixel is in the same place. Here’s the process (it’s called CC Simple Wire Removal and is built into AE), from Hampton Road Studios
You can also try to use the Clone Stamp tool, which is what’s pictured above, but I find setting a target point separate from where the stuck pixel is creates less than ideal results. The Wire Removal tool works better in my experience.
On the plugin side of things, RE:Fill by RE:VisionFX looks like it might work, but it doesn’t explicitly mention dead pixel removal as a use for the plugin.
Final Cut Pro
There are a number of solutions to remove hot pixels using Final Cut Pro. Via this thread at Cinema5D I found out about video whiz Adam Wilt’s FXscript to remove dead pixels — exhaustive details of the process here. Long story short, you can download his custom script for free, unzip it, and drop the folder “AJW’s Filters” into /Library/Application Support/Final Cut Pro System Support/Plugins. Restart FCP, and:
Drop the filter on a clip you want to fix. Use the Location control to position the white square atop the area you want to mask, then uncheck “Use Test Color”. Fiddle with the trims, height, and width to properly mask the hotspot; you want the smallest mask possible that adequately covers the hot pixel and any of its side effects. Stepping through the clip for a few frames is useful to double-check things; toggling the mask on and off (and/or toggling the test color on and off) is useful to verify position and effect. You can also try using different pixel mask sources, in case the default “all four edges” blend causes a visible bump or blemish in the image. Once you’re happy, you’re done. If you have more clips from the same camera to mask, drag the filter to the Favorites bin in the Effects browser, and give it a descriptive name (like “pixel mask – upper left” and pixel mask – upper right” for the two instances we used for our two cameras).
In the comments of this post at Planet5d, Carl suggests The Repair-collection by CHV-Electronics, which features a plugin called, appropriately enough, Dead Pixel. The plugin costs $99 and also includes tools for dirt, dropout, and noise removal. If you’re going to be doing a lot of this stuff in FCP it’s definitely worth a look.
There is a complicated (but free) plugin written for the sole purpose of removing stuck pixels in Vegas here. These instructions will get you started, but be warned — you’re going to spend some quality time in Vegas if you’re using this plugin. “Download the plug in via the link below. Copy stuckvideopixelremover.dll to the folder where you store your other Sony Vegas plug ins. Register the DLL by opening a command prompt and executing the command “regsvr32 stuckvideopixelremover.dll” in the folder where you’ve put the DLL.” And that’s just the beginning…
If you have a lot of sensor dust1 on your image (and a lot of time on your hands) you can export sequential TIFFs to Aperture and use the batch controls to bring back footage from the dead. We could’ve used this on The West Side, but then again our hands were pretty full on that production, and it was supposed to be gritty anyway. Regardless, here’s an in-depth tutorial on using Aperture to remove sensor dust. While you can use the Spot & Patch tool to effectively remove dust, it does get a bit complicated if the dust is covering complicated imagery (as opposed to, say, the sky seen at left).
Have you run into problems with stuck pixels on your footage? Do you have other solutions to this all-too-frequent DSLR problem? Feel free to share in the comments!
- Persistent smudges instead of pinprick points. [↩]