How to fix weird exposure / colorbalance artifacts from source video?

Hey there

I recently played around in fcpx with the stabilizing feature and prior to this I noticed in my recent source video some kind of lighting/color balance/exposure weird artifacts / flicker/ flashes that shows up before any editing is done at all and I can see it for example when looking at the clip via quick time prior to importing it into fcpx. It shows up in the clips when going from one room to another.

I also noticed when trying to stabilize that footage in fcpx; all options to stabilize except inertia converts these light / colorbalance errors into even more weird hickups that makes the whole frame to jump really weird.

While there are plenty of tutorials on how to fix various constant flickering that is caused by framrate problems I have no idea what to call this when looking for a solution to fix it in the editing or preferably to prevent it in the first place.

Gear used:
Sony A7rII 100fps 720p original setting on camera, XAVC S HD
Extreme pro 280mb/s sandisk
FE 1.4 35 lens
Both lens and camera have the latest firmware and card is properly forrmatted and the card database did not report any errors when I checked via the camera self check in the sony menu.

I am aware about the limitations regarding software stabilizing and that it sometimes introduce visual artifacts and I have already ordered a stabilizing unit to prevent as much camera shake as I can in the future but I feel a bit worried about these strange flickering-pops showing up in some more important case in the future and as I see it now I dont have any way to prevent it with any new gear.

I guess I can set a fixed white balance and exposure for important jobs but sometimes it´s not a very ideal option especially when I want to move from one light scene to another in the same shot.

Anyone with some thoughts? why am I getting this "light-pops"?
Is this a video codec artifact?
Is it because I move the camera to fast?
Is is a color balance error where the camera gets confused?
Is it something else?
Whatever the camera gets confused about I would assume any Sony engineer would want this kind of changes in color balance or exposure to appear gradually and not at all like this where the light just pops this quick.

Links below are lower resolution clips but the artifact can be seen very easy.

The first link is the unedited footage and the rest is with different fcpx stabilizing alternatives.

www.videosprout.com/video?id=0f18e66b-a8...1c-9ae3-a42795618b60

www.videosprout.com/video?id=69999a84-1f...33-8ae4-773605947ad5

www.videosprout.com/video?id=ced85170-9d...2b-84cd-ce26949d417f

www.videosprout.com/video?id=e27e0c45-22...b2-8be9-292db3cd05ec

You have some automatic settings turned on in your camera. Auto exposure, auto white balance, you want all of that turned OFF for editing. If you really are shooting 100fps it will exaggerate it even more. And yes, that can cause stabilization and color grading issues. I'm sure others have better ideas, but I'd blade that clip at every instance of the camera changing its internal settings, then stabilize.

I can't see your video from behind our corporate firewall so I'm safely assuming Ben recognizes camera's auto settings artifacts. His suggestion to disable all automatic settings "for editing" probably should read, "disable all automatic exposure and white balance adjustment settings forever and be sure you know how to set up the camera for manual exposures under all operating and shooting conditions."

In my own defense, I said to disable those, for the purpose of editing, but I never said to turn them back on. But yes, Bogiesan is correct, NEVER use automatic settings on a camera. EVER. Unless it is a cat video you're just throwing unedited onto YouTube.

Wright wrote: ...some kind of lighting/color balance/exposure weird artifacts / flicker/ flashes that shows up before any editing is done...when trying to stabilize that footage in fcpx; all options to stabilize except inertia converts these light / colorbalance errors into even more weird hickups that makes the whole frame to jump really weird. ...I have no idea what to call this when looking for a solution to fix it in the editing or preferably to prevent it in the first place....Sony A7rII 100fps 720p original setting on camera, XAVC S HD...FE 1.4 35 lens....I can set a fixed white balance and exposure for important jobs but sometimes it´s not a very ideal option especially when I want to move from one light scene to another in the same shot...

I have an A7RII and have shot hundreds of hours of documentary video on it. I think you are looking at two separate issues:

(1) Exposure stepping when you cross the room threshold: On many cameras (including the 5D Mark III, A7RII, DJI Phantom series) using auto exposure may cause a discrete jump or step in the exposure under changing lighting conditions. On the A7RII I normally don't notice it if using manual exposure and auto ISO. However on some cameras (depending on settings) it is severe. I recently edited some old footage from a Nikon D300S and the stepping was so severe I had to heavily keyframe exposure correction, which was tedious.

Were you in manual exposure and auto ISO, full auto or what? With DSLR video you normally want the shutter speed fixed at 2x the frame rate, which would be about 1/200th for 100 fps (normally 1/60th for 30 fps) . Usually you want aperture fixed based on artistic preference, which only leaves ISO to balance the exposure.

Fortunately the A7RII can shoot video in manual exposure but with auto ISO enabled. On a scripted narrative or blocked out shot, using manual ISO is probably better but for documentary run and gun stuff using auto ISO may be required. Likewise with white balance. Manual is best but for moving shots in changing lighting auto is better than a severely mis-balanced shot.

Always closely evaluate test footage in representative conditions before deciding on a frame rate. Often using a higher frame rate can degrade image quality or add noise. It's sometimes better to use a lower frame rate and higher resolution. The A7RII in particular delivers much better low light 4k video in Super35 crop mode than in full frame mode. Unfortunately that makes getting a wide shot more difficult.

(2) The jerk going through the door threshold is likely a stabilization artifact unrelated to the exposure stepping. Stabilizers are often fooled by rapid scene changes like this. You can try different stabilizers but it can still happen. Besides the FCPX stabilizer (which is quite good) I also use Crumplepop's Better Stabilizer: www.crumplepop.com/fcpx-premiere-stabili...in-betterstabilizer/ also CoreMelt's Lock & Load: coremelt.com/products/lock-and-load-x.html The best one I ever used (on Windows) was ProDAD Mercalli. It is available for Mac but only as a stand alone utility not an FCPX plugin: www.prodad.com/Video-Stabilization-for-P...-Ins-29800,l-us.html

In general instead of trying to stabilize a big camera like the A7RII it might be more effective to use a DJI Osmo X3. If used with the optional Z-axis arm, you can run across a field and have pretty good results: a.co/jk4Mi8r

My crew has several GlideCams including the big X10 vest but often the little Osmo is good enough. It is a lot more convenient than balancing and tweaking a big GlideCam or SteadiCam. glidecam.com/product-x-10

OTOH there are some pretty nice 3-axis brushless gimbals so those are also options. But if the Z-axis arm was available for the Osmo X5 we'd probably use that 95% of the time: fstoppers.com/gear/dji-osmo-x5-ultimate-steadicam-system-131453

Thanks for all the helping comments, really appreciated!

I tried today in the same rooms with manual mode, 50fps, 1/50ss, iso800 fixed color balance. No strange artifacts and no unnatural framejumping, just some of the expected vibrations from going handheld. I am aware that perhaps I am using unnecessary rapid movement in the tests and perhaps those manual settings should be 1/100 50fps and some other iso value to better smooth out motion?

By the way I got a zhiyun crane today and it lowered the visible vibration from the hands further and also levels the camera nicely. As you pointed out I can see that my iphone 6 does a slightly *better* job in terms of delivering a bit smoother movement compared to the more expensive sony camera with that extra gimbal setup but I guess that´s because the sony needs to manage more pixels and a bigger frame + that the lower bandwith from the iphone in this dim scene and extra noise makes the iphone´s video look more fluid.

But ok so now I think I can figure out the part about exposure and color balance and also aim for manual focus to prevent any kind of focus breathing etc.. but still I am a bit confused about the framrate vs shutterspeed stuff.
There is this saying that you smooth out movement when using lower framerate, like 25fps vs 50fps etc. but I often feel the opposite, that it seems like when somebody walks across the frame, the body flickers and stutters from left to right compared to other clips in higher fps.
I filmed a group of people recently doing some group-workout stuff. I used 25fps and while I could absolutely done a better job holding my camera more steady, but looking at the people running and jumping there I noticed so much information was gone in their visual movements so when trying to fix that in the fcpx stabilizer / "Better Stabilizer for Final Cut Pro X" or "Lock and Load X – coremelt" it just made most of the timeline look artificial and wobbly.

Perhaps I should film in like 50fps to have as much info as possible for stabilizing / frame-blending, and then after this reduce to i.e. 24fps to make the stabilizing and movement be as easy on the eyes as I can?

"...but still I am a bit confused about the framrate vs shutterspeed stuff."

Very easy. To start, remember that each frame of video is not instantaneous, each has a duration in time. 25fps means each frame lasts 1/25 of a second. 50fps means each frame will last 1/50 of a second. Zoom in as close as you can to and FCPX timeline and you'll see the playhead, followed by a duration of gray after it in the timecode ruler. That's the duration of that single frame in time. Thus a few things happen, it's all physics.

Faster frame rates tend to have less motion blur, as the shutter is open for a shorter amount of time, catch less light. Slower shutters speeds, the shutter is open longer, more motion blur (or smearing) is introduced, but you get a slightly brighter image (more light).

Fast fps = less light/darker image, less time open/sharper image.
Slow fps= more light/brighter image, more time open/more blurred image.

Also, since a slower frame rate flashes fewer frames in front of your eyes per second, faster movement will be have more stutter. 25fps can only relay that much data to your eyes. Only 25 frames worth of data.

Faster frame rate flashes more frames per second, faster movement will be more smooth. 50fps relays more detail about movement to your eyes. 50 frames worth of data.

Say you're shooting stop-motion animation (claymation). If you only have 25 shots to create one second of film, compared to 50 shots, you have only 25 positions that model can be in. 50fps gives you 50 positions that model can be in to express one second of motion. So at 50fps you get more detailed motion, 25fps less detailed motion.

So how many frames there are to give you eyes data about the movement per second, the amount of light hitting the camera's sensor, the duration that shutter is open, all come in to play.

So at slower frame rates, you may want to stop down the shutter to not open up as much. Faster frame rates, open that shutter up to get more light in for a brighter, clearer image.

Hope that helps. And most of all, experiment with different settings on the same shots over and over. You'll figure out that specific camera's sweet spots pretty quickly.

Thanks, yep I basically understand most of that.
What I think my eyes react negatively to the most is this erratic jumpy stuttering stuff I see in some videoes and it is usually not what I take as motion blur. Motion blur can often make the video look fluid if I am trying to get that kind of style and I dont mind that usually.

But it seems sometimes it depends on player / hardware where the video is played on.

Take this example and make sure to set it to full hd quality 60fps.



As this guy mentions in the description I tried on my mac with latest browsers and operating system. I have a 2gb videocard (2,5 GHz Intel Core i7, 16gb ram) so my machine should at least be able to play hd video in 60fps.
In chrome that video looks awesome to my eyes in all of the panning that is done, really I have no complaints at all, even the last part looks nice with some consistant motionblur but no framejump or stutter whatsoever and I run this in full screen.
But then when I open the same link in firefox and safari the image jumps/ stutters really bad sideways every other 5-10 frames (or whatever the interval is) and I dont know if you see it but that is not motion blur at all, looks more like the player can´t handle the stream correct or is it something else?

This seems a bit like when people in the photo world post perfectly colorbalanced images to the web and shows to others which usually do not have calibrated screens
Any ideas on how to prevent this video artifact if I want to show something I really spent time on and carefully shot with high framerate nice gimballs and all that and want the viewers to see the same that I see? Only upload to vimeo or any other trix?
It seems kind of lame to expect everybody to expand and read the "more info" box where I say "hey you need to use chrome otherwise it kinda sucks"

Wright wrote: ....In chrome that video looks awesome to my eyes in all of the panning that is done...
But then when I open the same link in firefox and safari the image jumps/ stutters really bad sideways every other 5-10 frames...looks more like the player can´t handle the stream correct or is it something else?....

I tried it on both Chrome and Safari on my 2015 top-spec iMac 27 also on Chrome on my Windows PC which has a 3.8Ghz i7-875K and GTX-660 -- pretty old. I don't really see any difference.

Keep in mind that faster frame rates aren't always better, and not because of whether 24 fps is more "cinematic". Rather in the real world using real sensors there are often tradeoffs in resolution, noise, dynamic range, etc. at higher frame rates. With your specific camera and post processing, you have to test each frame rate for representative composition, camera and subject motion. Then you pick whichever one comes closest to meeting your preferences while minimizing tradeoffs.

However panning is often problematic and requires constant awareness of limits based on your camera, sensor, frame rate, focal length, angular motion, distance to subject, etc. This page from Red Cinema discusses some issues and guidelines: www.red.com/learn/red-101/camera-panning-speed

Another complication is if the source material is manipulated between two non-multiple frame rates like 24 and 30 or 24 and 60, or vice-versa. There are various conversion pathways, and there is ongoing research to improve these: www.tvtechnology.com/media-systems/0191/...te-conversion/267315

In some cases you can reduce frame judder by using optical flow smoothing which is a retiming option built into FCPX. However optical flow has its own tradeoffs and possible risk of artifacts.

Re video appearance after upload to a web site, this adds yet more uncertainty and things you must test. I usually test on both Mac and PC using VLC, Media Player and Quicktime Player and after upload to both Youtube and Vimeo using Chrome, FireFox, Safari, Edge and IE.

Yet another complication is newer TVs, monitors and even playback software on computers which use motion interpolation. Unless you know the exact behavior of the playback chain you can never be certain what it's showing you. A good example of this is Quicktime Player which sometimes performs deinterlacing on 60i material, and sometimes not, based on what's in the video header.

Hi
Thanks for the reply, as I guessed, showing video on the web introduces a lot of things to consider.
Sorry about the link, that guy posted 2 videos with 24 and 60fps and I apparently linked to the 24fps version.

The one I was supposed to reference to was this one:


Forward to 0:26 (where it says medium speed inside the videoframe) and from what I can see in chrome the panning is really fluid and more choppy on safari or firefox. Perhaps it´s something specific to my machine, I have no idea but either way as you say this seems to be perhaps something related to i.e. the codec sent to each browser since the video obviously can be seen in flawless stream on chrome at least for me.