FCP Smoothcam and Optical Image Stabilisation

Hi all

Just a quick question. When I use Smoothcam in FCP I often get some weird image 'warping' for want of a better word. I thought this was only happening on underwater footage, but I've been doing some tests and found it happens topside too. Do you think that this is down to the use of Optical Image Stabilisation in camera?

Any ideas would be appreciated.

Cheers, Simon

Simon, what camera and post a pic if you can. Impossible to analyse from your description.

Hi Drew

I've uploaded some video as still frame grabs don't really show the problem that well.

At first look it appears to be a focus issue, but I've had it happen while using autofocus and fixed focus on various camcorders. This clip was from a V1 on maximum zoom and gives a really good example of what I'm talking about. I've had it happen through all zoom ranges though so I don't think the issue lies there. Nothing is apparently wrong with the footage before the smoothcam filter is applied, other than it being a bit shaky of course.

Hopefully you'll have some idea what's causing it!

Example

Cheers, Simon

Simon,

I use FCP 5 and use the smoothcam cam node from shake, I get the same effect if the clip is really shaky. If the movement is minor then it isn't that noticeable but big movements make it look like the screen is moving. I believe this is due to correction moving the frame in the x and y axis. Have a look at my PNG video, at the end there is a shot of a blue spotted ray which went through shake, it has a similar but lesser effect.

PNG Video

Does the warping depend on how much movement there was, i.e. lots of movement = more warp

Jon

Simon....there was no smooth cam filter in Studio 1 only in Studio 2 which is FCP 6. Have you tried using it in Motion? It might work out better for you there.

Steve B)

Simon

It's possibly a combination of a few things. The movement of your camera was too abrupt that it caused a blurry because your shutterspeed was too low. Smooth cam can compensate for the motion but not the actual image which is blurred. If you look at the original clip frame by frame you'll see it.

THEN throw in a little skewing from CMOS sensors and voila!

Simon

Load up some of the raw M2t and I will run it though EDIUS using Mercalli to see what results it gets.

Simon

It's possibly a combination of a few things. The movement of your camera was too abrupt that it caused a blurry because your shutterspeed was too low. Smooth cam can compensate for the motion but not the actual image which is blurred. If you look at the original clip frame by frame you'll see it.

THEN throw in a little skewing from CMOS sensors and voila!

I get the jumping also from time to time (I recall you mentioning the CMOS and the other elements n the past.) One thing that I found sometimes helps a bit is tweaking the settings down from the defaults, though it never seems to fully clear it up. In other words the bit of a glitch is usually still there.

I keep on meaning to do some A/Bing between Shake, FCP and Motion at some point to see if there are differences in there somewhere even though they should probably behave the same (the FCP and Motion are suppossed to be the same as the Shake but who knows.)

Have you found any tweaks that seem to work better?

Well the issue here isn't smoothcam but the original clip.

Motion blur cannot be compensated for. That is why I always suggest that people shoot at 1/60 or higher and take the noise hit. It's better than motion blurred images.

Another issue is the rotational axis that smoothcam has to compensate for. I don't have access to the original clip so I can't tell if smoothcam needs more tweaking in the rotation setting or if it's CMOS skew, which cannot be corrected.

The SmoothCam engine is pretty much the same. I don't use it much but Shake in my mind has better controls and tweaks, but the FCP 6 version has a more capable functionality with autozoom etc. I've asked before but can't remember what I was told about the plug-in and the port from Shake.

Doesn't matter really... the old addage of garbage in, garbage out applies to video as well.

I'm speaking in general and not about Simon's clip.

haha well the clip was garbage Drew - that's why I posted it!

I'm not at home now and wont be back until well into the new year, so unfortunately I can't upload a raw clip for comparison by other filters. The clip I posted was an extreme example - the shot was taken hand held at maximum zoom, so there was a lot of movement, but I've had it happen on clips where the camera as been as good as still and although the warping is not as apparent it is still definitely there if you look hard enough.

When I get home I'll try to post a variety of clips both before and after smoothcam has been applied to let people have a look at. The idea that I had was that somehow the optical image stabilization was 'smoothing out' any movement and then when the smoothcam filter was applied it wasn't allowing or couldn't allow for this in its calculations. I only recall ever getting this warping when image stabilization has been used in camera, although I can't guarantee that and would have to go and specially test for it to be 100% sure.

Cheers, Simon

Simon

OIS is applied BEFORE it is recorded to tape. It seeks to smooth out any motion there is. SmoothCam does the same thing by comparing pixels in ALL frames of the clip, choosing a subject and making sure it stays central.

If there isn't any movement, it won't compensate for it. So if OIS worked then SmoothCam will work too. Not sure what you are getting at?

I'm not sure either Drew as I'm not as technically savvy on camera workings as some people here. I just wondered if it could have been a combination of in camera image stabilization causing the image to warp slightly, which then only becomes visible and then apparent once all of the movement has been removed by smoothcam.

Cheers, Simon

If you are saying that SmoothCam cannot properly correct for motion, I'd say it's great but not perfect. However in your particular situation, it's a function of shutter speed and shaking. You have a few frames that were motion blurred and the warping is probably CMOS sensor skewing as you had the camera zoomed in and at 20X, CMOS rolling shutter effect is magnified as your camera motion is as well.

As I suggested earlier, look at your original clip frame by frame, if there is rolling shutter effect then adjust the SmoothCam settings higher to compensate. I'm quite certain that it's a combination of what I've said already.