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Best way to blur background behind a subject in motion in a video?
With a lot of pictures, I can easily blur out or mask out the background while only leaving the person in clear sight (this is post-editing, I don’t mean during filming).
But with video, I’m not sure if it can be done? I know how to roughly mask out the background I want blurred while leaving the moving person in clear focus, but the masking doesn’t move…it’s fixed so if the moving person walks slightly or waves off the clear section, it’s easily seen when their hand or body gets cut off into the blurred masked background.
Is there any better way to mask out / blur a background behind someone who is in motion in a recorded video (obviously I didn’t use a green screen during recording). Sometimes I’ve seen for example in sports clips an athlete in motion like going for dunk or running over a hurdle but the entire background was changed into something else as if they somehow extracted just the moving person from the original video and put a different background….. does anyone know how I can do that? I’m using Sony Vegas 12.
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7 Replies
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There is no easy way of achieving this in Vegas, As you found out masking
is the solution, but very time consuming, as you have to animate the mask
to fit the subject movements frame by frame.
Other tools are out there however to make such a process slightly easier.Steve Rhoden (Cow Leader)
Film Maker & VFX Artist.
Owner of Filmex Creative Media.
Samples of my Work and Company can be seen here:
https://www.facebook.com/FilmexCreativeMedia -
Thanks for the reply. So the ones I see on tv where they took actual sports clips and somehow extracted the subject in action putting a different background was done either frame by frame (weeks or months) or they used some sort of technology not available to the average consumer?
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The time honored way to blur the background of an image is with the camera’s lens. For example, a lens with a large aperture allows a relatively shallow depth of focus which will blur the background while keeping the subject sharply focused. So, what you see in a sports clip is probably produced by a combination of optics and videographer technique rather than digital manipulation.
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[Joe Bee] ” So the ones I see on tv where they took actual sports clips and somehow extracted the subject in action putting a different background was done either frame by frame (weeks or months) or they used some sort of technology not available to the average consumer?”
No Joe, this is a very common used method know as roto scoping or perhaps it is a combination of mat extractions. These are an advanced skill set learned and mastered by very very patient individuals. There are tools to assist in the process such as Imagineer Mocha or Fusion that has a robust tool set to assist in the process. These are but two tools. There are other tools preferred by roto artists but the names elude me at the moment.
A good roto artist can do the job in a relatively short time, A great deal depends on the amount of fine detail in the subject such as hair or sheer materials but these tools are available to anyone wishing to try their hand at the craft.
Your idea of drawing a mask around a still frame is correct and yes in order to mask out a moving subject the mask must be animated. This is know as a traveling mat.
Russ Froze -
[Bob Peterson] “The time honored way to blur the background”
It’s very true as Bob Perterson states that the depth of field effect is the time honored way to blur out the background in an image. If this is the desired effect then please let us know and someone or perhaps many will send information on how to achieve the desired goal.
Russ Froze -
A whole lot easier to shoot it that way if you can, lol
Steve Rhoden (Cow Leader)
Film Maker & VFX Artist.
Owner of Filmex Creative Media.
Samples of my Work and Company can be seen here:
https://www.facebook.com/FilmexCreativeMedia -
Thanks so much for the responses.
I’m using a Sony camcorder (PJ760). So, I should try and shoot my video adjusting the aperture so that the main subject is in focus and clear while the background is blurry?
Can this be achieved on auto setting or do I always have to manually adjust the settings while shooting? Sometimes, during live action (motion), it’s difficult to manually maintain focus…If I’m moving around, in and out, I’m constantly having to turn the jog dial to adjust the focus.
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