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Old August 16th, 2005, 02:51 AM   #1
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Shoot first DOF Post?

I googled here and there to see if any software solutions are availble for creating "depth of field" in post..?
this option seems to be possible with pictures in photoshop, could it be done with video?
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Old August 16th, 2005, 03:56 AM   #2
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Owen,

I've not seen any posts in this forum for software to perform DOF in post-production on video. This thread contains links to a couple of software programs that add depth to stills, so the workflow to get it done for video would be to serve individual frames, add the DOF tweak and then reassemble in video. In theory it could be done, I shudder to think of the time to do it and the chance to get a frame out of order or with slightly different tweak applied.

There are dozens of recommendations in the "Toward a Film Look Using DV" forum for producing better DOF in production (I know this isn't what you asked for, but wanted to make sure you knew that advice was available).
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Old August 16th, 2005, 05:33 AM   #3
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Old August 16th, 2005, 06:24 AM   #4
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Searching for DOF in the film look forum will point you in the right direction...

http://www.dvinfo.net/conf/showthread.php?t=40488
http://www.dvinfo.net/conf/showthread.php?t=44059
http://www.dvinfo.net/conf/showthread.php?t=12715
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Old August 16th, 2005, 09:51 AM   #5
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I tried this on a short I recently did. I found out that it was way to much work (for me anyway). I made a mask in Vegas of what I wanted in focus and then animated it for every frame. The animation has to be good though, or you can tell. Then apply a blurring filter to the background. Here is the result. I only have one second up, but I looped it. You can see I didn't pay enough attention under the chin.

It is a nice effect but way to time consuming. Also, there are some wide shots you will never be able to make look convincing.

http://media.putfile.com/DoF-Applied
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Old August 16th, 2005, 11:03 AM   #6
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1- Has anyone tried using difference keys to isolate the foreground subject?

2- If you do the animated masks method (using feathering on your mask), then it'll work. But, it is time-consuming and the area around the foreground subject's edges won't look out of focus.
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Old August 16th, 2005, 11:40 AM   #7
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Also, it will not work with transparent material. My verdict is: do not bother. It is hard enough to do this convincingly with stills... you stand no chance in video unless you use chroma key... and you do not want to do that with DV anyway. There are better ways to spend your resources then trying to emulate defocusing.
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Old August 16th, 2005, 01:34 PM   #8
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http://fxhome.com/support/tutorials/view.php?i=8

Once you know the trick, it becomes more easy.

If you wanna work fast, just import your finished project, and jump to the take were you want more depth. Nothing could be easier than this.
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Old August 17th, 2005, 02:36 AM   #9
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thanks for the links guys, didnt realise how complex it would be to dof in post.

maybe one day they will come up with an easy to use plugin that enables manual control over dof with assignable midi controllers? or maybe im talking nonsense..

thanks again, lovely community. :)
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Old August 18th, 2005, 10:56 AM   #10
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Quote:
Originally Posted by Roberto Lanczos
http://fxhome.com/support/tutorials/view.php?i=8

Once you know the trick, it becomes more easy.

If you wanna work fast, just import your finished project, and jump to the take were you want more depth. Nothing could be easier than this.
Yeah, it actually is pretty easy and not to time consuming - I've been doing this for a while now for a variety of projects (not live stuff obviously).

Be warned, it's a lot easier with a locked down tripod shot though, so don't bother if you're doing steady/handheld/whatever. I've found that most of the time the motion blur of the background more than makes up for a lack of DOF processing.
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Old August 25th, 2005, 08:44 PM   #11
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Automating synthetic shallow depth of field

The difficult thing must be to accurately identify which area of each frame should be kept sharp. The next problem would be how to grade the defocus of objects so that there is a gradual blurring of objects depending on how far they are from the focal plane.

This sort of thing is manageable by hand for stills. In video you need automation. Too simplistic an aproach will result in 3 flat planes: too close, in focus, and too far. Getting it right is not easy.

One approach would be to measure the sharpness of different areas of the image. This would allow a program to detect the existing blur due to objects not being perfectly in the plane of focus. Various synthetic artefacts could then be added according to this data to exagerate the shallowness of depth of field.

This would still require perfect focusing as when shooting 35mm, but with the added difficulty that the plane of focus is not nearly so obvious to the human eye in the raw image. This approach would probably work for 2/3" sensors but not 1/4".

Does anyone know how the plugins mentioned earlier in the thread choose what to keep sharp? Does anyone have raw and synthetic DoF clips of their own to show?

A different approach (for home built camera) would be to have a small low res camera some distance to the side. Ideally the second camera would share time code, certainly it should have the same frame rate, or a known fraction of the frame rate. Comparing the location of objects in both images would give a paralax range finder for every sub region of the frame.

Knowing the distance of every object would allow you to decide the distance and depth of focus in post. Such a paralax camera could be a 1/4" primary sensor with say a 1/10" phone camera set 3" to the side of the main lens.
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