Fixing spotlight washout?

[kme06d]

I'm not sure if this is even possible, but I figured I'd ask anyway. I have a video of a live stage show and the video quality is great, until the spotlight comes on. There is some pretty bad spotlight washout when the camera has a wide shot of the stage. Is there anyway to fix this? I've got a couple of programs I'm using, the one I'm trying now is Sony Vegas Pro 9.0. Any help would be appreciated. Thanks!

[poisondeathray]

Usually not much you can do if it's blown out, but it depends on how "bad" it is. Sometimes you can improve it a little. Can you post a screenshot or sample ?

[kme06d]

I've attached a screenshot.

[poisondeathray]

From the screenshot, it doesn't look too promising...

What camera/format did you shoot with ? Some can shoot and retain information >235 in the "whiter than white" range (235-255) , and you can access these if you work in full range. But the spots that are pure white 255, are hopeless.

If it's only when the spotlight comes on, you could rotoscope the spotlight (basically mask out certain sections of frames), to limit your filtering to specific areas; if you apply to the entire frame , the "good parts" out of the spotlight will be adversely affected. I would do this in something like After Effects which allows you to apply feather masks

Would it be possible to upload a sample video clip ?

[kme06d]

I've uploaded a sample clip. I didn't shoot the video myself, so I don't know what camera was used.

[poisondeathray]

You can reduce the glare of the periphery, but the important details like face details are completely blown out in that sample. It looks like the actors are wearing white masks...

Was that the original video or was it recompressed with DivX ? What format was the original video?

The details are important, because you might have exacerbated the problem by converting to that to Divx

[kme06d]

The video that I received was in a .vob format. I'm not sure what the original video file was off the camera, and I don't know the person who shot it to ask them. I converted it to an .avi so that I could play it on my computer (that was the file that I attached).

[poisondeathray]

Sounds like a DVD recorder. Unlikely you will be able to salvage much, except dim the spotlight a bit, and recover a bit of detail in the clothing. The face details are blown out.

[kme06d]

Okay. Well...thank you for your help. I really appreciate it!

[edDV]

Several issues.

First the file you sent is scaled 0-255 with clipping at 255. The original camcorder file was probably scaled 16-255 (235 nominal white) so that probably has more bright white detail. get the original file.

Second, the camera is wrong for this type of shoot, or the spot was too bright. Use film which has wide exposure lattitude, or a Sony VX-2100 or better to get the "knee". The knee manages over-whites down into the 235-255 levels.

[edDV]

The file you posted can't be improved since the faces are clipped to 255.

You can play with levels and gamma to brighten the background but face detail is lost unless the original camcorder files are available.

[kme06d]

Thanks for the input. Unfortunately, this video is one that has been circulating by traders since it's release so there is no way I'd be able to find the original file. It looks as though the filmer was sitting on the balcony during the show, so when they shot straight ahead, all they picked up was the spotlight. I know from experience that that's about all you can see from up there anyway, so it's pretty accurate from reality. Just out of curiosity, why is it that the original video file can be altered to fix it, but not a copy? Would changing it to another format work better? I don't know much about video enhancement, so I'm still learning all this stuff.

[edDV]

Description of Sony "knee".

This is why the VX2100 or better is recommended for shooting stage plays. You still need to negotiate spot intensity with the stage manager after video tests. They either want a good video or they don't. Expect politics on the level of a wedding shoot.

http://pro.sony.com/bbsccms/assets/files/micro/xdcamex/solutions/Avoiding_Over-exposure.pdf

PS: the VX and PD series DV cams have a fixed knee function. To get adjustable knee you need to move up to the models described.

[edDV]

...why is it that the original video file can be altered to fix it, but not a copy? Would changing it to another format work better? I don't know much about video enhancement, so I'm still learning all this stuff.

Because someone, maybe you, converted the 16-255 original to 0-255 by mapping 16 to 0 and 235 to 255. That caused the original 236-255 to be clipped to 255.

It is a long shot but the original file may have more face detail in the 236-255 levels.

[kme06d]

oo. Is there a way to reverse the conversion so that we have something similar to the original file?

[edDV]

oo. Is there a way to reverse the conversion so that we have something similar to the original file?

No because the original white detail was tossed to the digital cutting room floor during conversion.

Another often used trick is to use blue or red gel spots. The camera is less sensitive to blue and red so the audience will see a brighter spot but the camera won't blow out as fast. All this needs testing in rehearsal.

[Gavino]

oo. Is there a way to reverse the conversion so that we have something similar to the original file?

Of course not.
Everything originally between 236 to 255 has become 255.
How could that be reversed? There is no way of knowing what the original value was for any 255 pixel.

[edDV]

This why when a stage play is scheduled for broadcast taping, the stage manager reports to the broadcast technical director by contract. TV gets the priority.

[jagabo]

Use DgIndex to export a short bit of your VOB file as an MPEG 2 elementary stream (M2V). That will be an exact copy of the MPEG 2 data in the VOB file (there's no telling what the conversion software may have done when you created the AVI file). Upload that and someone will be able to tell you if there is any hope of restoring a little bright detail.

[kme06d]

Use DgIndex to export a short bit of your VOB file as an MPEG 2 elementary stream (M2V). That will be an exact copy of the MPEG 2 data in the VOB file (there's no telling what the conversion software may have done when you created the AVI file). Upload that and someone will be able to tell you if there is any hope of restoring a little bright detail.

I just downloaded the software, but I'm not sure how to convert the file using it. Could you walk me through it?

[kme06d]

Nevermind, I got it. Here is the file.

[edDV]

The guy on the right has some facial detail left. Not much to work with. The other two are mostly clipped to white.



As said, the original camcoder file probably has 19 more levels in the whites above what we see here.

[jagabo]

Yes, the clamping (at Y=235) was done before the MPEG 2 file was made. There's only a little noise over 235. So there's no hope of restoring more detail in the washed out areas.

[kme06d]

Yes, the clamping (at Y=235) was done before the MPEG 2 file was made. There's only a little noise over 235. So there's no hope of restoring more detail in the washed out areas.

Okay. Thanks for the help! So does that mean that when the person took it off the camera, it changed the picture quality? (sorry, still trying to understand what exactly had happened)

[edDV]

Yes, the clamping (at Y=235) was done before the MPEG 2 file was made. There's only a little noise over 235. So there's no hope of restoring more detail in the washed out areas.

Okay. Thanks for the help! So does that mean that when the person took it off the camera, it changed the picture quality? (sorry, still trying to understand what exactly had happened)

It was poorly converted. This assumes the original camcorder was properly exposed (see Knee) but that probably wasn't the case.

The conversion took a 16 = black, 235 = nominal white with 236 to 255 whiter than white and sawed it off at 235.

235 became 255 and 16 became zero.

This is a common rookie mistake but it destroyed upper white detail. You need to go back to the camcorder file and do it right.

A more pro approach to this is to set lights within the camcorder exposure range. This should be done during rehearsal.

[kme06d]

Yes, the clamping (at Y=235) was done before the MPEG 2 file was made. There's only a little noise over 235. So there's no hope of restoring more detail in the washed out areas.

Okay. Thanks for the help! So does that mean that when the person took it off the camera, it changed the picture quality? (sorry, still trying to understand what exactly had happened)

It was poorly converted. This assumes the original camcorder was properly exposed (see Knee) but that probably wasn't the case.

The conversion took a 16 = black, 235 = nominal white with 236 to 255 whiter than white and sawed it off at 235.

235 became 255 and 16 became zero.

This is a common rookie mistake but it destroyed upper white detail. You need to go back to the camcorder file and do it right.

A more pro approach to this is to set lights within the camcorder exposure range. This should be done during rehearsal.

I see. Like a said, I didn't record the video so I don't have access the original file. I really appreciate everyone's input with this it was very informative!

[poisondeathray]

So does that mean that when the person took it off the camera, it changed the picture quality?

There are other problems than just being blown out. You have lots of aliasing (look for a bunch of "jaggies" or stair steppy edges) , I suspect whoever did the transfer did a poor job of deinterlacing or interlaced resizing (it shouldn't have been deinterlaced in the first place for DVD)