Recovering blown highlights

[Mr Chris]

I've been sent a video with badly blown highlights (not my capture, tape long gone, unfortunately), and I'm trying to fix it up the best I can, but I'm not really getting anywhere with my usual methods. I accept that a lot of detail is gone forever, but what are my best options for at the very least improving matters?

I've attached some screenshots and a representative sample from the much longer video - what techniques would you use to get it the best it can possibly be from such an iffy source?


[Attachment 79465 - Click to enlarge]

[Attachment 79467 - Click to enlarge]

[Attachment 79468 - Click to enlarge]

Just as an added aside, what could cause the highlights to blow so badly? I'm pretty sure this is straight from a DVD recorder and hasn't been processed. The chroma looks okay, but the luma seems to have rocketed off the scale. I'm just trying to understand what went wrong in the first place.

[Sharc]

Just as an added aside, what could cause the highlights to blow so badly?

- Improper Proc-amp or video levels settings during capture
- Wrong level conversion (expansion) applied, like limited (TV) to full range (PC)
- Poor capture device
- Something wrong with the DVD recorder (unlikely)
- Improper camera settings (problem would have been baked onto the tape)
- a combination of above ....

There is no way in recovering clipped brights. Maybe a little improvement by tweaking the levels (Avisynth, NLE or similar) should be doable.

[jagabo]

You can pull a little detail out of the brights. Here I've done so with AviSynth:

LWLibavVideoSource("sample.mpg") 
StackHorizontal(last, ColorYUV(gain_y=-20, off_y=-4))
TurnRight().Histogram().TurnLeft()

[Attachment 79471 - Click to enlarge]

The snow isn't completely blown out so you get a little more detail there. But in the kitchen scene the door is completely blown out so there's still no detail there. You can see a little more detail in other bright parts of the picture. Like the plate in the lower left corner:


[Attachment 79473 - Click to enlarge]

Any program that lets you adjust levels in YUV should let you do this.

[Mr Chris]

Thank you both very much.

You can pull a little detail out of the brights. Here I've done so with AviSynth:

That's a lot more detail than I was managing to get out of the brights in Premiere, so that's encouraging. A definite improvement - thanks.