HDR video from VHS captures?
 

Just wondering -- has anyone here ever attempted to create an HDR video by capturing a VHS tape multiple times at different black/luma levels (using a proc amp, for example) and overlaying them to get more details out of under and over-exposed areas of the image?

I found a cool tutorial on how to do it with digital video using Adobe After Effects and an image processing program:


I'm thinking for analog captures, though, you could use a proc amp and actually do 3 separate video captures rather than extrapolating 3 exposure levels in post by adjusting the black/luma levels each time to create brighter and darker versions. (Obviously you'd have to accept the "weird" look that the process gives the video in exchange for being able to see detail in dark/light areas better). You'd also have to align the 3 clips to be synced down to the frame, which may be difficult.

No, I've never tried.

HDR is already demanding on a still image. I can't imagine what would happen when you give it 30 per second! It would clearly need post-process.

I bet it would give some wild effects. :cool:

You can do that with curves in sony vegas imo you just have to capture slightly brighter

I've thought of this, however there isn't any extra information to be found, in some cases. Let's say the VHS was recorded from a DVD, or a digitally mastered Laserdisc, in that case the source itself is only 8 bits and making 3 passes as you say can at best just make 3 copies with different contrast/brightness. There's filters to make an HDR look however.

The only case I thought you might get any real HDR is when the VHS was recorded from an old, true analog camera, which obviously has infinite range, however that range is limited by noise in some way.

There's one more advantage to this idea, in that the capture process probably isn't very linear, but "bowed", which is a typical shape resulting from the proc before the adc, and you could use the most linear portions of the curve in 3 passes to get a slightly better recording. I have tested that, and found my curve, and could get an extra bit out of it.