What causes the dark halo around bright spots on old video?

[brassplyer]

I'm sure you've seen it, pretty much on all old video where this dark halo appears when the subject passes some threshold of brightness. Something to do with saturation of the equipment or the tape?

Why does it appear dark, and what's different about modern gear that doesn't do this?

[budwzr]

That's analog, and now we're into digital.

[JVRaines]

That's analog, and now we're into digital.

Brilliantly helpful reply.

The dark halo is an artifact present in image orthicon video pickup tubes used until the mid-1960s. Very bright areas cause a cascade of electrons from the sensor plate that overwhelm the collection mesh. They fall back to the scanning target, neutralizing positive charges, which causes the "splashed" area to be read as darkness.

A nickname for this video tube was "Immy" or "Emmy." The television awards are named after it.

[jagabo]

Those are oversharpening halos. Usually from VHS.

[budwzr]

That's analog, and now we're into digital.

Brilliantly helpful reply.

Well, sometimes the OP needs a wakeup call to get into the 21st century.

[pandy]

Those are oversharpening halos. Usually from VHS.

Look at the edges - mostly trailing edge is affected significantly so JVRaines is closer to root cause (but it doesn't mean that video was not artificially sharpened and there is no sharpening halos). There can be also other explanation - to slow amplifier (slew rate - for large signal it can be saturated and provide similar distortion).
Anyway it looks more like common distortion to analog processing and perhaps only more emphasised by digitalization.

[JVRaines]

Those are oversharpening halos. Usually from VHS.

Look at the edges - mostly trailing edge is affected significantly so JVRaines is closer to root cause (but it doesn't mean that video was not artificially sharpened and there is no sharpening halos). There can be also other explanation - to slow amplifier (slew rate - for large signal it can be saturated and provide similar distortion).
Anyway it looks more like common distortion to analog processing and perhaps only more emphasised by digitalization.

Yes, the image has been oversharpened. But that is not what the OP is talking about. The OP is referring to the large dark areas surrounding specular highlights on the metallic instruments. These artifacts originated decades ago when the scene was lensed by studio television cameras.


[Attachment 45946 - Click to enlarge]

[brassplyer]

Well, sometimes the OP needs a wakeup call to get into the 21st century.

That's what my windup alarm clock is for.