motion artefacts

[AlanHK]

I have an old capture from videotape.

With any scenes with relatively fast movement there is a banding, comblike effect, as in the image -- see the hand in the centre and the cap.

What is this effect called?
Are there any filters that could improve this (detect, blur and then sharpen the affected regions, perhaps)?

Not knowing the terminology makes it hard to search for solutions.

[Guest]

That looks like the result of naive resizing without deinterlacing.

[AlanHK]

That looks like the result of naive resizing without deinterlacing.

Why would it be limited to moving objects then?

Whatever the cause, is there any way to make it less obvious?

[TheRyuu]

Why would it be limited to moving objects then?

Whatever the cause, is there any way to make it less obvious?

Thats exactly because of the resizing without deinterlacing. The interlacing artifacts appear on objects or people that are in motion.

[Guest]

Why would it be limited to moving objects then? Because that is where interlacing artifacts occur.

Whatever the cause, is there any way to make it less obvious? Are you trying to make a progressive result? If so, deinterlace the stream before you resize it.

If you are trying to keep it interlaced, then do a proper interlaced resize operation.

[AlanHK]

Because that is where interlacing artifacts occur.

Are you trying to make a progressive result? If so, deinterlace the stream before you resize it.

If you are trying to keep it interlaced, then do a proper interlaced resize operation.

The artefacts and the image have not been resized at all (by me); that's what I have to work with.

It's a TV capture from 1962, made by God knows what technology.

[Guest]

Then you're screwed.

[2Bdecided]

That's Steptoe and Son, isn't it?

Either:

A) It was filmed (with a film camera) from a 405-line TV screen. This would have been frame locked, and in this case it captured both fields. (Earlier versions of this technology captured one field and dropped the other).

B) It was replayed from an early domestic 405-line video tape on a 405-line TV, and a modern 625-line camera was pointed at that TV. There was no frame lock, and what was captured was quite random.

The Vidfire technique is designed to help with (A). On (A), the individual lines were usually blurred together via a technique called spot wobble. If you look at the Doctor Who Restoration team website and forum, you can read lots about all this.

What you have looks like (B). Some of the early Steptoe and Son episodes were recovered from early tapes made by the writers (Galton and Simpson). It's a shame that was reportedly the only copy that was made before the tapes became unplayable. Those original tapes would have been skip field recordings, storing only one out of two fields, but replaying it twice.

I don't know of a filter to help with this, but it's conceivable that one would be written. Unlikely, but not impossible.

Cheers,
David.

[xbox360]

Check this out, this might help !

http://www.compression.ru/video/old_film_recover/field_shift_en.html

[2Bdecided]

I think that filter requires lines to be preserved as, discrete lines (but in the wrong frame) - not filmed and blurred over several new lines.

It might be worth a try though. Thanks for the link.

Cheers,
David.

[scharfis_brain]

AlanHK, provide an unprocessed Sample.