Any tips for repairing these artefacts?

[spyros78]

Hi all,

not sure whether this is the right place for this thread but please feel free to move it if needed.

I shot a short film a few years ago on Hi8. The quality is pretty bad but its got sentimental value to me :).

I have tried the BlockOverlap filter for AviSynth which seems to do magic. I am not sure whereabouts in the scipt I should deInterlace however, the scripts does work fine.

The reason I'm posting is because I also want to get rid a green vertical line on the right hand side of my frame and a horizontal at the bottom. (I guess they are caused by the heads of my camera? - could you please tell me how they are called so that I can find some information?). I am thinking of trimming and resizing back to 720x576 but I am hoping there is an alternative way.

Please see the attached frames and let me know what improvements you think I can make.

ps:The framegrabs are without using BlockOverlap.

Many Thanks!

[Boulder]

You can use LetterBox to hide the stuff you want, also Crop+AddBorders is one option. For processing interlaced material, use the search. The issue's been discussed quite a lot.

[spyros78]

Thanks Boulder,

I'll try your suggestions today. However, do you know what causes the shown artefacts and how they're called?

Many thanks!

[Rozen Detective]

If you don't want to crop off the corrupted borders, you could try replacing the chroma with that of their neighbouring areas.

# Replace chroma of specified border bars with chroma from lines/rows next to it.
function FakeChroma (clip c, int "top", int "bottom", int "left", int "right")
{
top = default(top, 0) # lines from the top
bottom = default(bottom, 0) # lines from the bottom
left = default(left, 0) # rows from the left
right = default(right, 0) # rows from the right

tline = top != 0 ? c.Crop(0, top + 2, c.width, 4).BilinearResize(c.width, top).FlipVertical() : 0
c = top != 0 ? Overlay(c, tline, mode="chroma") : c

bline = bottom != 0 ? c.Crop(0, c.height - bottom - 4, c.width, 4).BilinearResize(c.width, bottom).FlipVertical() : 0
c = bottom != 0 ? Overlay(c, bline, y=(c.height - bottom), mode="chroma") : c

lline = left != 0 ? c.Crop(left, 0, 4, c.height).BilinearResize(left, c.height).FlipHorizontal() : 0
c = left != 0 ? Overlay(c, lline, mode="chroma") : c

rline = right != 0 ? c.Crop(c.width - right - 4, 0, 4, c.height).BilinearResize(right, c.height).FlipHorizontal() : 0
c = right != 0 ? Overlay(c, rline, x=(c.width - right), mode="chroma") : c

return c
}

FakeChroma(top = 16, left = 16, bottom = 16, right = 24)

Of course, it is not perfect. Seems to work somewhat nicely, though:
http://img297.imageshack.us/img297/9634/fake1ot4.th.png (http://img297.imageshack.us/my.php?image=fake1ot4.png) http://img404.imageshack.us/img404/5153/fake2pj2.th.png (http://img404.imageshack.us/my.php?image=fake2pj2.png)

[Boulder]

However, do you know what causes the shown artefacts and how they're called?
The crap at the bottom is head switching noise, I guess the one on the right has something to do with the limitations of the tape. Pretty much every tape I've captured has had a similar area on either the left or right side.

[prof_unto]

If I were you, I wont resizing the video because I believe those artefacts will not shown due to TV Overscan (CRT TV)