Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > Capturing and Editing Video > VirtualDub, VDubMod & AviDemux

Reply
 
Thread Tools Search this Thread Display Modes
Old 27th February 2008, 23:10   #81  |  Link
Undead Sega
Registered User
 
Join Date: Oct 2007
Posts: 713
http://www.channeltv.co.uk/deshakers.gif

why do these distortions happen?

and what do you call them also?
Undead Sega is offline   Reply With Quote
Old 28th February 2008, 00:39   #82  |  Link
mustardman
Registered User
 
Join Date: Dec 2002
Location: Australia
Posts: 264
My guess would be the effect is caused by the distortions present at the edges of the lens. The distortion becomes worse the further away from the center of the image the 'target' is.
For a steady lens, this is of course not noticeable. However, if the lens moves around, and then the image is stabilised later, the distortion becomes very obvious (as you can see).
Think 'pincusion' effect with wide angle still (and video) cameras.

Is is particulary bad with cheaper lens, and is even present with more expensive lens. If you really don't want it, buy a 'hollywood' movie camera lens... but be prepared to walk away 20k poorer!

MM

PS: One way to minimise this effect with a "cheap" lens is to zoom in to the subject. Less of the glass is used, and the area in use is closer to the center. Only problem, if the camera is shaking to begin with, zooming in is going to make it a whole lot worse!
mustardman is offline   Reply With Quote
Old 28th February 2008, 00:50   #83  |  Link
scharfis_brain
brainless
 
scharfis_brain's Avatar
 
Join Date: Mar 2003
Location: Germany
Posts: 3,636
AFAIK there was a solution for AVISynth to undo the distortions of wide angle lenses...
But I don't know its name anymore...

EDIT: http://forum.doom9.org/showthread.ph...rel+distortion

One need to undo the distortion before deshaking.
If the fish-eye look is desired one may re-apply the distortion after deshaking again.
__________________
Don't forget the 'c'!

Don't PM me for technical support, please.
scharfis_brain is offline   Reply With Quote
Old 28th February 2008, 01:18   #84  |  Link
Undead Sega
Registered User
 
Join Date: Oct 2007
Posts: 713
well i remember using 2d3 SteadyMove and i get these weird distortions on my old Hi8 camcorder with just the stock lens with the settings are ranked up high to get the best stablized video.
Undead Sega is offline   Reply With Quote
Old 28th February 2008, 19:08   #85  |  Link
guth
Registered User
 
Join Date: Apr 2003
Location: Uppsala, Sweden
Posts: 152
Actually, this effect doesn't come from the fact that wide angle lenses often are imperfect, but rather from the nature of wide angles.

Most wide angle lenses are usually either rectilinear or fisheye. I guess it's pretty obvious that fisheye lenses will give strange results when deshaking, but the fact is that even perfectly rectilinear lenses will look a bit weird (which that sequence above demonstrates). Here's my attempt at explaining why, in a hopefully easy to understand way...

A rectilinear lens will make straight lines in the world appear straight on the image too. Now, imagine you're taking a close wide-angle picture of a chessboard. All squares will get the same size on the image even though the outer squares are further from the camera than the squares in the middle. This essentially means that objects are magnified when they are close to the edge. When you turn the camera to point at an outer square it will get smaller on the image.

And deshaker doesn't like it when objects change size when you pan the camera...
guth is offline   Reply With Quote
Old 28th February 2008, 21:56   #86  |  Link
Undead Sega
Registered User
 
Join Date: Oct 2007
Posts: 713
Quote:
And deshaker doesn't like it when objects change size when you pan the camera...
i see, is this something you are going to or are wanting to work on?
Undead Sega is offline   Reply With Quote
Old 28th February 2008, 22:44   #87  |  Link
guth
Registered User
 
Join Date: Apr 2003
Location: Uppsala, Sweden
Posts: 152
I have considered it, but to be honest I don't really think it will happen. Not anytime soon anyway. Sorry...
guth is offline   Reply With Quote
Old 28th February 2008, 23:18   #88  |  Link
Undead Sega
Registered User
 
Join Date: Oct 2007
Posts: 713
oh, thats a real shame, it hasnt received an update for a very long time now, i do hope u can get to it one day, i will look forward to it.

and, since speaking to the actual creator of the filter , about the borders, i assume u have watched the video sample from YUVSoft and its comparisions to yours?

can your filter literally recover the missing edges in the black borders?
Undead Sega is offline   Reply With Quote
Old 29th February 2008, 00:58   #89  |  Link
scharfis_brain
brainless
 
scharfis_brain's Avatar
 
Join Date: Mar 2003
Location: Germany
Posts: 3,636
the video of YUVSoft is a LIE!
they didn't set up deshaker properly just to present their own product as the better one.
__________________
Don't forget the 'c'!

Don't PM me for technical support, please.
scharfis_brain is offline   Reply With Quote
Old 29th February 2008, 13:13   #90  |  Link
2Bdecided
Registered User
 
Join Date: Dec 2002
Location: Yorkshire, UK
Posts: 1,673
Deshaker is lovely, but how can I speed it up?

I assumed this would have been asked before, but I can't see a list of which options really speed it up or slow it down in the five pages here.

Cheers,
David.
2Bdecided is offline   Reply With Quote
Old 29th February 2008, 21:46   #91  |  Link
guth
Registered User
 
Join Date: Apr 2003
Location: Uppsala, Sweden
Posts: 152
Quote:
Originally Posted by Undead Sega View Post
i assume u have watched the video sample from YUVSoft and its comparisions to yours?

can your filter literally recover the missing edges in the black borders?
I hadn't watched that video before. How funny.
First they steal the name "deshaker", and now this.

Yes, deshaker can recover missing edges (by taking video data from past and future frames).


Quote:
Originally Posted by 2Bdecided View Post
Deshaker is lovely, but how can I speed it up?
Thanks! I recommend you search for the words "fast" and "slow" here:
http://www.guthspot.se/video/deshaker.htm
guth is offline   Reply With Quote
Old 1st March 2008, 13:40   #92  |  Link
Undead Sega
Registered User
 
Join Date: Oct 2007
Posts: 713
Quote:
Deshaker is lovely, but how can I speed it up?

Thanks! I recommend you search for the words "fast" and "slow" here:
http://www.guthspot.se/video/deshaker.htm
i think this is something new you could work on, meaning adding support for Multithread and MultiCore CPUs? that would be so great if it took advantage of it.

and when it uses previous frames to recover missing edges, does it literally look for wat was suppose to be there?

possible to show an example?
Undead Sega is offline   Reply With Quote
Old 1st March 2008, 13:42   #93  |  Link
scharfis_brain
brainless
 
scharfis_brain's Avatar
 
Join Date: Mar 2003
Location: Germany
Posts: 3,636
Undead Sega: would you PLEASE read the authors site carefully before asking for obvious things?
__________________
Don't forget the 'c'!

Don't PM me for technical support, please.
scharfis_brain is offline   Reply With Quote
Old 1st March 2008, 17:56   #94  |  Link
guth
Registered User
 
Join Date: Apr 2003
Location: Uppsala, Sweden
Posts: 152
I think I'll have to agree with you, scharfis.

It already does multithreading and as for recovering missing edges, please read my site and/or do some testing yourself.
guth is offline   Reply With Quote
Old 3rd March 2008, 14:30   #95  |  Link
2Bdecided
Registered User
 
Join Date: Dec 2002
Location: Yorkshire, UK
Posts: 1,673
Quote:
Originally Posted by guth View Post
Thanks! I recommend you search for the words "fast" and "slow" here:
http://www.guthspot.se/video/deshaker.htm
Thank you.


I have read it (the web page), and used it (deshaker!), but still have a "kind of" question about edges. I'm not sure how to phrase this. Obviously everything in the frame is processed with motion estimation and compensation. However, it seems that the areas out of frame are not. Here's an example of what I'm trying to say...

Let's say the area at the top of the frame is first revealed in original frame 100, but was needed for compensated frames 80-99 too. During those frames, it looks like the static top of frame 100 is copied to the top of frame 80-99. Let's say the existing top of frames 80-99 is moving left to right. It looks like there's no attempt to make the part pasted from frame 100 move left to right - it just sits there.

Now I know you don't actually know how it should be moving, because it's not there in those frames(!) - however, would it not be reasonable to guess that if the parts near it are moving left to right, then the part copied from frame 100 should move left to right too? It might not be spot on, but it might be closer to reality that not moving it. I guess it comes with its own complications...!


Not a criticism (because deshaker is amazing) - just a question/suggestion.

Cheers,
David.

Last edited by 2Bdecided; 3rd March 2008 at 14:32.
2Bdecided is offline   Reply With Quote
Old 3rd March 2008, 15:43   #96  |  Link
scharfis_brain
brainless
 
scharfis_brain's Avatar
 
Join Date: Mar 2003
Location: Germany
Posts: 3,636
deshaker 'only' applies global motion compensation to the frames. This means that only the whole frame is being moved.
This is also done with previous and future frames.
But every movement that does not equal to the whole frames movement - I call it differential movement - will most likely produce some weird artifacts at the compensated borders.
Of course, one could write algorithms that will do local motion compensation on the frames that are being used form border filling. but that would slow down the process even more.
__________________
Don't forget the 'c'!

Don't PM me for technical support, please.
scharfis_brain is offline   Reply With Quote
Old 3rd March 2008, 19:18   #97  |  Link
guth
Registered User
 
Join Date: Apr 2003
Location: Uppsala, Sweden
Posts: 152
Exactly. Thanks scharfis!

This usually means that the background will be moved correctly when taken from another frame, but if there are objects moving in the borders, they tend to look a little weird.

And btw, I have absolutely no problem with questions/suggestions or even criticism. It's actually even slightly ok to ask things that's already on my web page.
guth is offline   Reply With Quote
Old 4th March 2008, 00:51   #98  |  Link
Undead Sega
Registered User
 
Join Date: Oct 2007
Posts: 713
would this be a good example of what your talking about?
Attached Images
 
Undead Sega is offline   Reply With Quote
Old 5th March 2008, 07:58   #99  |  Link
guth
Registered User
 
Join Date: Apr 2003
Location: Uppsala, Sweden
Posts: 152
Quote:
Originally Posted by Undead Sega View Post
would this be a good example of what your talking about?
Yes. But you don't seem to be using "soft borders". You might want to try that.
guth is offline   Reply With Quote
Old 6th March 2008, 13:40   #100  |  Link
Undead Sega
Registered User
 
Join Date: Oct 2007
Posts: 713
also, here is the actual video of using the Deshaker program.

it includes a before and after processing:

http://www.wikiupload.com/download_page.php?id=35945

P.S. i dont know if anyone has seen such shaky camera work either.
Undead Sega is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 09:01.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.