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Pixelated edges


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#1 Shidan Saberi

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Posted 17 December 2010 - 12:05 PM

Hi,

I'm new to this forum. Hello everyone.

I was hoping to get some advice.

I have a Canon hxa1s and i've been getting a problem were the edge of my film and pictures are pixelated. Like stairs. In film it looks like the stairy edges are running around.

I've attached some pictures to demonstrate.

I wanted to know whether this is normal or if there is something i can do to prevent it.

Thank you!

Attached Images

  • problem 2.jpg

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#2 Phil Rhodes

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Posted 17 December 2010 - 12:49 PM

The image you posted is 948 by 531 pixels, which isn't a size produced by any camera system of which I'm aware. You need to post original stills captured directly at full resolution from your camera original files or tapes before any sort of objective assessment can be made.
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#3 Thomas James

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Posted 17 December 2010 - 08:57 PM

You should have bought the progressive scan camcorder.
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#4 Chris Millar

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Posted 17 December 2010 - 09:50 PM

You should have bought the progressive scan camcorder.

It's not interlacing artefacts Thomas.

If it were it'd be on moving objects in frame or on all objects in frame if it were a pan - of which I see neither (I do see some compression though)

The jaggles I think might be the jaggles on the edges of objects in frame (like the cars window frame jaggles where square pixels are trying to emulate an off axis line), as opposed to the edges of the frame - thats just a guess, otherwise as Phil suggests its no use talking about it until we see unaffected and preferably actual motion footage
;)

Edited by Chris Millar, 17 December 2010 - 09:51 PM.

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#5 Chris Millar

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Posted 17 December 2010 - 09:56 PM

UPDATE>>
Oh hang on - pretty sure it is the car window frame he's talking about - he's outlined it with about a 1 pixel sized red line then gone and reduced the image size so most of the line has been sucked up into the rescaling algorithm, then compressed it.

Awesome.

More info please Mr Shiz Miz ... :rolleyes: (careful before the name police turn up)
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#6 Shidan Saberi

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Posted 18 December 2010 - 08:04 AM

UPDATE>>
Oh hang on - pretty sure it is the car window frame he's talking about - he's outlined it with about a 1 pixel sized red line then gone and reduced the image size so most of the line has been sucked up into the rescaling algorithm, then compressed it.

Awesome.

More info please Mr Shiz Miz ... :rolleyes: (careful before the name police turn up)


Thanks for your replies everyone!

My laptop battery was running out so i rushed my explanation.

I outlined the red on the window were it was happening. But the pictures quality got reduced when i put it up here so it got pixelated all over.

I've uploaded them on Flickr for better resolution. It's made it smaller and improved it a bit. Original is worst.

http://www.flickr.co...in/photostream/

(bike fuel tank)

http://www.flickr.co...in/photostream/

(car window frame)

I also realized i made this video when i got the camera.
The piano keys are very pixelated on the edges. (Like at 0.07 seconds into the vid)
It's the same on the camera screen and view finder too when i'm filming or playing it.
It also had a lot of noise which i realized after i had shot it. Turning off gain seemed to fix that. I'm not sure whether that is normal.

Sorry are nickname not allowed on this forum?:)

Edited by Shiz Miz, 18 December 2010 - 08:08 AM.

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#7 Shidan Saberi

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Posted 18 December 2010 - 08:13 AM

The Sheet notes are also pixelated at 1:38

This is the quality footage some people are getting with the same camera



Mine doesn't even come close to it at the moment:(

Edited by Shiz Miz, 18 December 2010 - 08:16 AM.

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#8 Phil Rhodes

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Posted 18 December 2010 - 08:24 AM

We need to see uncompressed (that is, PNG or TIFF) stills of grabs directly from the camera tape in order to see what's really going on. The XH A1 records to HDV, probably at a resolution of 1440x1080 pixels, but your edit software may scale it back up to 1920x1080. If it's smaller than that, you aren't showing us everything, and it's hard to be specific.


That said, from what I can see here, it may just be compression artifacts. HDV is a very heavily compressed format and it will cause artifacts.

What do you like about the material in the Youtube video you posted? Be specific about what you like, and we can probably advise.

And no, nicknames are not allowed here.

P
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#9 Shidan Saberi

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Posted 18 December 2010 - 11:13 AM

We need to see uncompressed (that is, PNG or TIFF) stills of grabs directly from the camera tape in order to see what's really going on. The XH A1 records to HDV, probably at a resolution of 1440x1080 pixels, but your edit software may scale it back up to 1920x1080. If it's smaller than that, you aren't showing us everything, and it's hard to be specific.


That said, from what I can see here, it may just be compression artifacts. HDV is a very heavily compressed format and it will cause artifacts.

What do you like about the material in the Youtube video you posted? Be specific about what you like, and we can probably advise.

And no, nicknames are not allowed here.

P



I have just saved the pictures in PNG. But it's too big to upload here. If i upload it on Flickr will it reduce resolution and be pointless again?

I will check what resolution my camera saves and what my editing program (vagas) changes it to and let you know.

If my editing program doesn't compress the videos a 4 minute video i create will be too big to fit even on a dvd.

What i like about the video i posted is how sharp the images are. Even at at 320p it's very sharp.

How can I change my nickname? I looked around but couldn't change it:S

Thanks!

Edited by Shiz Miz, 18 December 2010 - 11:14 AM.

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#10 Phil Rhodes

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Posted 18 December 2010 - 11:34 AM

Now that I look into it, it is unnecessarily convoluted to change your display name. Here's how.

1) Click on your name next to your post. This will display your profile.
2) Click the "edit my profile" button at the top right
3) Click the "settings" tab at the top left
4) Click "Change display name", fourth button down.

Or you could just have got it right when you signed up - it does say, in very big letters, to use your real name. This is not 4-chan.

Try cropping out (not scaling) a problem area of the image. We don't need to see the whole image, but what we see has to be at full resolution.

Otherwise we could be seeing artifacts related to scaling. I think what you're seeing is just HDV compression artifacts, but I can't be sure.
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#11 Thomas James

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Posted 18 December 2010 - 03:09 PM

You are seeing interlace aliasing artifacts.
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#12 K Borowski

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Posted 18 December 2010 - 04:00 PM

Thomas, it's not cute anymore.


Quit hijacking threads with your 48 fps, progressive crusade.
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#13 Chris Millar

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Posted 18 December 2010 - 04:10 PM

You are seeing interlace aliasing artifacts.


Did you read my reply above ???

We've been down this road before...

Either you are a:

- Troll
- Retard

Non admission to being a troll equates to retard.
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#14 Thomas James

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Posted 18 December 2010 - 05:03 PM

Okay maybe its a deinterlacing artifact caused by a line doubling bob deinterlacer. Unfortuantely most people attribute deinterlacing artifacts only to weave deinterlacers which produce cog like artifacts but there are a lot of other ways to deinterlace.
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#15 Chris Millar

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Posted 18 December 2010 - 08:55 PM

Thomas,

Its not interlacing/deinterlacing artefacts - those come about from motion in the frame...

I don't think there is motion in the frames, either objects or camera movement - take some time to consider this
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#16 Phil Rhodes

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Posted 18 December 2010 - 09:50 PM

Well actually...

The XH A1 does not shoot native progressive scan images - possibly one of the last high-end prosumer cameras (if that makes sense) not to offer that feature. The Canon HDV stuff was and is very sharp, but it really only does interlaced well. Shooting the 24F modes does give you artifacts somewhat like that, from the in-camera deinterlacing, on near-horizontal lines only. Compare with near-vertical lines and things look better. It could just be that, exacerbated by the HDV compression.

P
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#17 Shidan Saberi

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Posted 20 December 2010 - 01:13 AM

Sorry i had to crop it this small to be able to upload it.

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  • IMG_0172 2 crop.png

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#18 Shidan Saberi

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Posted 20 December 2010 - 08:57 AM

I checked and the the camera records in 1920x1080 and the settings on sony vagas is also set to 1920x1080.
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#19 Phil Rhodes

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Posted 20 December 2010 - 09:29 AM

Right, that's how you need to present it.

I strongly suspect that's deinterlacing. Not much you can do about it, other than perhaps shoot it interlaced and use a better deinterlacer in postproduction.

P
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#20 Chris Millar

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Posted 20 December 2010 - 04:33 PM

Aghhh,

Thomas, I stand corrected
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