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Sony HVR-Z1 / HDR-FX1
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Old December 22nd, 2005, 08:29 AM   #1
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color gradation artifact?

Hi all,

I got my FX1E back in mid-Nov, but haven't shot much (yet).

From some of the footage, I noticed some steps/blocks in the background (around the mic):

http://fa-studio.org/video/screenshot8.jpeg

Is it normal - HDV just can't cope with these "flat color with continuous brightness gradation"? Then I have to learn how to avoid it in future.
Or abnormal - I have to send it in for repair?

Merry Christmas,
James Wong H.W.

p.s. I am not a native english speaker, so please forgive my weak written english.
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Old December 22nd, 2005, 08:52 AM   #2
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Quote:
Originally Posted by James Wong H.W.
Hi all,

I got my FX1E back in mid-Nov, but haven't shot much (yet).

From some of the footage, I noticed some steps/blocks in the background (around the mic):

http://fa-studio.org/video/screenshot8.jpeg

Is it normal - HDV just can't cope with these "flat color with continuous brightness gradation"? Then I have to learn how to avoid it in future.
Or abnormal - I have to send it in for repair?

Merry Christmas,
James Wong H.W.

p.s. I am not a native english speaker, so please forgive my weak written english.
I can't see any on my LCD 768 dpi. What are you using to monitor?
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Old December 22nd, 2005, 09:18 AM   #3
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Yes, that's totally normal for HDV. And yes, it can't cope with "flat color with continuous brightness gradation". Most 8bit cameras will have problems with that, and the strength of HDV compression just makes it all the more obvious.

Graeme
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Old December 22nd, 2005, 09:27 AM   #4
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Hmm... I don't have HD monitor; just what i saw when playing back the capture files in QT on my cheapo DELL 20".

I have highlighted that part:
http://fa-studio.org/video/screenshot8m.jpg

Any clue?
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Old December 22nd, 2005, 09:35 AM   #5
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Quote:
Originally Posted by Graeme Nattress
Yes, that's totally normal for HDV. And yes, it can't cope with "flat color with continuous brightness gradation". Most 8bit cameras will have problems with that, and the strength of HDV compression just makes it all the more obvious.
O... really?
I haven't found any serious artifacts from HDV footage with detailed background/relatively fast camera movement yet (which most ppl think HDV is weak at), BUT instead have problems with plain simple background... :(

Is that odd? :P
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Old December 22nd, 2005, 11:40 AM   #6
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No, it's normal. The only video problem I have with my Z1 is banding on flat-colored walls and the like, particularly if I push color grading too far... otherwise it's pretty much artifact-free.
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Old December 22nd, 2005, 01:24 PM   #7
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I've seen these artifacts on pretty much all the HDV footage I've got. I also see it on Varicam footage, but not as bad, but it's there, especially when you begin to colour correct.

Graeme
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Old December 22nd, 2005, 04:28 PM   #8
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Welcome to to DVinfo James. Let me assure you that your English is excellent and not at all weak!

I see the blocks you're talking about, although they're pretty subtle. I have to agree with Graeme (as usual :-) - this looks pretty much the same as what I frequently see in standard definition DV. It's easy to make this sort of thing worse if you do any major color correction. 8 bits just isn't enough to provide nice gradients. It's a constant source of frustration for me as well, but you just have to expose for the most important part of a scene, which you've done with the singer.
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Old December 22nd, 2005, 04:33 PM   #9
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8 bit is enough if the data is dithered, but....

High compression removes dither and natural noise that breaks up the appearance of banding,

hence,

this artifact is worse in high compression codecs such as HDV, not quite as bad with DVCproHD, not too bad at all with DV, almost never seen in noisey old analogue formats like BetaSP. Yes, noise can be good!

Graeme
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Old December 22nd, 2005, 05:30 PM   #10
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Quote:
Originally Posted by Graeme Nattress
8 bit is enough if the data is dithered, but....
True; for example, if you set your Mac monitor for 8-bit color it will dither the images, which helps a lot. Of course you can see dots if you look closely however.
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Old December 22nd, 2005, 10:20 PM   #11
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Thanks very much for all your replies~

Then I have to frame my object carefully & find a proper background, to avoid these in future.

THX and MERRY CHRISTMAS! ^.^
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