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Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


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Old March 26th, 2011, 05:26 PM   #1
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The color black and the XHA1

I noticed that sometimes the color black pixalates quite a bit even under good lighting conditions. I'm starting to wonder if this has more to do with the camera itself. Any thoughts?
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Old March 26th, 2011, 11:17 PM   #2
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Re: The color black and the XHA1

Do you have a custom setting running that might affect the blacks?
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Old March 26th, 2011, 11:40 PM   #3
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Re: The color black and the XHA1

Not using any custom presets. It doesnt always happen, however its happened when shooting both 60I and 30p. When the final product is burned to dvd the noise/pixalation usually disappears.
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Old March 27th, 2011, 01:06 AM   #4
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Re: The color black and the XHA1

The gamma setting seems quite high in default but you are probably loosing it by the time it get encoded for dvd. I personally like seeing some detail in the dark areas. Unlike Sony cameras that seem to give you a brilliant hi contrast right out of the box. Cannon allows you to customize it in post to get that sony zing.
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Old March 27th, 2011, 11:39 AM   #5
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Re: The color black and the XHA1

Kevin:

Yes, it does have to do with the camera and also with HD video.

The basic problem is (in the grossly oversimplified terms I understand) that HD video has a great many small pixels and having lots of small pixels for HD has made many HD cameras susceptible to video noise in the dark/black areas. When you make a DVD, you are down-rezzing to SD --- fewer and larger pixels --- which makes the noise/grain much less apparent.

There are numbers of settings (including some of the downloadable presets) which help limit the problem for when you want to view your footage in HD. I found, unfortunately, there is no simple "one size fits all" solution that automatically works for everybody. I found I had to try try several approaches and mixes of them to find the ones that worked best for my shooting conditions.

Video noise is variously referred to as twitter, grain, pixellation and noise. Search on those terms in this forum and you will find numbers of threads with suggestions for settings you can try.
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Old March 27th, 2011, 12:03 PM   #6
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Re: The color black and the XHA1

Kevin:

Yes, it does have to do with the camera and also with HD video.

The basic problem is (in the grossly oversimplified terms I understand) that HD video has a great many small pixels and having lots of small pixels for HD has made many HD cameras susceptible to video noise in the dark/black areas. When you make a DVD, you are down-rezzing to SD --- fewer and larger pixels --- which makes the noise/grain much less apparent.

There are numbers of settings (including some of the downloadable presets) which help limit the problem for when you want to view your footage in HD. I found, unfortunately, there is no simple "one size fits all" solution that automatically works for everybody. I found I had to try try several approaches and mixes of them to find the ones that worked best for my shooting conditions.

Video noise is variously referred to as twitter, grain, pixellation and noise. Search on those terms in this forum and you will find numbers of threads with suggestions for settings you can try.
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Old April 4th, 2011, 07:44 PM   #7
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Re: The color black and the XHA1

Can anyone reccomend a custom preset that can help avoid grain/noise in the color black? I am fairly satisfied with the out of the box settings but I really need to come up with a soultion for noisy dark colors. In the past most of my delivery has been on dvd which pretty much elimnates the problem. There is a big difference when rendering to a file.
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Old April 5th, 2011, 09:18 AM   #8
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Re: The color black and the XHA1

In my continued attempt at resolving the noise issue I have spent quite a bit of time reading over some of the older threads about presets. Can someone tell me what the differences are between the following:

Pressing the blacks, Stretching the blacks and Middle.

Thanks.
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Old April 5th, 2011, 10:58 AM   #9
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Re: The color black and the XHA1

What's your gain set on? In general, the lower the gain, the less grain you will see in your images. Grain is usually easier to see in the dark colors.

Sometimes the gain setting is higher on my camera than I think it is. Usually it's leftover from a previous shoot in low light that I don't always notice right away due to fatigue, lack of coffee etc.
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Old April 5th, 2011, 12:17 PM   #10
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Re: The color black and the XHA1

The gain is set to zero. Perhaps I should set it to -3? Keep in mind that I am shooting under controlled lighting conditions.
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Old April 6th, 2011, 10:23 AM   #11
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Re: The color black and the XHA1

Well, it's not the gain setting then. I usually do -3, but sometimes 0, and even up to +6. How long have you had the camera? Is this a problem that just started recently?

You said the phenomenon usually disappears on the finished DVD. Are you also seeing the effect in the preview screen/window of your NLE? Try to note when the phenomenon appears and when it doesn't.

Could it possibly be the display device, tv or monitor you're watching the footage on, or cable to the device? Does the phenomenon occur when playing back a tape from the camera connected to the display device? Does it occur with live output to a display device?

I bought my A1 used about 16 months ago, and have used it on more than 50 gigs since the purchase. What you are describing isn't normal behavior for an A1, at least in my experience. Maybe something is out of whack somewhere in the customized settings starting on page 83 of the manual.
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Old April 6th, 2011, 01:13 PM   #12
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Re: The color black and the XHA1

Roger I have had my A1 for over 2 years and its been great. In the past, mosy of my projects have been rendered to a DVD. Recently I have been rendering to files which is when the problem occurs. I am starting to think that it may be the way my nle is handling the footage. I am curently using Pinnacle Studio 12. I was experimenting with Sony Vegas last night and I seem to be getting a much better result. I need to experiment more but perhaps all MPEG2 and MPEG 4 files are not created equal. It seems the ones created from Vegas are yielding a better result?
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Old April 7th, 2011, 05:24 PM   #13
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Re: The color black and the XHA1

Maybe a colorspace issue is also involved. The 601 colorspace used for television is different than the RGB color space used for computer graphics, especially when dealing with blacks. Color range is 0-255 for RGB but less for 601 colorspace.

The XHA1 shoots in the 601 colorspace. If the mpeg files are being rendered to RGB colorspace, what's black in the 601 colorspace turns out in shades of grey in RGB color space.

If there are grey blocks and stray pixels showing up in the black areas, maybe that's the culprit.

There are some long threads on the AVID forums discussing color space differences and which color space to choose when rendering. I don't think Studio 12 lets you choose, but I haven't looked. I rarely use Studio 12. Don't know about Vegas.
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Old April 10th, 2011, 03:45 PM   #14
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Re: The color black and the XHA1

Is it possible that the shutter speed is the culprit? Recenlty I have been shooting 30f with a shutter speed of 30. Yesterday I shot 30f with a shutter speed of 60 and it seems that the noise in the blacks is no where near as bad as before. Could the 30 shutter speed be the blame?
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Old April 10th, 2011, 07:43 PM   #15
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Re: The color black and the XHA1

Quote:
Originally Posted by Kevin Lewis View Post
In my continued attempt at resolving the noise issue I have spent quite a bit of time reading over some of the older threads about presets. Can someone tell me what the differences are between the following:

Pressing the blacks, Stretching the blacks and Middle.

Thanks.
Kevin

Pressing the blacks means that the black on a subject will be a very dark black, which means any distinguishing features in the 'black' area will be supressed and will not be perceptible. Stretching the blacks is like the opposite of Pressing the blacks.

Regards
Shelton.
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