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Is there any noise or not?


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#1 Mate Marich

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Posted 08 November 2010 - 05:52 PM

I have a shot footage at ISO 100(T2i), and when I first saw it on my laptop, I noticed significant noise on actors black jacket. You can watch one bad take at -->

But today I bought a mini-hdmi cable, and when I was testing this video on tv, the noise was gone.

Now, I have a lot of questions, so if you could please help me:
Is there any noise, and where is it coming from (ISO 100)? Who do I trust, laptop or TV?
What is the maximum that can be drawn from these footage?
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#2 Saul Rodgar

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Posted 08 November 2010 - 10:22 PM

I'm afraid is next to impossible to accurately judge original-source grain from a youtube video. What you posted seems pretty clean to me tho. You are not giving enough information about your post processing. If you saw grain on your laptop, could any transcoding or wrong setting on your editing software be causing this? I would think that is something to look into, since you mention that the HDMI signal from the camera straight to the HDTV monitor was clean.

Without having more info, and maybe even after having more info, I'd trust the clean signal on the HDTV more than what you are seeing on the laptop. I'd be inclined to think that something is happening to the footage in digital post that is causing it to look grainy.
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#3 K Borowski

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Posted 08 November 2010 - 11:02 PM

Looked perfectly clean to my eyes as well. I have a crap, uncalibrated LCD monitor set to 5000K, that may or may not be at the right angle.



If you are color timing yourself, I would highly recommend you get a professional monitor, or at least get *access* to one. Have any friends in with connections? I'm sure laptop LCDs have gotten a lot better, but you have to make sure you have one designed for professional graphics use and you have it calibrated.

I think CRTs are still the best for this sort of work, if you can find them.
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#4 Mate Marich

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Posted 09 November 2010 - 08:24 AM

Here's more information: the footage isn't processed, compression is h.264 1920x1080 24p

After I watched the footage footage on more than one monitor and saw that sometimes there's noise, and sometimes there isn't any. That's good and bad news at the same time. The good news is the footage is noise free, and the bad news is I don't have a compatible monitor to work on.

Do you have any advice about processing the footage in order to make it noise free on most monitors? Do I have to compromise, and how much?
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#5 Hal Smith

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Posted 09 November 2010 - 09:02 AM

Was the "Highlight Priority Tones" (HTP) preset on? The high-end professionals using the Canon HDSLR's have figured out that HTP protects highlights pretty much ignoring any effect on the blacks. As a result the blacks can get noisy because the camera was actively keeping highlights from burning out. Since HTP is an automatic computer function inside the camera you have no control over this behavior. The obvious fix is don't use HTP unless you're shooting under uncontrolled lighting situations like a live stage show with very bright light sources like followspots in use.

There really aren't any good cheap monitor options. The only "bargain" I know of is if you need to buy a high end laptop buy one of the HP Elitebooks that are available with DreamColor LCD displays. It adds $400 to the purchase price of the laptop but gives you the full equivalent of a $2400 DreamColor monitor.

Edited by Hal Smith, 09 November 2010 - 09:06 AM.

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#6 Phil Rhodes

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Posted 09 November 2010 - 06:15 PM

I find HTP to be pretty reliable, and generally run with it on. Unless I've missed a critical piece of information, it programatically underexposes by one stop, by reducing the effective ISO (which is why ISO100 becomes unavailable), then curves it back up. This wouldn't seem to be anything you couldn't do by underexposing and putting a curve into the image style, but as far as I know it is a consistent and linear effect.
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#7 Tim Tyler

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Posted 20 December 2010 - 08:26 PM

I shot some 1080/29.97 clips with my 7D and the lens port cover on. I just wanted to see how the blacks would be affected with noise based on ISO and Highlight Tone Priority variables. (Visible noise in these examples has been uniformly exaggerated.*)

Neutral Preset with:
0 Sharpness
-4 Contrast
-2 Saturation
0 Color Tone

STD.png

With HTP turned off, the ISO with the least video noise was either ISO 100 or 250. They were both about the same.
Next best was ISO 160, followed by 125, 200 and 320 which all looked about the same.

HTP.png

With HTP enabled, 320 was the least noisy. The remaining ISO's all exhibited similar noise characteristics, but 400 and 500 seemed slightly less noisy than 200 and 250.

Attached File  7d-iso-test.zip   46.15KB   27 downloads (Open these PNG's in Photoshop and zoom in to see the detail.)

*Clip processing:
  • MOV's importeded in Premiere CS5
  • 1080 frame grabs exported as TIFF's to Photoshop
  • Photoshop: Midtone Level Adjustment = 3

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