Thoughts on AF100 - Properly testing for noise

pannyfreak

pannyfreak

Active member
A lot of comments on sample footage seen around the net seem to praise the footage immensely in terms of sharpness, color richness, but one critique crops up repeatedly: Image noise. Particularly in the blacks.

BUT - Are we forgetting nearly all footage on the web from this camera is coming from two websites: Vimeo or YouTube. YouTube, if you right-click on a video during playback and select "Show Video Info" reports 1080p streaming through about 6Mbps peak. And that's using H.264 compression. Vimeo, appears to use around 5Mbps (based on their upload compression recommendation page).

So, could it very well be a lot of the noise in the blacks we're seeing is from watching 24Mbps H.264 recompressed for online distribution into another H.264 6Mbps stream? Shadow detail and dark areas will be the first to be compressed heavily when bitrates lower-- especially when throwing away 75% of the image data!

I propose the definitive test:
When someone gets their AF100 (or even has one now), put the body cap on with no lens. No ND filter engaged. Set ISO to 100, 200, 320, 400, 800, 1600, 3200 and record 5 seconds of each at 1/48 (180 degree shutter). Pull a TIFF from each setting and post as a zip file. Then we'll see inherent noise.


P.S. - Also post the video, something like this: http://vimeo.com/10473734
I haven't seen anyone do anything like this yet with the AF100 and I think would be a great thing to see.
 
pannyfreak said:
A lot of comments on sample footage seen around the net seem to praise the footage immensely in terms of sharpness, color richness, but one critique crops up repeatedly: Image noise. Particularly in the blacks.

BUT - Are we forgetting nearly all footage on the web from this camera is coming from two websites: Vimeo or YouTube. YouTube, if you right-click on a video during playback and select "Show Video Info" reports 1080p streaming through about 6Mbps peak. And that's using H.264 compression. Vimeo, appears to use around 5Mbps (based on their upload compression recommendation page).

So, could it very well be a lot of the noise in the blacks we're seeing is from watching 24Mbps H.264 recompressed for online distribution into another H.264 6Mbps stream? Shadow detail and dark areas will be the first to be compressed heavily when bitrates lower-- especially when throwing away 75% of the image data! .
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You're confusing noise with compression artifacts. Vimeo and Youtube will not add noise. Noise can be added by the camera and certain processes in post production (namely color grading). Don't let anything you've seen thusfar from the AF100 make you think it has too much noise. Everything you've seen so far has been shot with prototypes and pre-production models and no one knew the camera very well yet and/or didn't have much time to shoot with it and get necessarily the best image possible from it. Also, some ISOs will give you more noise than others. For example, with the GH2 (which use a similar sensor as the AF100) typically 400, 800, 1600, 3200 would have less noise than 250, 500, 1250, 2500, even though they are higher ISOs.

Also, there's been very little that's been shot where there's been complaints on comments about too much noise. Most of it has been very clean IMO.
 
Mike@AF said:
You're confusing noise with compression artifacts. Vimeo and Youtube will not add noise. Noise can be added by the camera and certain processes in post production (namely color grading).
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If I have an all black image with a few pixels of noise, and compress it at 10% compression quality or 100% compression quality (i.e. bitrate stream size), the 10% compression will have larger visible artifacts around those single pixels of noise than the 100% compression quality which will replicate the image much more accurately (albeit at higher bitrates). Noise is hard on a compressor and whatever the noise the AF100 may be producing in the blacks may be being accentuated by the lower bitrate compression algorithms of YouTube/Vimeo.

Yes, technically the interference off the imager is called noise, and the interference off the compression algorithm is called artifacts, but lower compression bitrates will make whatever present noise is already in the image a lot worse than higher bitrate compression.
 
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pannyfreak said:
Yes, technically the interference off the imager is called noise, and the interference off the compression algorithm is called artifacts, but lower compression bitrates will make whatever present noise is already in the image a lot worse than higher bitrate compression.
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Well put.
 
I just posted a ProRes file showing the camera going through the ISO progressions at night -- no color correction or grading done, the footage (1080/24 PH) straight from the camera's SDHC card, ingested via Log & Capture, transcoded to ProRes 422, edited, fonted and output in ProRes 422. The file's large at 1.44GB but it might answer some of the questions you have.

Here's the link: http://www.visualedge.tv/blog1/2010/12/thoughts-on-the-panasonic-af-100/

Thanks.
 
Here is something that worried me the other day when I played with a prototype at Cinequipt here in minneapolis, I seemed to see compression artifacts in the blacks on the monitor via HDSDI out. I chalked it up to being hooked up to a bad monitor or it being a prototype. I hope that is the case and it's not normally like that.
 
pannyfreak said:
Yes, technically the interference off the imager is called noise, and the interference off the compression algorithm is called artifacts, but lower compression bitrates will make whatever present noise is already in the image a lot worse than higher bitrate compression.
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The compression will make anything look worse, even very low-noise footage. To say compression makes noise look worse of course is true, but it's not just noise. If you want to solve any noise problems it has to start with the camera and the color grading. Camera noise and compression artifacts are not the same. They look different.
 
Yes, technically the interference off the imager is called noise, and the interference off the compression algorithm is called artifacts, but lower compression bitrates will make whatever present noise is already in the image a lot worse than higher bitrate compression.
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Calling compression artefacts "noise" seems to be a tendency of Japanese -> English translations, I've found.

Actually, aggressive compression can actually have a noise reduction-esque effect. Of course, they're both nasties we don't want in the picture, and the two don't play nicely together!
 
Lyris said:
Calling compression artefacts "noise" seems to be a tendency of Japanese -> English translations, I've found.

Actually, aggressive compression can actually have a noise reduction-esque effect. Of course, they're both nasties we don't want in the picture, and the two don't play nicely together!
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so true! i shot a very noisy low light high ISO nightsky with my gh1. it had a lot of NOISE but when uploaded to youtube the COMPRESSION cleared out that sky and made it seem even and noiseless LOL. long live compression!
 
All this and that about noise!!! Name a few cameras that have better noise than what we think the AF100 will have?????
 
If you think the noise on the AF100 will be a hinderence to you making an award winning tvcm / music vid / documentary / narrative - better get yourself an Alexa or Epic. Ive said it before and Ill say it again - on my Pana pro plasma / CRT via HD-SDI or for that matter my 30" apple display thats RGB calibrated, Im just not seeing anything excessive. Nothing that remotely worries me anyway.

Now Im sure when everyone has one, some people are going to be able to produce some noisy footage. What those people then need to understand is how to avoid noise in a digital medium and specifically to a lesser extent what they did on the AF100 to cause it. Then we'll be in a position to help.

For me the AF100 has turned out to be more than I expected. I hate dissapointment, so I dont usually get too excited until Ive used. Ive done that.
 
noel evans do me a favor please view leo ticheli's 5d vs. red one vs. af100 comparison video he recently posted and when the shot goes to the woman in a black dress, check out her back side in the shadows. i'm seeing abominable noise the likes of which i have never seen in my life on any camera. what are you seeing on your uber setup?
 
To appease you I looked again. I see what youre talking about. And? Check out the armpits on the girl from the red shot - this is highly compressed. Not sure what you want.

Ive got a load of files I shot here on the AF100 - the original AVCHD from the camera - and Im not seeing it there. One very similar in shade to this.
 
Noise! Noise! Noise!

grinchnoisenoisenoise.jpg
 
Homunculus said:
noel evans do me a favor please view leo ticheli's 5d vs. red one vs. af100 comparison video he recently posted and when the shot goes to the woman in a black dress, check out her back side in the shadows. i'm seeing abominable noise the likes of which i have never seen in my life on any camera. what are you seeing on your uber setup?
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The subject of the noise on that particular shoot was beaten to death a couple weeks ago. A lot of people think it was something wrong with the pre-production model of the camera or black balance or post workflow, and others think it's strictly an issue with computer monitor and television calibration. At this point I say it's an anomaly because there's plenty of footage out there with no noise. I don't think noise will be an issue with the camera at all. Stick to 200, 400, 800, 1600, and 3200 ISO and you'll probably get less noise than other ISOs, but we'll see when the ISO tests start popping up from production models.
 
FWIW, I had about a half hour with a prototype a couple of months ago at DV Expo in Colorado. With the Oly lens it looked great, but since I was planning on getting the Lumix, I had the rep put that lens on. To get something close to the look of the Oly lens we had to crank the gain.

It looked really good. I'm not recommending that method of course (in fact, for those of us that actually light shots as opposed to ENG work, I've never understood why low-light is such a deal breaker for so many people...sure I'd prefer more light sensitivity, but I can usually control how much light I'm using), but, although there was some noise, it was far, FAR cleaner than I expected. So I'm guessing (as unscientifically as I can), that if I actually properly expose my shot for the sensitivity of the camera combined with the lens I am using, it should look pretty kick-ass. It can't be noisier than my HVX, and I've seen some pretty darn good footage out of that camera.

But, I tend to shoot more than I think.....
 
dustylense said:
All this and that about noise!!! Name a few cameras that have better noise than what we think the AF100 will have?????
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Sony EX-1.

Sorry, we all know Panasonic cameras for some time, and yes they are noisier. Sure, we can get over it: we get more noise for a better colorimetry, but there's no point in denying.
 
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