Noise Solution Testing

H

holditnowfilms

Well-known member
I have been trying some experiments on reducing noise on the HVX low light mid low shadows. Here is what I found-

I shot the same scene two ways.
1. I shot the look I wanted using WYSIWYG on the monitor. The shot was low key with 2 sources. A forground element was lit brightly and there were 3 levels of darkness going into the deep background. The noise was horrible even in areas that were not shadow. Only the main key light area was noise free.

2. Same set up only I increased all the lights until it took 4 stops (iris) to make the exposure look the same. Then I backed down 3 stops. At that point the highlights just over exposed and burned out. I recoreded that set up. Next I pulled footage into to FCP and reduced the levels in CC. I easily pulled the detail back into the overexposed hightlights. Then I reduced the mids and blacks until it closely resembled the first shots look. I had to reduce the saturation some also.

I compared the two shots on split screen. Then noise on the first shot was intense. The noise on the second shot was almost gone. There was some noise but it was very small/fine dots and seemed more pleasing to the eye (subjective I know). I did notice some compression artifacts and a little banding in the transistion areas but very slight.

So I was able to get the same** look but the first had mucho noise and the second next to none. It was not all that hard to produce the second look just more powerful lights. I used the iris to check exposure and light range levels quickly. I tried a meter but the iris worked just as good and was more visual and fast.

This may be a hassle for run and gun shooting but if you are doing any kind of lighting it is certainly a viable solution.

I am sure any seasoned DP would know to do this as it's a lot like shooting film but for those of us who have a DVX or video background this is all new. Hope this helps.

**( almost the post fixed shot lost some color in the whites as the CTB gell left a slight blue hue in the whites on the 1st shot but the CC process lost the hue in the 2nd shot. I was using two different temp sources forground and background for effect. My be able to recover blue with CC noodling)
 
Congratulations. Keep up the testing. It makes me glad to see someone actually testing/tweaking rather than just "commenting" on noise.
 
On the first (noisy) shot what camera settings were you using?

I know it appears that gamma curves that crush the blacks are less noisy, but would the news gamma curve hold potential for the overexpose-and-CC-in-post method of reducing noise (in that it holds onto the highlights longer).
 
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Great test. I only did part one. I was also going to try shooting in 1080 this weekend to see if the noise was less in that mode. Did you try that holditnowfilms? Thanks so much!
 
holditnowfilms said:
I have been trying some experiments on reducing noise on the HVX low light mid low shadows. Here is what I found-

I shot the same scene two ways.
1. I shot the look I wanted using WYSIWYG on the monitor. The shot was low key with 2 sources. A forground element was lit brightly and there were 3 levels of darkness going into the deep background. The noise was horrible even in areas that were not shadow. Only the main key light area was noise free.

2. Same set up only I increased all the lights until it took 4 stops (iris) to make the exposure look the same. Then I backed down 3 stops. At that point the highlights just over exposed and burned out. I recoreded that set up. Next I pulled footage into to FCP and reduced the levels in CC. I easily pulled the detail back into the overexposed hightlights. Then I reduced the mids and blacks until it closely resembled the first shots look. I had to reduce the saturation some also.

I compared the two shots on split screen. Then noise on the first shot was intense. The noise on the second shot was almost gone. There was some noise but it was very small/fine dots and seemed more pleasing to the eye (subjective I know). I did notice some compression artifacts and a little banding in the transistion areas but very slight.

So I was able to get the same** look but the first had mucho noise and the second next to none. It was not all that hard to produce the second look just more powerful lights. I used the iris to check exposure and light range levels quickly. I tried a meter but the iris worked just as good and was more visual and fast.

This may be a hassle for run and gun shooting but if you are doing any kind of lighting it is certainly a viable solution.

I am sure any seasoned DP would know to do this as it's a lot like shooting film but for those of us who have a DVX or video background this is all new. Hope this helps.

**( almost the post fixed shot lost some color in the whites as the CTB gell left a slight blue hue in the whites on the 1st shot but the CC process lost the hue in the 2nd shot. I was using two different temp sources forground and background for effect. My be able to recover blue with CC noodling)
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Wpnderful news. Any chance of a split screen jpeg comparison still?
 
Hold it now,
If your ambitious can I suggest a variation for being in a low light situation where you can't fford to light and the choice is to expose properly but risk noise in the dark areas or shoot with gain and print down.
(I have done this in film many times.)

So - Try shooting with Gain up (+6 or even +9) to get the slightly overexposed version which you will "print down" - and compare that to a properly exposed or slightly under version at 0 Db.
 
I used the V-Gamma setting default- I fliped through all the settings. Stretching the blacks really made the noise visible over everything. V-setting they are only in the shadows so I used that setting for the test. Shutter was 60 as the manual said that was the best setting for 24p.

I did mess with the D setting a little. I was able to get it to look like the V stuff but it took more tweaking and a lot more saturation had to be pulled out. I don't think it works well for drama lighting but I think works well for more even lighting situations. I will have to test that more. I could be that all settings will have a use depending on the situation unlike with my DVX which has never been touched since I set it to cine-gamma PA

stabwound- I would put up a Jpeg but it's really hard to tell in a still shot where and how bad the noise is. You really need to see a moving shot. I put the two shots in a loop to make the comparison so they were always moving.


lenileapi- I will give that a try.
 
I'm impressed that you can blow out parts of the image and get the details back in post. Most of the time video is hard to bring back after it is pushed too far. I will have to try this.
 
harlan said:
Congratulations. Keep up the testing. It makes me glad to see someone actually testing/tweaking rather than just "commenting" on noise.
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Now you're completely right.
 
thefilmaddict said:
I will have to try this.
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Jay, since that we are waiting for the european HVX, you are our eyes there.

So we will be waiting for your tests' posts. Thank you!
 
Maybe if we turned down the brightness of the camera monitor, it will make us add more exposure to eliminate the noise.

To me, it seems as though the image is underexposed due to the gama curve the cine settings are putting on the image. The flip out monitor does not acurately show the exposure that the curve is placing on the image. Adding more exposure always helps this camera more than hurts....sort of like film.
 
there is one major issue with this technique - I beleive at above 5.8 the camera chips do not capture full resolution of HD because not enough light is hitting the chip - i have heard this from many sources but of course cannot confirm it myself - the sweet spot is below 5.8
 
Green Hornet said:
Maybe if we turned down the brightness of the camera monitor, it will make us add more exposure to eliminate the noise.

To me, it seems as though the image is underexposed due to the gama curve the cine settings are putting on the image. The flip out monitor does not acurately show the exposure that the curve is placing on the image. Adding more exposure always helps this camera more than hurts....sort of like film.
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I agree with the light: But if the information is in the image there should be a way to get a wysiwyg-like image. I mean: The sensor seems to need a lot of light but there shouldn´t be no need to get the image out of the camera with an overexposed look. Some more digging in the settings might resolve it. That would be very helpful for composing a scene.

To be more expicit: Isn´t there any setting that makes the camera less sensitive so that A LOT of light could hit the sensor - which seems to be important for a noisefree image - and out comes a clear, well lit image?
 
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joe 1008 said:
Isn´t there any setting that makes the camera less sensitive so that A LOT of light could hit the sensor - which seems to be important for a noisefree image - and out comes a clear, well lit image?
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Unlike the Canon H1 (and may full-size cameras) there is no option for a -3dB gain, which would make the image less sensitive but quieter. The only way (it seems) to deal with "lots" of light on the HVX is mechanically with the ND filters.

You have to be careful when overexposing video as there is very little headroom when it comes to highlights. On the plus side, the HVX seems better than most at coping with highlights. Personally, though, it would make me very nervous shooting this way!
 
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