Black Stretch/Press in Final Cut HD at DVinfo.net

Javier Urena · August 19th, 2005, 05:34 PM

I recently shot some footage with my camera settings set to "Stretch" the blacks. This means it lightens the black areas of the picture to capture more detail. After seeing the footage I now regret the decision to shoot this way because it's giving me a very "video" look instead the film look I was after. The footage is noisy to begin with because I shot in low light and had to bump up the gain on an XL2. Stretching the blacks, rather than pressing them, is making the noise more visible.

So, my question is, how do we press (or compress) the blacks in Final Cut HD? And is it a good idea to do this in post or should I have done it when shooting?

TIA

Zach Mull · August 19th, 2005, 06:18 PM

Javier,
You'll want to use the 3-way Color Corrector filter and the waveform monitor in Final Cut. Apply the filter, adjust the blacks with the left slider until you are happy and check the levels on the waveform (blacks should be at 0% if you want them to be true black). The 3-way Color Corrector should not add noise (it's theoretically YCbCr native), and if you are crushing blacks, it may reduce some noise (remapping all these pixels to black). Make sure you use the "paste attributes" command for similar clips so you don't have to adjust every one.

Some DPs shoot with blacks high knowing someone will crush them in post later. The idea, like you said, is to make sure the detail is there. It's an OK practice, but if you can manage to shoot correct blacks while shooting that's always more efficient, and costs you less if you have to pay an editor/colorist.

Glenn Chan · August 19th, 2005, 10:51 PM

1- Anyone try Nattress' DVNR from his filter set 1?

http://www.nattress.com/set1.htm

There's a functional demo.

2- The 3-way CC does not add noise, but can make it more visible. When you "stretch" colors (i.e. make blacks blacker, or make whites brighter; stretch is my term... nothing to do with XL2 settings) it will make noise more visible.

Try dropping the gamma.

3- If you have Nattress' film effects, black diffusion may also work well?

Javier Urena · August 21st, 2005, 01:40 PM

Thank you Zach, we're going to try this after we've made a rough cut.

Quote:

The 3-way CC does not add noise, but can make it more visible. When you "stretch" colors (i.e. make blacks blacker, or make whites brighter; stretch is my term... nothing to do with XL2 settings) it will make noise more visible.

Glenn, Are you sure about this? The footage is noisy already and the last thing I want to do is add more noise. I would guess that crushing the blacks would make noise less visible in those areas.

The whites were shot with a low knee setting which helps to keep them from blowing out. I don't need to adjust them but I can see how brightening them would add noise.

Graeme Nattress · August 21st, 2005, 04:16 PM

Try the G S-Gamma filters in Film Effects. They do wonderfully nice crushing of blacks. Also, play with the curves control, and adding diffusion can disuise noise quite nicely.

Graeme

Glenn Chan · August 21st, 2005, 07:39 PM

Quote:

The footage is noisy already and the last thing I want to do is add more noise. I would guess that crushing the blacks would make noise less visible in those areas.

Curshing the blacks would make noise less visible in those areas. It will make the noise in the bright parts of the image more visible, although that noise is pretty neglible. So crushing/clipping the blacks may not be a big deal. FCP's 3-way CC will clip blacks, while Nattress' filters with the S gamma will crush it (looks better).

2- Another option:
Create a new sequence.
Drag your edited sequence in there (nesting).
Do it again onto another track.
On the upper track, set the compositing mode to overlay or hard light. This gives results like S-shaped gamma curves.
Apply gaussian blur to the upper track. This does diffusion.

This affects the realism of your footage, but artistically you may find it looks good.

Just giving you differerent options here... there's many different ways to do this. Graeme Nattress has watermarked and fully-functional demos for his excellent filters, which you can play around with. Film effects is very useful for making your images look better.

Javier Urena · August 21st, 2005, 10:24 PM

I do not have any money to buy a plug-in. As for adding diffusion, I shot with a Black Pro Mist 1/2 filter on the lens. I don't want to soften the image anymore than I already have.

I'm going to do what Zach Mull suggested and I'll post later about the results.

Zach Mull · August 21st, 2005, 11:05 PM

Glenn,
What is the difference between clipping and crushing blacks? I've never heard this distinction before.

Javier Urena · September 1st, 2005, 06:24 PM

We used Zach's method and everything looks great. The only thing we did differently was to adjust the blacks by using numbers rather than the slider. For example, each shot was adjusted to -8, -15, -22, etc... The process was very quick once we figured out what we were doing, and the resulting image quality is 100% better. Noise decreased immensely. It had the side effect of enhancing some of the colors as well.

After this experience, I'm convinced the proper method is to shoot with the blacks stretched and then crush them in post. If I had crushed them in camera, we would not have had as much control during editing.

Glenn Chan · September 1st, 2005, 06:39 PM

Quote:

What is the difference between clipping and crushing blacks?

Sorry, I wasn't being very clear there. Usually I use the terms clipping and crushing to mean exactly the same thing.

What FCP's 3-way CC does: Clips blacks.

What Nattress' filters can do: They can emulate film's gamma response (not sure if that's the correct term), which does an s-shaped gamma curve. In the shadow areas, it kind of compresses them without clipping (like how there's smooth knees for audio compressors to prevent clipping).

August 19th, 2005, 05:34 PM	#1
Javier Urena Regular Crew Join Date: Aug 2005 Location: Los Angeles Posts: 67	Black Stretch/Press in Final Cut HD I recently shot some footage with my camera settings set to "Stretch" the blacks. This means it lightens the black areas of the picture to capture more detail. After seeing the footage I now regret the decision to shoot this way because it's giving me a very "video" look instead the film look I was after. The footage is noisy to begin with because I shot in low light and had to bump up the gain on an XL2. Stretching the blacks, rather than pressing them, is making the noise more visible. So, my question is, how do we press (or compress) the blacks in Final Cut HD? And is it a good idea to do this in post or should I have done it when shooting? TIA

August 21st, 2005, 04:16 PM	#5
Graeme Nattress RED Problem Solver Join Date: Sep 2003 Location: Ottawa, Canada Posts: 1,365	Try the G S-Gamma filters in Film Effects. They do wonderfully nice crushing of blacks. Also, play with the curves control, and adding diffusion can disuise noise quite nicely. Graeme __________________ www.nattress.com - filters for FCP

August 21st, 2005, 10:24 PM	#7
Javier Urena Regular Crew Join Date: Aug 2005 Location: Los Angeles Posts: 67	Thank you for your advice I do not have any money to buy a plug-in. As for adding diffusion, I shot with a Black Pro Mist 1/2 filter on the lens. I don't want to soften the image anymore than I already have. I'm going to do what Zach Mull suggested and I'll post later about the results.

September 1st, 2005, 06:24 PM	#9
Javier Urena Regular Crew Join Date: Aug 2005 Location: Los Angeles Posts: 67	Thank you. We used Zach's method and everything looks great. The only thing we did differently was to adjust the blacks by using numbers rather than the slider. For example, each shot was adjusted to -8, -15, -22, etc... The process was very quick once we figured out what we were doing, and the resulting image quality is 100% better. Noise decreased immensely. It had the side effect of enhancing some of the colors as well. After this experience, I'm convinced the proper method is to shoot with the blacks stretched and then crush them in post. If I had crushed them in camera, we would not have had as much control during editing.

August 19th, 2005, 06:18 PM	#2
Zach Mull Major Player Join Date: Feb 2005 Location: Portland, OR Posts: 273	Javier, You'll want to use the 3-way Color Corrector filter and the waveform monitor in Final Cut. Apply the filter, adjust the blacks with the left slider until you are happy and check the levels on the waveform (blacks should be at 0% if you want them to be true black). The 3-way Color Corrector should not add noise (it's theoretically YCbCr native), and if you are crushing blacks, it may reduce some noise (remapping all these pixels to black). Make sure you use the "paste attributes" command for similar clips so you don't have to adjust every one. Some DPs shoot with blacks high knowing someone will crush them in post later. The idea, like you said, is to make sure the detail is there. It's an OK practice, but if you can manage to shoot correct blacks while shooting that's always more efficient, and costs you less if you have to pay an editor/colorist.

August 19th, 2005, 10:51 PM	#3
Glenn Chan Inner Circle Join Date: Jun 2003 Location: Toronto, Canada Posts: 4,750	1- Anyone try Nattress' DVNR from his filter set 1? http://www.nattress.com/set1.htm There's a functional demo. 2- The 3-way CC does not add noise, but can make it more visible. When you "stretch" colors (i.e. make blacks blacker, or make whites brighter; stretch is my term... nothing to do with XL2 settings) it will make noise more visible. Try dropping the gamma. 3- If you have Nattress' film effects, black diffusion may also work well?

August 21st, 2005, 11:05 PM	#8
Zach Mull Major Player Join Date: Feb 2005 Location: Portland, OR Posts: 273	Glenn, What is the difference between clipping and crushing blacks? I've never heard this distinction before.