Master Ped

[Dustin Wadsworth]

So I was reading some comments on Jarred's visual explaination of master ped and I noticed that some people crush the blacks in camera via master ped and some people do it in post.

I just started experimenting with the color correction tool in Vegas and I've been lowering the gamma and offset a tad and raising the gain to get the blacks where I want them. I don't have a very good understanding of what exactly gamma and offset really do so I've been just playing it by eye.

Is this the way that most people crush their blacks in Vegas or is there a better way?

[HorseFilms]

You can also use the Color Curves plugin. I like that a lot. You can really crush your blacks and boost your contrast a lot by applying an "S" curve similar to this:
http://www.horsefilms.com/images/curve.jpg

I just apply that curve by eye, so for each lighting situation, it's slightly different.

[Brandon Rice]

I do the same sort of thing in Avid with the color curves.

[kplo]

I use the level control in Vegas to do this, while viewing the waveform display.
Similar to curves, but a bit more intuitive for me.
The technique (I think Spot suggested this a while back) of applying the black & white filter to a scene makes it easier to get the levels/contrast right. Particularly helpful with low contrst/underexposed scenes. Then, disable that filter and adjust for color.
Hope this helps.
Ken
the Screen Skins guy

[epicedium]

You should definitely learn to use colour curves! Levels are fine for some basic operations (changing black/white points and gamma), but colour curves are far more powerful. Regarding gamma, you should really read up on what gamma correction is for, and understand the transform to and from linear space (ie. 0.4545<->2.2 gamma) ... Sometimes you really do just want to use Levels to alter the blackpoint or raise the gamma for web-distribution.... but if you're grading your film and working for aesthetic reasons, then you really need to be using your curves.

[kplo]

Epicedium,
Having been a Cinematographer for 40 years, I suspect that a little knowledge about gamma has managed to seep into my old brain. The white-black-gamma controls in Vegas' levels panel overlap and affect each other when you adjust them.
My work is primarily commercials for broadcast, so I pretty much know where my roll off points on the curve are because I light for them, but in the run and gun or verite/documentary world, every scene can have a completely different tonality/range, making it a daunting task for a beginner to simply match and lock the ped with curves.
The first poster's question was about crushing the blacks in camera or post.
I believe in his case, that a simple numerical adjustment in the levels panel for black level and a tweak for gamma (there are no numerical controls in the curves panel) will give him simple, repeatable results to lock his black level and get a good headstart on the process.
Hope this helps.
Ken
the Screen Skins guy

[Dustin Wadsworth]

Awesome guys thanks. Yeah it looks like I'll be doing some research on gamma today.

[David Jimerson]

I'd note that you can have repeatability simply by saving your preset.

[epicedium]

Ken- I can't disagree with anything you say! But please note that the original poster seemed interested in getting into colour correction- if he is looking to crush his blacks (an aesthetic step) then he should know that "curves" can offer more precise control over the delicate crushing process (even if it is more complicated).

Indeed, he should probably thoroughly get used to Levels, rather than skip it and go straight into colour curves ;)

Final point-- tweaking the curves while looking at your waveform and/or histogram will give you very good repeatability and tonal control. This is essentially how my own projects are graded-- I curve every individual clip and get a feel for the waveform/histogram character of the clips. Some will need saturation adjustment, if they're being pushed up and down. Once all clips are spot on and consistant, I'll do my global grading on top....

[Dustin Wadsworth]

I'd note that you can have repeatability simply by saving your preset.

This is something I quickly picked up on!


tweaking the curves while looking at your waveform and/or histogram will give you very good repeatability and tonal control.

I have a general understanding of how the historagram works so I'll be playing with that today as well as levels and curves.


Once all clips are spot on and consistant, I'll do my global grading on top

What's global grading? Do you mean that after you get all your clips (individually) consistent that you then start applying changes with the track fx?

Another question: There is Sony Color Corrector and Sony Color Corrector (secondary.) Do you guys usually use one or the other or are these meant to work together? (i.e. the cc is applied and then the secondary is used more for the finishing touches.)

[epicedium]

What's global grading? Do you mean that after you get all your clips (individually) consistent that you then start applying changes with the track fx?

Exactly- your clips should be made consistent first, including colour saturation- important to correct that if you're matching them with curves or levels. Once they're consistant, you can do track or global level effects.


Another question: There is Sony Color Corrector and Sony Color Corrector (secondary.) Do you guys usually use one or the other or are these meant to work together? (i.e. the cc is applied and then the secondary is used more for the finishing touches.)

Oh, they're for completely different things. I've never used "colour corrector" (although that's not to say people don't get good results with it, maybe they do?), but I use secondary corrector all the time. Simply put- colour corrector affects everything, secondary colour corrector only affects masked regions of your image... You eye-drop a colour and set hue/say/lum tollerances- this creates a "mask" for the colour corrector. I tend to use them for fixing- say if your person's face is too red/pink, you can set up a secondary which targets saturated red tones ... and simple does a sat -30%, for example.

[glenn chan]

The master pedestal in the camera will usually apply an 'offset' to all the values... which is the same as saying you add or subtract a certain amount from all values.

In Vegas, the easiest way to do this would be to use the levels filter, and adjust input start.

The Curves filter can also do the same thing... everything the levels filter does, the curves filter can do too. The interfaces are different though, so certain things are difficult/tedious to do in curves.
*The levels filter has some bugs in its implementation, so it doesn't round numbers and it can clip values when "output start" is used.

2- When you're working with video sources (not computer-generated sources), Vegas usually works in Studio RGB color space. Black is at 16 16 16 RGB, and white is at 235 235 235 RGB. When you burn a DVD, anything outside that range is prone to clipping.

So you might want to use the following color curves presets, which has a pair of points at 16 and at 235.

http://www.glennchan.info/Proofs/forums/sony/curves-and-secondary-presets.veg
http://www.glennchan.info/Proofs/dvinfo/color-curves.veg

You can drag-select a pair, and use the arrow keys to move them. This will allow you to adjust master pedestal for example. However, the curve will no longer be straight in the middle... so you ahve to manually straighten it out. So levels may be more convenient here.

3- You can make the middle part of the curve s-shaped like horsefilms pointed out. The concave up part at the bottom will crush the blacks a little.

4- The color corrector operates in Y'CbCr color space... IMO, this is not a good color space to do color corrections in unless you want something that emulates a proc amp.

An example:
Set the gain to 0.5 (this multiplies the Y' channel by 0.5)

The image will look over-saturated. This is because Y'CbCr color uses color difference components.... if you look into the math (which is just algebra), affecting gain like that will increase saturation. It can even cause negative colors in the R/G/B channels, although these will get clipped so you won't see them in Vegas.

[Dustin Wadsworth]

Awesome, my results are getting better by the minute. Thanks for all the knowledge guys.