Color Correction help, Please

DelCallo wrote on 5/10/2005, 1:18 AM
BillyBoy and others, I've been working to perfect my color correction skills in Vegas. I recently did a three-cam outdoor shoot and have been applying techniques discussed on BB's site to correct areas where my cams' (one digital, two hi-8) auto exposure, influenced by the colors in the scene, temporarily stopped down the iris to produce video that is too dark.

My camera equipment is neither up-to-date nor particularly expensive (one Sony Digi8, a Sony Hi8 Palmcorder, and an old-but-I-just-like-her Hi8 Sony CCDV5000).

All seem to overcorrect for white backgrounds interrupted by dark foreground objects (like people) moving through the scene.

I try to anticipate and correct for this phenomenon by altering my composition during the taping, but one can only do so much. Fiddling with manual iris controls has proven even more unsatisfying, as I usually end up with wildly sporadic variations in exposure, and even the "correct" exposure is no better than what I can achieve in post with Vegas.

So, (sorry to be so lengthy, here) my question is this: I have worked through the footage from one of the cams per BB's tutorial, and the results, viewed on my computer screen, are just perfect, absolutely exactly what I am looking for.

Previewed externally, however, the results are grainy - the images simply not as high quality as the same footage uncorrected for exposure.

What, if anything, can I do to improve the final results to eliminate this grainy, noisy appearance?

It seems to me that, if the results can look good on my computer monitor, then, the information is there to produce a decent looking image on an external monitor. I must be doing something wrong.

Note that, the corrections I'm making, IMO, do not attempt to correct grossly underexposed footage - for example, I'm shooting closeups of a gal being "made up" for the video "shoot." Subject is seated in a chair outside on a sunny day. The make-up person is wearing a black T-shirt. When that T-shirt enters even a portion of the scene, the cam opens up and my subject is exposed perfectly. When the "T-shirt" steps out of the frame, the cam's iris closes so that the subject, sitting in bright sunlight, is now a bit underexposed.

I am open to suggestions as to better camera technique to avoid this problem from the onset, but, am mostly interested in suggestions as to how I can improve my use of Vegas' editing tools to make my Vegas corrections look better upon output to DV tape or DVD.

Thanks in advance for any advice.

Caruso

Comments

johnmeyer wrote on 5/10/2005, 8:37 AM
What, if anything, can I do to improve the final results to eliminate this grainy, noisy appearance?

ALWAYS do color correction in Vegas through an external monitor. If you color correct using just the computer screen, you are wasting your time.

I can't say it any more plainly.

I think BB's tutorials make this point as well.

Hook up your camcorder and use its pass-through feature to view, in real time, from Vegas, on an external monitor, the results of each color tweak. Also, make sure you have performed monitor calibration prior to doing this, or you are just going to color balance to some "fiction" created by your badly calibrated monitor (which is just a variation on the fiction you have already been balancing to, namely your computer monitor).
BillyBoy wrote on 5/10/2005, 9:27 AM
Also, do you white balance your cameras in the field? This can get to be a bit problematical if different makes, models when trying to blend the source in your final production from several cameras. One issue, sometimes overlooked is color tempature or the relative strength of the light source. You need to take into consideration the difference between indoor/outdoor lighting, ie incandescent and fluorescent lighting, also how bright a day it is, where the sun is, time of day, etc, etc.

There are several hardware/software methods, but you can also do it manually. There are many tutorials on how to do it the traditional way.
A slighly more controversial method takes one's subjective assement into consideration. Anyone reading this forum knows I march to a different drummer on several issues. This is one of them. So for those that dare to push the envelope or want a different view check out this interesting web page that uses something called "warmcards" or how to take the human factor into consideration when doing "white" balance.

http://www.warmcards.com/digital_camera.html

The more traditional tutorial linked on above page is also useful.

http://www.warmcards.com/wb101.html



Spot|DSE wrote on 5/10/2005, 9:31 AM
I don't know that I'd call Doug Jensen's Warmcards as being "nontraditional." Not only do we use these at Sundance, but VASST promotes them on the training tours. These are fabulous tools.
Micheal Morlan has an excellent article on how he uses these.
http://www.vasst.com/search.aspx?text=white%20balance
GlennChan wrote on 5/10/2005, 11:13 AM
1- Shooting the footage nicely in the first place makes your life so much easier.

Setting exposure manually would be nice. On prosumer cameras, they have a button which lets you engage auto-exposure temporarily. With them, engage the autoWB when lighting changes. This way exposure doesn't change during a shot. Sometimes you need to manually set exposure to compensate for back lighting or high contrast lighting (where subject is too bright).

White balanace: WB all three cameras to the same white balance point and leave them there. You just need something white (not everything is white). The key is to disable auto-WB!

To WB: Zoom in on the white card so that it fills the frame. Some viewfinders don't show the whole frame the camera records. Engage the white balance feature of your camera (not all of them have it unfortunately; on some cam's, it called white balance hold). If they don't have that setting, try to disable auto-WB and use a preset (i.e. the "outdoor" one). In Vegas, you can correct WB with media FX. If white balance changes, then one filter won't fix things. So disable auto-white balance if you can.

WB changes as the day goes on... you might want to try doing a re-WB every few hours or so, and change tapes too.

3- Fixing things in post is not fun, especially if you have to tweak every single shot.

Auto levels from mikecrash might kind of help.
http://mikecrash.wz.cz/vegas/vegas.htm
DelCallo wrote on 5/12/2005, 1:39 AM
I appreciate every reply, truly, I do.
But my current problem isn't with white balance, manual exposure (one of my cams has manual exposure, but, I'm not sure it's really manual exposure more than manual iris overide - I'll experiment with that a bit - usually, I find that manually opening the iris is hard to control (the control on the cam is not precise enough), and the result is some grossly over-exposed washed out image - but, I'll check that out) or external preview (I'm doing that as I go and it is the reason I know to post this question).

Whether I like it or not, my current problem is that I have footage that in spots is underexposed. I was, perhaps, a bit misleading when I mentioned that I can get everything to look good on my computer screen - but, I am also checking on my external monitor.

My real problem is that, it seems, no matter what correction I make, the end result is snowy (much more snowy) when viewed on my external monitor than the same footage viewed externally prior to color correction.

I have to be missing something here, because, if everyone were getting similar results, no one would use the feature.

I'm sorry if my question wasn't clear enough or misleading, but I do need help with this snow issue.

The adjustments I'm making aren't that severe (I don't think). Just enough color correction to brighten the subjects face where other elements in the scene caused the cam's iris to stop down.

Thanks again for your replies - please, if you will, give it another go.

Caruso
farss wrote on 5/12/2005, 3:47 AM
First thing to do is to see if your raw footage has the same amount of noise looking at it the same way.
Assuming it didn't or it wasn't as bad I suspect the issue is how CC works, by pushing up the gain on the channels and more gain will make noise more noticable. One way to reduce this perhaps is to not apply any CC in the lowlights.
Bob.
DelCallo wrote on 5/13/2005, 2:00 AM
Bob:
I rendered a version without color correction - no more snow. The video is clear and crisp. Given a choice, I'll either live with those areas that are slightly dark, or edit them out of my final version - hate to do that, because there is some precious footage in those dark areas, but, I can't live with the snow.

I'm not certain what you mean by no applying gain in the lowlights. Perhaps you would be so kind as to explain it further and what I do with the color corrector to try it out.

Thanks.

Caruso
farss wrote on 5/13/2005, 4:38 AM
The CC tool has three color wheels. The left one is for the lowlights, middle for the mids and right for the highlights. So the left most one is going to affect those parts that are black and that's oftenly where the most noise is or where it's most obvious. So if you don't correct the blacks things maybe a bit better.
If you've had to increase the gain in the CC FX that'll also make matters worse.
But with problem footage (I used to work a lot with very bad 8mm) you can make things to look a lot better if you just focus on the things that the eye thinks important, maybe if you don't try to get the CC 100% correct or get all the shots so they're off but off the same amount it might save the day.
You could try Mike's noise reduction tool, it's pretty good, in fact excellent value for money being free. I'd try the CC, then the NR and see if that helps.
Of course the bad news is if you're going to put this on a DVD the mpeg-2 encoding will most likely make the noise look even worse.

You didn't mention how you captured this analogue footage, played back in the D8 camera you do get Dynamic Noise Reduction on most models, that can help a bit. The ADVC-300 can also do DNR (they call it 3D noise reduction) as well as 2D (read knock the high frequencies down). If you can't get access to this even the median filter in Vegas can reduce your noise but use it sparingly and be prepared for long render rimes. If a shot has no motion, motion blur will also reduce noise.

Bob.
DelCallo wrote on 5/13/2005, 1:59 PM
Bob:
Thanks for the advice.
I captured this analog video via that Dazzle DVC90. Other than the blurry still problem that I encountered - which turned out not to be the Dazzle but a matter of changing to progressive from lower field first and one other setting (can't remember what it was, and I don't have access to Vegas from here), it seems to capture just as well as if I first dub to the digital 8. Playing back analog tapes in the digital 8 doesn't work for me - I don't know if this cam lays the video down on slightly differenly configured tracks or what, but, when I digitize directly with the digi8 (by playing an anlog tape in it), the video is all scrambled, and the sound is mono.

At any rate, the footage, if digitized and unalgered, looks the same when viewed externally regardless if it was dubbed to digi8 prior to capturing or if it was run in my analog cam through the Dazzle thingy - both look just as good when played back as they do when the original tape is played to my external monitor via S-connection from my analog cam. I'd say that I got lucky with that Dazzle deal, as, for $75.00, it looks as though it will do the job for me and save me quite a lot of time.

One of these days, I'll problby buy something Canopus, but not for now.

Using the gain is one of the procedures suggested by Billy Boy.

I'll keep playing with things and see what I can learn.

In reality, none of the video is all that bad. There are just a few spots where things get really dark for a moment or two - then, I started correcting, and probably got carried away. It wasn't long until I'd found a reason to apply some degree of correction to every inch of that footage.

I removed all correction and rendered, then printed, and, have to admit, it realy isn't all that bad - but I intend to keep on playing with it.

My client wants 100 copies of the final DVD, so, I want to make it as good as it can be.

Thanks again for your advice.

Caruso
apit34356 wrote on 5/13/2005, 2:15 PM
Delcallo,"Using the gain is one of the procedures suggested by Billy Boy." are you sure? I believe gamma adjustment is the preferred method first.
BillyBoy wrote on 5/13/2005, 4:11 PM
Actually I recommend a combinaiton of Gamma, Gain and Color Curves. It really boils down to how severe a correction you're making, what you're correcting, etc.. No one method works for every source file. For best results break into similar events and apply what each event needs. Attempting one fix using the same settings to an entire project rarely gives the best results. If you want to be extra finiciky, getting in the habit of watching the scopes while adjusting gives still better results. Its amazing how just a little tweak here and there can bring out hidden details. Much like Photoshop, you really don't know how powerful it is until you start using its more powerful tools like curves and levels. For Vegas, the key to superior resuilts is its outstanding Color Corrector filters and Color Curves.
farss wrote on 5/13/2005, 4:21 PM
Certainly all of what BB says is correct however as you're seeing there are limits, even the very best DV can not be pushed very far before things go wrong. As I said don't get too focussed on making it perfect, I'd certainly watch the scopes but also to see where you're starting from. If the source is only pushing 25% then trying to push it to 100% is asking for trouble. A little goes a long way visually.
Bob.
DelCallo wrote on 5/14/2005, 12:24 AM
Yup, I'm pretty certain of Billy Boy's instructions, having perused his tutorials thoroughly. I'm still confused as to what sort of quality everyone else is getting (compared to mine) when they attempt color correction.

As I've stated previously, I'm not attempting huge corrections, here. The source material isn't bad - just too dark in a few areas.

I could (actually, I probably will) simply edit out the offending areas to expedite completion of the project. However, I'd really like to master the Vegas color corection tool - and this footage seems the perfect specimen.

I simply find it hard to accept that the results of the users responding to me on this thread are as objectionable as mine. As soon as I make a correction, the sourde goes from being crystal clear to super grainy. What the @#$% am I doing wrong, here?

Per BB's suggestion, I'm working on just small chunks of the project at a time.

Also, somehow, the "Ignore FX" option got checked in my preview settings, and I cannot get it unchecked. I can select left or right, then manually constrain the ignore FX portion to a teeny rectangle, but, cannot select ALL or uncheck the FX bypassed option. So long as this option is selected, I cannot preview any of my color correction efforts at all. Woe is me! This just cropped up tonight - oh, woe is me.

Caruso
BillyBoy wrote on 5/14/2005, 6:53 AM
Maybe we're talking apples and oranges? Color correction is exactly that, removing unwanted color tint, changing the hue, etc.. If the problem is overly dark video, over doing the gain or pushing the gamma too high or changing curves too much can result in other issues. Can you post a before and after sample?
vitalforce wrote on 5/14/2005, 7:53 AM
This may not help but it worked on my footage. If you apply a Curves FX filter in Vegas, double-click at the midpoint of the diagonal line on the Curves graph, then double-click again and make another point in the lower third of that line. Then make an S-curve on the lower point, in the blacks, and see if that brings out some detail without overemphasizing the noise.