ON COLOUR CORRECTION AND VEGAS 6

Jøran Toresen wrote on 2/5/2005, 9:04 PM
Hello

I have just purchased Vegas 5 and realized that the colour correction tools are not as advanced as I thought they should be. Therefore I would appreciate some enhancements in the upcoming version of Vegas.

SOME COLOUR THEORY
In the RGB colour system, pure black is described by the RGB vector (000, 000, 000), pure white is described by the vector (255, 255, 255). And “pure” grey can be described by the middle point vector (127, 127, 127), although in Vegas it is defined by the vector (128. 128, 128) – look at Media Generators, Solid Colour.

I believe that a black and white photo / frame can be described by a continuum of all “parallel” vectors such that each point / pixel can be described by the vectors (000, 000, 000), (001, 001, 001), …, (254, 254, 254), (255, 255, 255).

Here are the mathematical vector values defining the main colours in the RGB and the CMYK colour systems.

Primary colours in the RGB colour system are defined by:
Red = (255, 000, 000)
Green = (000, 255, 000)
Blue = (000, 000, 255)

In the CMYK colour system the complementary colours to the primary colours in the RGB colour system are defined by (look at the colour wheel):

Cyan = (000, 255, 25 5) complementary to red
Magenta = (255, 000, 255) complementary to green
Yellow = (255, 255, 000) complementary to blue

The grey scales is a continuum, but the main “colours” can be defined by the end points black and white and the middle point “pure” grey:

Black = (000, 000, 000)
White = (255, 255, 255)
Grey = (128, 128, 128)

These values are helpful when you want to correct colours in your videos. Therefore I’ve specified them here. For example, if you want to reduce a yellow colour cast, which is a frequently occurring problem, you can simultaneously reduce the values of red and green if you are using the RGB colour system.

THE PROBLEM WITH “GREY” COLOURS
In many or most pictures / videos there are some areas that can be defined as “grey”, where the “colour” grey in principle is ranging from (001, 001, 001) up to (254, 254, 254) in the RGB colour system.

In the real world, subjectively we will perceive a RANGE of vectors as white, respectively black. You can hardly see the difference between the pure white vector (255, 255, 255) and the “grey” vector (240, 240, 240). Nor can you se any difference between the pure black vector (000, 000, 000) and the “grey” vector (010, 010, 010). In Vegas you can check this using Media Generator, Solid Colour, and plotting in the values above.

If the pure white points / areas in your pictures (real world), actually has the vector value (240, 240, 200) in the video you are editing, the same areas – or more likely: the whole video / picture – has a yellow cast / tint. When you adjust the white balance, the colour values of these areas are (in principle) adjusted to the true white vector value (255, 255, 255) – at the same time as ALL the other colour values are changed. Therefore ALL THE COLOURS IN THE PICTURE ARE CHANGED WHEN YOU ADJUST THE WHITE BALANCE. The same happens when you adjust the black balance. Therefore, when you adjust the black balance, all the colours in the picture are changed.

PROBLEMS WITH THE COLOUR CORRECTING TOOLS IN VEGAS 5
What I’m missing in Vegas 5, is a feature that can adjust the “grey balance” – or any colour that is erroneous – in the same way as it is possible to correct the white and black balance. For example, an area that in the real word is “pure” grey, may in your video be described by the vector (128, 128, 160). In other words, the areas that should be “pure” grey are rather bluish. This creates a colour cast to the whole picture, not just the parts that should be “grey”. And to perform the “grey” balance adjustment, all the colours must be changed. In the same way as all colours are changed when the white and black balance is corrected.

As a consequence of the above mentioned problem, I miss an EYEDROPPER feature / tool where I can map the correct colour (for example grey) in ONE image (a frame in a video shot by another camera or a still image) into ANOTHER corresponding area of the frame (video) I’m actually editing. In this way I can (in principle) correct the white balance, the black balance, the grey balance and all other colour casts that might exist in the video I’m editing.

In principle I can perform this operation in Adobe Premiere Elements, but in practice it’s hard to accomplish. So I’m looking forward to the day when Sony is coming up with a similar, but much better functioning feature, in the next version of Vegas. Or do I have to bye a separate colour correction tool that costs more than Vegas…?

Regards,
Joran – Norway

PS. I hope you apologize if my English isn’t as good as it should be, but I hope you understand the essence of my contribution. I’ve deliberately used capitals to emphasize important points and in headings.

Comments

Grazie wrote on 2/5/2005, 9:24 PM
Joran! Thanks for the post! - I use CC a lot . . I don't know enough to reply, but I am listening to this thread and would hope that those that "know" vastly more than I do will chip in here. I'd like to hear a response too.

Your English? No problems for me, I can understand you completely :)

Best regards,

Grazie
filmy wrote on 2/5/2005, 11:09 PM
You might do a search - BillyBoy had posted an excellent little 'how to' that covered some of the topics you mention. And unless I am misunderstanding you, the topic of matching color from shot to shot has also been discussed - again, do a search.
Jay Gladwell wrote on 2/6/2005, 6:00 AM
Joran, the color correction is Vegas is advanced! What you're talking about is the graphics world, i.e., Photoshop. Color correcting video is totally different.

Jay
BillyBoy wrote on 2/6/2005, 7:23 AM
First off in the RGB world of color while 0,0,0 is black and 255,255,255 is white, since 255 can not be divided equally, and there isn't a way to define 127.5 as some exact middle point or as some imaginary "gray point" either the value127 or 128 would be considered accurate as to the middle of the range.

Second, I have no idea why you injected CMYK color into the discussion The CMYK color space is primarally for print media. The problem when working with color on computers is they can be "out of gamut" which simply means a color falls outside the range of the device's color space. A printer, scanner, computer monitor, TV display, digital camera and printing press likely all have different color spaces or limits on how shades of some colors will be reproduced.

The problem is if some of your colors as seen on your computer screen are out of gamut, and you send off something to a printer, some colors can end up looking pretty ugly. Photoshop for example has tools to warn when colors are out of gamut.

Vegas uses the three color RGB system. However as its endlessly been pointed out any color correction should be made while viewing an external monitor so to as much as possible "see" colors as they will be reproduced on either the NTSC or PAL systems assuming your final work is to be viewed off a TV, if not, then you don't of course.

I have no idea what you're trying to accomplish by finding some phantom gray point. The proper method is to remove color cast from both extremes of the range. In other words if you make your black and white points "pure" or free from any preceived color cast, then everything else should fall into place. The middle Color Wheel on the Color Corrector filter adjust midtones. Its primary purpose is to typically fudge colors, usually skin tones so AFTER you set white and black points you can tweak the image making it either warmer or cooler. So if your colors look "bluish" then simply nudge the middle color wheel up and left a tad and it disappears.

You don't have to buy anything else. It does take some practice to make very fine adjustments. I'm guessing I've spend hundreds of hours using this filter and gotten pretty good at it. You can too.
Jay Gladwell wrote on 2/6/2005, 7:48 AM
It does take some practice to make very fine adjustments.

I second Bill's remark. Having gone through his tutorial and practicing (maybe not humdres of hours) I too have learned that it's done in "small moves." It takes finesse, and that takes practice.

Jay
clyde2004 wrote on 2/6/2005, 8:21 AM
"First off in the RGB world of color while 0,0,0 is black and 255,255,255 is white, since 255 can not be divided equally, and there isn't a way to define 127.5 as some exact middle point or as some imaginary "gray point" either the value127 or 128 would be considered accurate as to the middle of the range."

0 to 255 = 256 'units'; 256/2 = 128 'units'. No?
BillyBoy wrote on 2/6/2005, 8:26 AM
Oops... me bad. I forgot in the binary world zero counts as a number.
Stil, if anyone can tell a difference between moving the slider from 127 and 128 they got better eyesight then I do or 99.99% of the population.
BillyBoy wrote on 2/6/2005, 8:31 AM
Hmm... because in the binary world zero doesn't mean "nothing" but actually represents "1" is this the reason dropping a FX filter like blur or sharpen adds a "little" adjustment? Inquiring minds need to know...

I'm so confused, I've fallen and can't get up.
emeli wrote on 2/6/2005, 11:43 AM
You were right before Billy.

There are an even number of integers in the range 0-255. As such, the mid-point is not an integer. It can be called either 127 or 128.

To illustrate, the number sequence 1,2,3,4 has an even number of integers (four). It's midpoint is not an integer (2.5).

The sequence, 1,2,3 has an odd number of integers. It has an integer as a midpoint (2).

256/2 gives 128 which is the number of integers above and below the mid-point. It does not give the mid-point.
Hulk wrote on 2/6/2005, 1:03 PM
Joran,

Hi. You seem to know a lot about color correction. Please don't take this the wrong way but I'm curious as to why you purchased Vegas 5 before checking out the color correction?

A fully functioning demo is available for 30 days. There really was no reason to risk buying before trying.

- Mark
Chienworks wrote on 2/6/2005, 1:23 PM
BillyBoy, just getting the white and black points white does not guarantee correct colors throughout the range. This may get you close in analog video, but in digital this can happen simply by increasing the contrast to blow out the whites and blacks without correcting the color. There are any number of paths to get the brightest part of the image to 255,255,255 (or 240,240,240) without properly adjusting the rest of the colors. The difficulty is that physical colorspace when captured on any medium resembles more a pair of cones, one rightside up on top of the other, upsidedown, than it does a cylinder. Assume the vertical axis is brightness, the angle around is the hue, and the distance from the vertical axis is the saturation. The closer you approach black or white, the less saturation you are capable of achieving, and the less hue information you have. At full white or black, there is no hue or saturation at all. Increase any color's brightness enough in any media and it simply becomes white (unlike in the real world). Colors that are close to white are harder or nearly impossible to tell apart than colors near the middle range. With middle range colors you can get much finer precision because there is more data to work with.

It really is a good idea to use a neutral grey point when adjusting. Color photographers have done this for generations by photographing a grey card in one of the pictures of each shoot, then balancing the prints from this. It is much more accurate and useful than trying to adjust the whites or blacks, especially since it is possible to have a scene that doesn't contain either.

True, this may not be as practical in video, but if given the choice, i would prefer each video take to have a grey card at the beginning.
Chienworks wrote on 2/6/2005, 1:28 PM
Joran, this is just a fine point, but the values you listed for cyan, magenta, and yellow are not in CMYK. You listed the RGB values for them. CMYK values have four vectors, not three. In CMYK space you would have:
cyan = 255, 0, 0, 0
magenta = 0, 255, 0, 0
yellow = 0, 0, 255, 0
red = 0, 255, 255, 0
green = 255, 0, 255, 0
blue = 255, 255, 0, 0
white = 0, 0, 0, 0
grey = 0, 0, 0, 127.5
black = 0, 0, 0, 255
Jøran Toresen wrote on 2/6/2005, 2:38 PM
Hello BillyBoy and all others

First of all, the Colour correction tools in Vegas are great! So are the different Scopes. My main point is that they can be better. I posted this because there’s a discussion concerning the enhancement people wants for the upcoming version of Vegas. And I would like an eyedropper functioning in the way I have described.

1. I wanted to illustrate numerically my discussion. Therefore I wanted to demonstrate how the primary colours in the RGB colour system are defined. And I wanted to show how the complementary colours to the colours in the RGB colour system are defined. This is the primary colours in the CMYK colour system.

2. The colours in the physical display on your computer are generated using the RGB colours. But of course you can use the CMYK colour system when you, using software, are correcting colours. Take a look at TMPGEnc Xpress 3 and the colour correction filter. There you can choose between RGB, YUV, CMYK and HSL.

3. And, the values of the primary colours in the CMYK colour system are of interest because they are shown in the colour wheels in Vegas’ colour correctors.

4. BillyBoy, I’ve read all your tutorials on colour correction and I’ve learned a lot from your contribution! But, as your Tutorial 9 “Matching Levels and Colors from Different Sources”, shows, it is difficult to match colours from different sources using Vegas. It’s not impossible, but it’s difficult – and time consuming.

5. You write in your tutorial 9. “As a first step, see what the two shots have in common. In this example all that's the same are the subjects! The walls, the stage floor, even the pianist's shirt are very different, making it hard to have a starting point to adjust off of. Thankfully, Dave sent me some similar shots so I could get a better idea of the wall and floor coloring.”

6. This is what I’m asking for: Would it not be nice and time saving, if you had an eyedropper tool where you could map the (more) correct colours in the pictures Dave sent to you, into the videos you are editing?

7. Mark, I bought Vegas because I like the program. And I downloaded the demo before buying. But as all other users, I want extra features. I also wish I could move the timeline, in the same way as I can move the preview window etc.

8. Chienworks. I intentionally listed the RGB values for the CMYK colours because I wanted to show the connection between the two systems. But of course, you are right concerning the “correct” values of the CMYK colours.

Have a nice day,
Joran - Norway
BillyBoy wrote on 2/6/2005, 2:38 PM
"BillyBoy, just getting the white and black points white does not guarantee correct colors throughout the range"

I would never try to get the black point WHITE as you suggested. That would cause a very flat looking image.

LOL!
Coursedesign wrote on 2/6/2005, 2:58 PM
You may like the 6cc six vector color corrector for Vegas.

It lets you adjust both RGB and CMY at the same time, and it's free.
Jøran Toresen wrote on 2/6/2005, 3:05 PM
Coursedesign

I’ve already installed the 6CC filter. And this filter illustrates why it is of interest also to specify the RGB values of the colours in the CMYK system when discussing colour correction.

Joran – Norway
Chienworks wrote on 2/6/2005, 3:26 PM
BillyBoy: ok, so i meant to say get the white points white and the black points black.
Jøran Toresen wrote on 2/7/2005, 5:14 PM
Hello everybody

In Adobe Premiere Pro there is a colour correction tool that let you correct the white balance, the black balance and the grey balance. If you buy the US $595 colour correction plug-in “Color Finesse” from Synthetic Aperture, you get a similar feature. Therefore I must ask you veterans

1. Why do you get so annoyed when I, in a constructive way, try to to point at some shortcomings concerning the colour correcting tools in Vegas 5?

2. And to you BillyBoy in particular, why don’t you respond to my thorough and polite answer, when you get so upset from what I’m writing?

Have a nice day,
Joran – Norway
Spot|DSE wrote on 2/7/2005, 5:29 PM
Joran, the Synthetic Aperture tool for Premiere is indeed very nice. Personally, I don't at all like the way Premiere uses the 3 point correction system, but I can see how some users might like it.

Most folks here are fine with the question, just some get testy now and then. Stick around, and welcome to the Vegas community.
Jøran Toresen wrote on 2/7/2005, 6:04 PM
Spot, thank you for your answer

Ok, people get testy – or irritated as I would call it. But, in several threads people say this is the ”best” and most open minded and constructive forum out there. Then, why do some people just trough out their annoyance – and don’t even try to respond in a constructive and polite way when I’m trying to correct their answers?

Vegas IS a good program and therefore I purchased it after testing the free download. But of causes, it can be improved in several ways. Therefore I’m a little bit disappointed when I’m faced with a response from the “veterans” that in fact is telling me that I’m an idiot, which I’m certainly not.

And then to your personal opinion, I quote: “Personally, I don't at all like the way Premiere uses the 3 point correction system, but I can see how some users might like it.” I don’t like it either, but I wish there could be a more easy way to correct the colour scheme shot with different cameras, and – as a special case – a way to correct the “grey” balance in my shots.

By the way, I’m very fond of your books on Vegas 5!

Regards,
Joran – Norway
BillyBoy wrote on 2/7/2005, 7:15 PM
As far a having a color eye dropper tool that reports RGB values, I agree that would be a nice feature like in Photoshop. Why its not part of all color adjustment filters I don't know.

About a couple years ago I mentioned a way to use the RGB eye dropper that is part of some Color filters now in Vegas. While a clumsy way to go about it, if you want to sample a area of color so you can attempt to match it more precisely try this:

1. Add a new video track.
2. Drop any FX filter like Gradient Map that has a RGB eye dropper on the EMPTY track*
3. Set cursor to the frame you wish to "sample", click in preview window.
4. the filter will reflect the RGB values.

* dropping a FX filter on a empty track still lets you use it on another track. The idea behind dropping it on a empty track is by using it you won't mess up your project.