Crushing Blacks Precisely - LOG and Curves in Resolve

The Zone System is a method of precisely identifying levels on the value scale from 0 (pure black) to 10 (pure white). It was created by two photographers, Ansel Adams and Fred Archer, around 1939 or 1940 as a tool that would allow them to ‘previsualize’ a final printed image before even exposing film.  

As a photography student many years ago learning to work with B/W film, it was the single most important tool I had in my conceptual arsenal. With that, I could make monochrome do anything. Without it, it was hit or miss. Mostly miss.

We’re going to use the Zone System, Curves and the LOG Menu to look at ‘crushing blacks’, a common term in film referring to depth of detail in shadow and the exact point at which detail falls off into an inky, detail-less void.

Often, blacks are ‘crushed’ with what seems to be a large, blunt instrument. It doesn’t have to be that way. Resolve gives a colorist a great deal of control over lower values. For example, looking at the chart at the beginning of this post, where - exactly - do we want to lose detail? Should we crush Zone 1 into Zone 0? Or should we go farther and crush Zone 2 down to Zone 0? Should we maintain an appreciable difference between Zone 2 and Zone 3? Or do we crush Zone 3 into Zone 2 and everything below that down to 0? 

Any of those decisions will have an impact on your film, how it feels, how it affects the sense of light. In the still above from Inside Llewen Davis, everything below Zone 3 is crushed into Zone 0, while still maintaining separation through the middle zones and a very high key outside the window. It’s an achievement.

How is this done?

As an example, I’m going to use this frame from a friends’ short film. It’s a similar scene to the Llewen Davis shot.

As we can see in the waveform, most of the data in the image is in the undifferentiated lower values. Our first - and most important task is to spread those values out so that we have something to work with.

The first thing I’m going to do is bring the saturation down to 0, so we are only looking at the tonal values.

In the Primary Wheels menu I’ll use the Gamma Wheel to push the values as far towards the middle of my waveform as I can without losing detail.

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Stretching out the middle tones

My next step is to use the Lift Wheel to drop the shadows. You’ll see immediately that the main effect of these manipulations is to stretch out the midtones in the image, like rolling out a pie crust.

Now we're beginning to see some differentiation in the the very lowest values - Zones 0 - 3.

Here’s how it looks with saturation back up to normal, just for reference.

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Primary Wheels

A brief tangent is required at this point. Until now, we have been working in the Primary Wheels menu - the 'default' color manipulation menu in Resolve. The Primary Wheels controls have an important characteristic which make them ideal for global manipulations - their 'jurisdictions' overlap each other to a very large degree. Because a change to the 'Lift' (lower values) overlaps the 'Gamma' (midtone values) range and even somewhat into the 'Gain' (higher values) range, it means that changes are smooth and blended. For most global changes (like those we have made so far), that's exactly what we want. 

This illustration shows how the Primary Wheels tools work:

But the Primary Wheels tools are not the only tools for manipulating color and tone in Resolve and several of the others are quite different.  At this point in on this shot we need more precise tools, which are available in Resolve in Curves and in the LOG menu. 

[There are others, too, but we'll leave those for another day ...]

Let's say that our objective in working with this specific frame is to separate the lower values and get both rich black and tonal separation in the black T Shirt of the man facing us. We want that shirt to be as pretty as we can make it. Let's look at how we might do that using Curves.

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Y (Luminosity) Curves

The Curves menu looks like this:

By default, the YRGB curves are all active and linked when the Curves menu is selected. By clicking either one of the YRGB buttons at the upper right or the Anchor Icon to the left of them, however, they can be individually selected. 

We want the Y Curve. This curve represents the 'Luminosity' channel and changes only tonality/contrast. This is a very important tool in Resolve because with it, the colorist can change global or local contrast relationships without increasing color saturation. We're going to add points on the curve and change contrast in the lower end of the value scale to bring out the folds in the black T Shirt.

Overall we have deepened the black of the shirt but through the single point raised above the curve we are separating the tones of the folds to make them stand out.

Although it is possible, as shown, to target very specific tonal ranges using Curves, we're still constrained somewhat by the curve itself. Notice that not only were the very lowest ranges affected by the change but so also were others. Curves give you more control than the Primary Wheels, but still not precisely targeted controls.

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LOG Menu

Let's look at the LOG menu.

Although it looks very similar to the Primary Wheels menu, instead of LGG (Lift, Gamma, Gain), the LOG menu has Shadow, Midtone and Highlight. It’s not just the labels that are different, they operate in a very different way, as shown by the following illustration:

The Log menu tools have very little overlap, so it’s possible to control Shadows with very little effect on Midtones or Highlights. Let’s return to our last waveform:

We have now stretched out the value range so there is clear separation between the lower values of the waveform (corresponding, roughly, to Zones 0 - 3). We'll use the LOG Menu to work with those precisely.  My next move will be to use the Shadow control in the LOG menu to drop the lowest values in the waveform to pure black. You’ll note that there is very little change in the overall waveform, only the dropping of the lowest values.

Here’s how it looks with saturation back up to normal:

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Final Tweaks

Although we now have good values in the lowest blacks, and clear separation in the lower Zones, the image still seems a little washed out so we'll return to the Primary Wheels menu, taking advantage of the smoothly blended changes, and tweak it a little bit.

With normal saturation:

Compared to our ungraded image, you’ll see we were able to bring in a full tonal scale - crushing only the blacks we wanted to take to full black - without sacrificing any shadow detail or making the image oppressively dark.



Original, ungraded image:

Happy Grading!

Quick and Dirty Color Balance

Quick and Dirty Color Correction

Here’s a tip for a fast and easy basic color correction in Resolve when there’s nothing obvious to work with. If you can find anything in the dominant light of the frame which should be neutral (white, neutral gray) - no matter how small - you can remove color casts easily.

Here’s our starting point:

Green and dark….

All we’re going to do is isolate one of the white diagonals on the clap board using a power window, like this:

Then we’ll use Gain in the Primary Wheels to wiggle it a little bit so that we can find our selection on the RGB Parade. At first, the Parade looks like this:

But with a little manipulation, we easily see our selection:

All we need to to do now is use the Primary Wheels to level the selection across the Parade …

...remove the Power Window (by clicking again on the selection). Voila! We have a quick rough color balance:

Addendum:

Another method which sometimes (but not always) makes it easier to see your selection is to use Shift-H after you have selected the area you'll be balancing. While this won't help with your viewer window, which will look like this: 

it will have the effect of focusing your RGB Parade on the selection only:

which can make it easier to balance.

Yup. It’s that easy. Happy Grading!

Orange and Teal

The Orange and Teal Thing

You may have heard people commenting on the fact that many movies - especially big features - seem to be always color graded blue and orange. You may even think this is a new phenomenon. You would be mistaken.

The fact is that orange and teal is not ‘new’. It’s not even ‘recent’. In fact, picture makers have been going to this solution for complex images (moving images are inherently complex) for … hundreds and hundreds of years.

Doubt me? I’ll give you some examples. Let’s take Gericault’s masterpiece, The Raft Of The Medusa, 1819.

Now let’s take away the red, to clarify.

What’s left? Orange and teal. The red serves as a jolt of strong, saturated color that spices up the image and gives the impression of a full spectrum. Without it, though, we clearly see how limited the palette actually is.

Let’s try a Rubens. Allegory on the Blessings of Peace, 1630

And without the red…

Procession to Calvary, Pieter Breugel the Elder, 1563

I’ll let you do this one yourself.

And you might know this one, from 1506. Leonardo didn’t even bother with the red.

For a more contemporary example - no one does the red thing better than Marvel.

Do all paintings, or even old master paintings use this strategy? No, but an astonishing number of them do (just look for it) and here’s why. Orange/gold is very flattering in representing people. It’s a logical place to start. Orange and teal are opposites on the hue wheel. That contrast implies a full spectrum, especially when red is added. It looks like a richer palette than it really is but it’s much easier to control.

Nearly all visual art (including film) uses some strategy of palette narrowing or limitation, however, and you’ll find more about that here.

Happy Grading!

Hue, Saturation and Value in Color Grading

If you color grade in film or video you are probably familiar with the terms Hue, Saturation and Value.

[Value is also sometimes referred to as Luminance. Although there are some slight differences between their definitions, in practical use they are synonymous. We can argue about it some other time.]

These are the three attributes of color. In order to manipulate color methodically or precisely an artist or colorist must be fluent with them.

Hue is the location on what we commonly call a color wheel:

Saturation is the relative strength of the color:

Value is the relative lightness/darkness of the color:

[Note: The above illustration is derived from The Zone System, developed by Ansel Adams and Fred Archer around 1939. Anyone working with either shooting film/video or color correction and grading should be on intimate terms with it.]

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Color Correction

The intersection of these three attributes creates what we call color. ‘Color’, however, is too vague a term to be of much use by itself. The more you can think in terms of color attributes, the more clearly you will think about the work you are doing.

Most of us are attentive to these attributes in the process of color correction or primary corrections, so let’s consider the best workflow. The acronym HSV suggests a workflow sequence, but it’s not a very good one. The best way to approach correcting color (that is, balancing tonal inconsistencies, removing color casts, creating continuity between shots and scenes, etc.) is not ‘HSV’ but ‘VHS'. Instead of first correcting Hue, then Saturation, and finally Value (HSV), it is much easier and more efficient to first correct Value, then Hue, and finally Saturation (VHS).

If you are not a fluent translator of color to values then the best way to begin a correction is to work in monochrome on your first pass through the footage. Then bring saturation back to normal to work through the hues. If, after values and hues have been balanced, there are still issues getting footage to a neutral, matching state, the only remaining variable is saturation. It works.

The following illustration shows the three attributes of individual colors imagined as though they are controlled by sliders. Adjusting these attributes to neutral levels is how I approach color correction.

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Color Grading

Proactive application of this theory in the color grading process (creating a look) can be immensely helpful to the colorist, as it not only encourages the artist to look globally at the shot, the scene or the entire project but also adds structure and methodology to the grading process.

This will not solve everything, but done thoroughly it will create a solid foundation for detailed, contextual tweaks. An important caveat is that color - by itself - doesn’t exist. In a world with only one color, only value and saturation matter. ‘Color’ as we know it only exists in relationships with other colors.

A color which appears ‘green’ to most people in one context will appear ‘brown’ in another and ‘blue’ in yet another. What is clearly emerald green in an OTS may appear aqua in the reverse because of changed relationships with surrounding colors. Globally (a change affecting everything in the frame) modifying the attributes of color in a shot/scene will not always be the final point of a grade. It may still be necessary to modify individual colors to create the color relationships desired, but it will set the stage for those specific modifications and simplify that final stage of the grading process.

When modifying multiple colors in relation to each other the three attributes of color are proportionately connected.  Changing the value of one attribute changes the optimal values of the others. Simply put, more of any one attribute requires less of at least one of the other attributes.

Modified for global color changes, our sliders now look this:

In this version of the sliders you see that the hue spectrum has been replaced by ‘# of hues’ and ‘lightness/darkness’ has been replaced by ‘contrast’ (distance between lightest and darkest values). This reflects the fact that we are no longer simply modifying a single color by its attributes but are now modifying a shot/scene with multiple colors that relate to each other.

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So how does this work in practice? Let’s look at a few examples, starting with a composition containing a wide spectrum of hues. A wide spectrum would require either changing saturation or contrast, maybe both. It might look like this:

In this painting by Pierre Puvis De Chavannes (War, 1867), Chavannes uses precisely this approach of many hues, medium contrast and very low saturation in order to keep compositional unity and focus on the important part of the image:

Another example of the same approach by Chavannes:

This is an approach very commonly used in contemporary film - it is often called ‘the film look’. It has the great advantage of unifying compositions/frames almost effortlessly.

Another approach to the inclusion of a wide spectrum is to suppress the value scale in order to keep a wide spectrum of hues yet retain strong saturation, which would look like this:

The example below is a painting by Paul Signac, Portrait of Felix Feneon, 1890.

Signac is all around the color wheel in this painting but look closely at how he pulls it off. First, note that the value range is very compressed - there is little approaching pure black or pure white. Even the top hat is not pure black but dark gray. All the hues are similarly pushed towards the middle of the value range, even the yellows.

When desaturated, this management of tonal range becomes very obvious:

The values of many of the colors are nearly identical (the reds, yellows and blues on the right, for example).The brightest point is the lily and that is nowhere near pure white. The tonal composition, however, is clearly designed to lead your eye to the center. Note also that all the colors remain very saturated.

This approach is very close to classic Hollywood color: lots of hues, strong saturation, but a carefully compressed value range where nearly all values are pushed toward the middle of the scale. There is a little more of real black to the Hollywood version, but nearly all the other values - including the light on the wall - are pushed towards middle gray.

In all three of these examples from classic Hollywood films, we can see in the gray scale versions exactly where the focal points are through the value composition. In the example at the top (Desk Set), it’s the woman in the center desk. In the 2nd example (Seven Year Itch), it’s the two figures in the center of the frame, in the last (The Man Who Knew Too Much), it’s the three figures in the front, the only points in the frame with real white. In all three we have strong, saturated color, but the color is not distracting because of the strict control of values.

In contemporary film (as well as many contemporary commercials), another approach seen more and more is many hues balanced by both low contrast and low saturation so the final product is very, very flat. Although it is sometimes an appealing look on its own (especially combined with a warm/yellowish wash and lens flare for a retro look) it has the additional advantage of being able to unify nearly any frame or sequence. If you must shoot with little control over location, art direction, stage dressing or production design (as many low budgets and indies must), it is a very forgiving approach to a color grade.

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The practical question is ‘how do I make this theory work for me?’ Obviously when looking at big budget features, these strategies are decided in pre-production but they are also available - and useful - to filmmakers without those resources.

Look at your source material. What problems must be solved? What look best fits the story? Are you struggling with a wide spectrum of hues throughout? Would it be appropriate to solve that problem through limiting saturation and/or value?

Or is it necessary to keep colors saturated and vibrant? In that case, can you push values towards the middle of the scale?

There are dozens of ways to interpret color attributes depending on the source material. These are only a few illustrations of color strategies. In other posts I’ve examined the Orange and Teal approach and the concept of the Limited Palette - a way of controlling the use of very strong color.

Happy Grading!