Apple Color 1.5 User Manual

Color

User Manual

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Welcome to Color9Preface

About Color9 About the Color Documentation10 Additional Resources10

Color Correction Basics13Chapter 1

The Fundamental Color Correction Tasks13 When Does Color Correction Happen?16 Image Encoding Standards23 Basic Color and Imaging Concepts28

Color Correction Workflows35Chapter 2

An Overview of the Color Workflow35 Limitations in Color37 Video Finishing Workflows Using Final Cut Pro39 Importing Projects from Other Video Editing Applications47 Digital Cinema Workflows Using Apple ProRes 444450 Finishing Projects Using RED Media56 Digital Intermediate Workflows Using DPX/Cineon Media65 Using EDLs, Timecode, and Frame Numbers to Conform Projects73

Using the Color Interface77Chapter 3

Setting Up a Control Surface78 Using Onscreen Controls78 Using Organizational Browsers and Bins82 Using Color with One or Two Monitors88

Importing and Managing Projects and Media91Chapter 4

Creating and Opening Projects92 Saving Projects92 Saving and Opening Archives95 Moving Projects from Final Cut Pro to Color95 Importing EDLs101 EDL Import Settings102

Relinking Media104 Importing Media Directly into the Timeline105 Compatible Media Formats106 Moving Projects from Color to Final Cut Pro112 Exporting EDLs114 Reconforming Projects115 Converting Cineon and DPX Image Sequences to QuickTime115 Importing Color Corrections117 Exporting JPEG Images118

Configuring the Setup Room119Chapter 5

The File Browser119 Using the Shots Browser122 The Grades Bin128 The Project Settings Tab129 The Messages Tab135 The User Preferences Tab135

Monitoring Your Project149Chapter 6

The Scopes Window and Preview Display149 Monitoring Broadcast Video Output151 Using Display LUTs153 Monitoring the Still Store159

Timeline Playback, Navigation, and Editing161Chapter 7

Basic Timeline Elements162 Customizing the Timeline Interface163 Working with Tracks165 Selecting the Current Shot166 Timeline Playback166 Zooming In and Out of the Timeline169 Timeline Navigation170 Selecting Shots in the Timeline171 Working with Grades in the Timeline172 The Settings 1 Tab174 The Settings 2 Tab175 Editing Controls and Procedures176

Analyzing Signals Using the Video Scopes183Chapter 8

What Scopes Are Available?183 Video Scope Options185 Analyzing Images Using the Video Scopes187

4 Contents

The Primary In Room207Chapter 9

What Is the Primary In Room Used For?207 Where to Start in the Primary In Room?208 Contrast Adjustment Explained210 Using the Primary Contrast Controls212 Color Casts Explained222 Using Color Balance Controls224 The Curves Controls234 The Basic Tab245 The Advanced Tab249 Using the Auto Balance Button251 The RED Tab252

The Secondaries Room257Chapter 10

What Is the Secondaries Room Used For?258 Where to Start in the Secondaries Room?259 The Enabled Button in the Secondaries Room260 Choosing a Region to Correct Using the HSL Qualifiers261 Controls in the Previews Tab268 Isolating a Region Using the Vignette Controls270 Adjusting the Inside and Outside of a Secondary Operation277 The Secondary Curves Explained278 Reset Controls in the Secondaries Room283

The Color FX Room285Chapter 11

The Color FX Interface Explained286 How to Create Color FX286 Creating Effects in the Color FX Room294 Using Color FX with Interlaced Shots300 Saving Favorite Effects in the Color FX Bin301 Node Reference Guide302

The Primary Out Room313Chapter 12

What Is the Primary Out Room Used For?313 Making Extra Corrections Using the Primary Out Room314 Understanding the Image Processing Pipeline314 Ceiling Controls315

Managing Corrections and Grades317Chapter 13

The Difference Between Corrections and Grades317 Saving and Using Corrections and Grades318 Managing Grades in the Timeline325 Using the Copy To Buttons in the Primary Rooms332

5Contents

Using the Copy Grade and Paste Grade Memory Banks334 Setting a Beauty Grade in the Timeline334 Disabling All Grades335 Managing Grades in the Shots Browser336 Managing a Shot’s Corrections Using Multiple Rooms343

Keyframing347Chapter 14

Why Keyframe an Effect?347 Keyframing Limitations347 How Keyframing Works in Different Rooms349 Working with Keyframes in the Timeline351 Keyframe Interpolation353

The Geometry Room355Chapter 15

Navigating Within the Image Preview355 The Pan & Scan Tab356 The Shapes Tab361 The Tracking Tab370

The Still Store381Chapter 16

Saving Images to the Still Store381 Saving Still Store Images in Subdirectories383 Removing Images from the Still Store383 Recalling Images from the Still Store384 Customizing the Still Store View384

The Render Queue389Chapter 17

About Rendering in Color389 The Render Queue Interface395 How to Render Shots in Your Project396 Rendering Multiple Grades for Each Shot400 Managing Rendered Shots in the Timeline401 Examining the Color Render Log401 Choosing Printing Density When Rendering DPX Media402 Gather Rendered Media403

Calibrating Your Monitor405Appendix A

About Color Bars405 Calibrating Video Monitors with Color Bars405

Keyboard Shortcuts in Color409Appendix B

Project Shortcuts409 Switching Rooms and Windows410 Scopes Window Shortcuts411

6 Contents

Playback and Navigation411 Grade Shortcuts412 Timeline-Specific Shortcuts413 Editing Shortcuts413 Keyframing Shortcuts414 Shortcuts in the Shots Browser414 Shortcuts in the Geometry Room414 Still Store Shortcuts414 Render Queue Shortcuts415

Using Multi-Touch Controls in Color417Appendix C

Multi-Touch Control of the Timeline417 Multi-Touch Control in the Shots Browser417 Multi-Touch Control of the Scopes418 Multi-Touch Control in the Geometry Room418 Multi-Touch Control in the Image Preview of the Scopes Window419

Setting Up a Control Surface421Appendix D

JLCooper Control Surfaces421 Tangent Devices CP100 Control Surface426 Tangent Devices CP200 Series Control Surface429 Customizing Control Surface Sensitivity434

7Contents

Welcome to Color

Welcome to the world of professional video and film grading and manipulation using Color.

This preface covers the following:

• About Color (p. 9)

• About the Color Documentation (p. 10)

• Additional Resources (p. 10)

About Color

Color has been designed from the ground up as a feature-rich color correction environment that complements a wide variety of post-production workflows, whether your project is standard definition, high definition, or a 2K digital intermediate. If you've edited a program using Final Cut Pro, it's easy to send your program to Color for grading and then send it back to Final Cut Pro for final output. However, it's also easy to reconform projects that originate as EDLs from other editing environments.

Preface

Color has the tools that professional colorists demand, including:

• Primary color correction using three-way color balance and contrast controls with individual shadow, midtone, and highlight controls

• Curve controls for detailed color and luma channel adjustments

• Up to eight secondary color correction operations per shot with HSL qualifiers, vignettes, user shapes, and separate adjustments for the inside and outside of each secondary

• Color FX node-based effects for creating custom color effects

• Pan & Scan effects

• Motion tracking that can be used to animate vignettes, user shapes, and other effects

• Broadcast legal settings to guarantee adherence to quality control standards

• Support for color correction–specific control surfaces

• And much, much more

All of these tools are divided among eight individual “rooms” of the Color interface, logically arranged in an order that matches the workflow of most colorists. You use Color to correct, balance, and create stylized “looks” for each shot in your program as the last step in the post-production workflow, giving your programs a final polish previously available only to high-end facilities.

About the Color Documentation

The Color User Manual provides comprehensive information about the application and is written for users of all levels of experience.

• Editors and post-production professionals from other disciplines who are new to the color correction process will find information on how to get started, with detailed explanations of how all controls work, and why they function the way they do.

• Colorists coming to Color from other grading environments can skip ahead to find detailed information about the application’s inner workings and exhaustive parameter-by-parameter explanations for every room of the Color interface.

Additional Resources

The following websites provide general information, updates, and support information about Color, as well as the latest news, resources, and training materials.

Color Website

For more information about Color, go to:

• http://www.apple.com/finalcutstudio/color

Apple Service and Support Websites

The Apple Service and Support website provides software updates and answers to the most frequently asked questions for all Apple products, including Color. You’ll also have access to product specifications, reference documentation, and Apple product technical articles:

• http://www.apple.com/support

For support information that's specific to Color, go to:

• http://www.apple.com/support/color

To provide comments and feedback about Color, go to:

• http://www.apple.com/feedback/color.html

A discussion forum is also available to share information about Color. To participate, go to:

• http://discussions.apple.com

10 Preface Welcome to Color

For more information on the Apple Pro Training Program, go to:

• http://www.apple.com/software/pro/training

11Preface Welcome to Color

Color Correction Basics

To better learn how Color works, it’s important to understand the overall color correction process and how images work their way through post-production in standard definition (SD), high definition (HD), and film workflows.

If you’re new to color correction, the first part of this chapter provides a background in color correction workflows to help you better understand why Color works the way it does. The second part goes on to explain color and imaging concepts that are important to the operation of the Color interface.

This chapter covers the following:

• The Fundamental Color Correction Tasks (p. 13)

• When Does Color Correction Happen? (p. 16)

• Image Encoding Standards (p. 23)

• Basic Color and Imaging Concepts (p. 28)

The Fundamental Color Correction Tasks

In any post-production workflow, color correction is generally one of the last steps taken to finish an edited program. Color has been created to give you precise control over the look of every shot in your project by providing flexible tools and an efficient workspace in which to manipulate the contrast, color, and geometry of each shot in your program.

When color correcting a given program, you’ll be called upon to perform many, if not all, of the tasks described in this section. Color gives you an extensive feature set with which to accomplish all this and more. While the deciding factor in determining how far you go in any color correction session is usually the amount of time you have in which to work, the dedicated color correction interface in Color allows you to work quickly and efficiently.

Every program requires you to take some combination of the following steps.

Stage 1: Correcting Errors in Color Balance and Exposure

Frequently, images that are acquired digitally (whether shot on analog or digital video, or transferred from film) don’t have optimal exposure or color balance to begin with. For example, many camcorders and digital cinema cameras deliberately record blacks that aren’t quite at 0 percent in order to avoid the inadvertent crushing of data unnecessarily.

Furthermore, accidents can happen in any shoot. For example, the crew may not have had the correctly balanced film stock for the conditions in which they were shooting, or someone may have forgotten to white balance the video camera before shooting an interview in an office lit with fluorescent lights, resulting in footage with a greenish tinge. Color makes it easy to fix these kinds of mistakes.

Stage 2: Making Sure That Key Elements in Your Program Look the Way They Should

Every scene of your program has key elements that are the main focus of the viewer. In a narrative or documentary video, the focus is probably on the individuals within each shot. Ina commercial, the key element is undoubtedly the product (for example, the label of a bottle or the color of a car). Regardless of what these key elements are, chances are you or your audience will have certain expectations of what they should look like, and it’s your job to make the colors in the program match what was originally shot.

When working with shots of people, one of the guiding principles of color correction is to make sure that their skin tones in the program look the same as (or better than) in real life. Regardless of ethnicity or complexion, the hues of human skin tones, when measured objectively on a Vectorscope, fall along a fairly narrow range (although the saturation and brightness vary). Color gives you the tools to make whatever adjustments are necessary to ensure that the skin tones of people in your final edited piece look the way they should.

Stage 3: Balancing All the Shots in a Scene to Match

Most edited programs incorporate footage from a variety of sources, shot in multiple locations over the course of many days, weeks, or months of production. Even with the most skilled lighting and camera crews, differences in color and exposure are bound to occur, sometimes within shots meant to be combined into a single scene.

When edited together, these changes in color and lighting can cause individual shots to stand out, making the editing appear uneven. With careful color correction, all the different shots that make up a scene can be balanced to match one another so that they all look as if they’re happening at the same time and in the same place, with the same lighting. This is commonly referred to as scene-to-scene color correction.

Stage 4: Creating Contrast

Color correction can also be used to create contrast between two scenes for a more jarring effect. Imagine cutting from a lush, green jungle scene to a harsh desert landscape with many more reds and yellows. Using color correction, you can subtly accentuate these differences.

14 Chapter 1 Color Correction Basics

Stage 5: Achieving a “Look”

The process of color correction is not simply one of making all the video in your piece match some objective model of exposure. Color, like sound, is a property that, when subtly mixed, can result in an additional level of dramatic control over your program.

With color correction, you can control whether your video has rich, saturated colors or a more muted look. You can make your shots look warmer by pushing their tones into the reds, or make them look cooler by bringing them into the blues. You can pull details out of the shadows, or crush them, increasing the picture’s contrast for a starker look. Such subtle modifications alter the audience’s perception of the scene being played, changing a program’s mood. Once you pick a look for your piece, or even for an individual scene, you can use color correction to make sure that all the shots in the appropriate scenes match the same look, so that they cut together smoothly.

Stage 6: Adhering to Guidelines for Broadcast Legality

If a program is destined for television broadcast, you are usually provided with a set of quality control (QC) guidelines that specify the “legal” limits for minimum black levels, maximum white levels, and minimum and maximum chroma saturation and composite RGB limits. Adherence to these guidelines is important to ensure that the program is accepted for broadcast, as “illegal” values may cause problems when the program is encoded for transmission. QC standards vary, so it’s important to check what these guidelines are in advance. Color has built-in broadcast safe settings (sometimes referred to as a legalizer) that automatically prevent video levels from exceeding the specified limits. For more information, see The Project Settings Tab.

Stage 7: Adjusting Specific Elements Separately

It’s sometimes necessary to selectively target a narrow range of colors to alter or replace only those color values. A common example of this might be to turn a red car blue or to mute the excessive colors of an article of clothing. These sorts of tasks are accomplished with what’s referred to as secondary color correction, and Color provides you with numerous tools with which to achieve such effects. For more information, see The Secondaries

Room.

Stage 8: Making Digital Lighting Adjustments

Sometimes lighting setups that looked right during the shoot don’t work as well in post-production. Changes in the director’s vision, alterations to the tone of the scene as edited, or suggestions on the part of the director of photography (DoP) during post may necessitate alterations to the lighting within a scene beyond simple adjustments to the image’s overall contrast. Color provides powerful controls for user-definable masking which, in combination with secondary color correction controls, allow you to isolate multiple regions within an image and fine-tune the lighting. This is sometimes referred to as digital relighting. For more information, see The Secondaries Room and Controls in

the Shapes Tab.

15Chapter 1 Color Correction Basics

Stage 9: Creating Special Effects

Sometimes a scene requires more extreme effects, such as manipulating colors and exposure intensively to achieve a day-for-night look, creating an altered state for a flashback or hallucination sequence, or just creating something bizarre for a music video. In the Color FX room, Color provides you with an extensible node-based tool set for creating such in-depth composites efficiently, in conjunction with the other primary and secondary tools at your disposal. For more information, see The Color FX Room.

When Does Color Correction Happen?

A program’s color fidelity shouldn’t be neglected until the color correction stage of the post-production process. Ideally, every project is begun with a philosophy of color management that’s applied during the shoot, is maintained throughout the various transfer and editing passes that occur during post-production, and concludes with the final color correction pass conducted in Color. This section elaborates on how film and video images have traditionally made their way through the post-production process. For detailed information, see:

• Color Management Starts During the Shoot

• Initial Color Correction When Transferring Film

• Traditional Means of Final Color Correction

• Advantages of Grading with Color

Color Management Starts During the Shoot

Whether a program is shot using film, video, or high-resolution digital imaging of another means, it’s important to remember that the process of determining a program’s overall look begins when each scene is lit and shot during production. To obtain the maximum amount of control and flexibility over shots in post-production, you ideally should start out with footage that has been exposed with the end goals in mind right from the beginning. Color correction in post-production is no substitute for good lighting.

Optimistically, the process of color correction can be seen as extending and enhancing the vision of the producer, director, and director of photography (DoP) as it was originally conceived. Often, the DoP gets personally involved during the color correction process to ensure that the look he or she was trying to achieve is perfected.

At other times, the director or producer may change his or her mind regarding how the finished piece should look. In these cases, color correction might be used to alter the overall look of the piece (for example, making footage that was shot to look cool look warmer, instead). While Color provides an exceptional degree of control over your footage, it’s still important to start out with clean, properly exposed footage.

16 Chapter 1 Color Correction Basics

Furthermore, choices made during preproduction and the shoot, including the film or

Telecine VideotapesVideotapesCamera Negative

video format and camera settings used, can have a profound effect on the amount of flexibility that’s available during the eventual color correction process.

Initial Color Correction When Transferring Film

When a project has been shot on film, the camera negatives must first be transferred to the videotape or digital video format of choice prior to editing and digital post using a telecine or datacine machine. A telecine is a machine for transferring film to videotape, while a datacine is set up for transferring film directly to a digital format, usually a DPX (Digital Picture eXchange) or Cineon image sequence.

Usually, the colorist running the film transfer session performs some level of color correction to ensure that the editor has the most appropriate picture to work with. The goals of color correction at this stage usually depend on both the length of the project and the post-production workflow that’s been decided upon.

• Short projects, commercials, spots, and very short videos may get a detailed color correction pass right away. The colorist will first calibrate the telecine’s own color corrector to balance the whites, blacks, and color perfectly. Then the colorist, in consultation with the DoP, director, or producer, will work shot by shot to determine the look of each shot according to the needs of the project. As a result, the editor will be working with footage that has already been corrected.

• Long-form projects such as feature-length films and longer televisionprograms probably won’t get a detailed color correction pass right away. Instead, the footage that is run through the telecine will be balanced to have reasonably ideal exposure and color for purposes of having a good image for editing, and left at that. Detailed color correction is then done at another stage.

• Projects of any length that are going through post-production as a digital intermediate are transferred with a color correction pass designed to retain the maximum amount of image data. Since a second (and final) digital color correction pass is intended to be performed at the end of the post-production process, it’s critical that the image data is high quality, preserving as much highlight and shadow detail as possible. Interestingly, since the goal is to preserve the image data and not to create the final look of the program, the highest-quality image for grading may not bethe most visually appealing image.

17Chapter 1 Color Correction Basics

However the color correction is handled during the initial telecine or datacine transfer, once complete, the footage goes through the typical post-production processes of offline and online editorial.

Color Correcting Video Versus Film

Color has been designed to fit into both video and film digital intermediate workflows. Since all footage must first be transferred to a QuickTime or image sequence format to be imported into Color, film and video images are corrected using the same tools and methods.

Three main attributes affect the quality of media used in a program, all of which are determined when the footage is originally captured or transferred prior to Colorimport:

• The type and level of compression applied to the media

• The bit depth at which it’s encoded

• The chroma subsampling ratio used

For color correction, spatial and temporal compression should be minimized, since compression artifacts can compromise the quality of your adjustments. Also, media at higher bit depths is generally preferable (see Bit Depth Explained).

Most importantly of all, high chroma subsampling ratios, such as 4:4:4 or 4:2:2, are preferred to maximize the quality and flexibility of your corrections. There’s nothing stopping you from working with 4:1:1 or 4:2:0 subsampled footage, but you may find that extreme contrast adjustments and smooth secondary selections are a bit more difficult to accomplish with highly compressed color spaces.

For more information, see Chroma Subsampling Explained.

Traditional Means of Final Color Correction

Once editing is complete and the picture is locked, it’s time for color correction (referred to as color grading in the film world) to begin. Traditionally, this process has been accomplished either via a colortiming session for film or via a tape-to-tape color correction session for video.

Color Timing for Film

Programs being finished and color corrected on film traditionally undergo a negative conform process prior to color timing. When editorial is complete, the original camera negative is conformed to match the workprint or video cut of the edited program using a cut list or pull list. (If the program was edited using Final Cut Pro, this can be derived using Cinema Tools.) These lists list each shot used in the edited program and show how each shot fits together. This is a time-consuming and detail-oriented process, since mistakes made while cutting the negative are extremely expensive to correct.

18 Chapter 1 Color Correction Basics

Once the camera negative has been conformed and the different shots physically glued

Conform Negative Final Film PrintOptical Color TimingCamera Negative

together onto alternating A and B rolls, the negative can be color-timed by being run through an optical printer designed for this process. These machines shine filtered light through the original negatives to expose an intermediate positive print, in the process creating a single reel of film that is the color-corrected print.

The process of controlling the color of individual shots and doing scene-to-scene color correction is accomplished with three controls to individually adjust the amount of red, green, and blue light that exposes the film, using a series of optical filters and shutters. Each of the red, green, and blue dials is adjusted in discrete increments called printer points (with each point being a fraction of an f-stop, the scale used to measure film exposure). Typically there’s a total range of 50 points, where point 25 is the original neutral state for that color channel. Increasing or decreasing all three color channels together darkens or brightens the image, while making disproportionate adjustments to the three channels changes the color balance of the image relative to the adjustment.

The machine settings used for each shot can be stored (at one time using paper tape technology) and recalled at any time, to ease subsequent retiming and adjustments, with the printing process being automated once the manual timing is complete. Once the intermediate print has been exposed, it can be developed and the final results projected.

While this system of color correction may seem cumbersome compared to today’s digital tools for image manipulation, it’s an extremely effective means of primary color correction for those who’ve mastered it.

Note: Color includes printer points controls for colorists who are familiar with this method of color correction. For more information, see The Advanced Tab.

Tape-to-Tape Color Correction

For projects shot on videotape (and for those shot on film that will not receive a second telecine pass), the color correction process fits into the traditional video offline/online workflow. Once the edit has been locked, the final master tape is assembled, either by being reconformed on the system originally used to do the offline or by taking the EDL (Edit Decision List) and original source tapes to an online suite compatible with the source tape formats. For more information about EDLs, see Importing Projects from Other Video

Editing Applications.

19Chapter 1 Color Correction Basics

If the online assembly is happening in a high-end online suite, then color correction can

Videotapes

Tape Suite

Final Master TapeOffline Edit

be performed either during the assembly of the master tape or after assembly by running the master tape through a color correction session.

Note: If the final master tape is color corrected, the colorist must carefully dissolve and wipe color correction operations to match video dissolves and wipes happening in the program.

Either way, the video signal is run through dedicated video color correction hardware and software, and the colorist uses the tape’s master timecode to set up and preserve color correction settings for every shot of every scene.

The evolution of the online video color correction suite introduced many more tools to the process, including separate corrections for discrete tonal zones, secondary color correction of specific subjects via keying and shapes controls, and many other creative options.

Color Correcting via a Second Telecine Pass

Programs shot on film that are destined for video mastering, such as for an episodic broadcast series, may end up back in the telecine suite for their final color correction pass. Once editing is complete and the picture is locked, a cut list or pull list (similar to that used for a negative conform) is created that matches the EDL of the edited program.

Using the cut list, the post-production supervisor pulls only the film negative that was actually used in the edit. Since this is usually a minority of the footage that was originally shot, the colorist now has more time (depending on the show’s budget, of course) to perform a more detailed color correction pass on the selected footage that will be assembled into the final video program during this final telecine pass.

Although this process might seem redundant, performing color correction directly from the film negative has several distinct advantages. Since film has greater latitude from black to white than video has, a colorist working straight off the telecine potentially has a wider range of color and exposure from which to draw than when working only with video.

20 Chapter 1 Color Correction Basics

In addition, the color correction equipment available to the telecine colorist has evolved

Camera

Negative

Offline Media Reconform

Final Master

Inexpensive

One-Light

Telecine Pass

Best-Light

Telecine Pass

Offline Edit

to match (and is sometimes identical to) the tools available to online video colorists, with the added advantage that the colorist can work directly on the uncompressed images provided by the telecine.

After the conclusion of the second color correction pass, the color-corrected selects are reassembled to match the original edit, and the project is mastered to tape.

Incidentally, even if you don’t intend to color correct your program in the telecine suite, you might consider retransferring specific shots to make changes that are easier or of higher quality to make directly from the original camera negative. For example, after identifying shots you want to retransfer in your Final Cut Pro sequence, you can use Cinema Tools to create a selects list just for shots you want to optically enlarge, speeding the transfer process.

Other Advantages to Telecine Transfers

In addition to color correction, a colorist working with a telecine has many other options available, depending on what kinds of issues may have come up during the edit.

• Using a telecine to pull the image straight off the film negative, the colorist can reposition the image to include parts of the film image that fall outside of the action safe area of video.

• With the telecine, the image can also be enlarged optically, potentially up to 50 percent without visible distortion.

• The ability to reframe shots in the telecine allows the director or producer to make significant changes to a scene, turning a medium shot into a close-up for dramatic effect, or moving the entire frame up to crop out a microphone that’s inadvertently dropped into the shot.

21Chapter 1 Color Correction Basics

Advantages of Grading with Color

When Does Color Correction Happen? discusses how color correction is accomplished in

other post-production environments. This section describes how Color fits into a typical film or video post-production process.

Color provides many of the same high-end color correction tools on your desktop that were previously available only in high-end tape-to-tape and telecine color correction suites. In addition, Color provides additional tools in the Color FX room that are more commonly found in dedicated compositing applications, which give you even more detailed control over the images in your program. (For more information, see The Color

FX Room.)

Color has been designed as a color correction environment for both film and video. It’s resolution-independent, supporting everything from standard definition video up to 2K and 4K film scans. It also supports multiple media formats and is compatible with image data using a variety of image sequence formats and QuickTime codecs.

Color also has been designed to be incorporated into a digital intermediate workflow. Digital intermediate refers to a high-quality digital version of your program that can be edited, color corrected, and otherwise digitally manipulated using computer hardware and software, instead of tape machines or optical printers.

Editors, effects artists, and colorists who finish video programs in a tapeless fashion have effectively been working with digital intermediates for years, but the term usually describes the process of scanning film frames digitally, for the purposes of doing all edit conforming, effects, and color correction digitally. It is then the digital image data which is printed directly to film or compiled as a file for digital projection.

Finishing film or video programs digitally frees colorists from the limitations of film and tape transport mechanisms, speeding their work by letting them navigate through a project as quickly as they can in a nonlinear editing application. Furthermore, working with the digital image data provides a margin of safety, by eliminating the risk of scratching the negative or damaging the source tapes.

When Does Color Correction in Color Happen?

Color correction using Color usually happens at or near the conclusion of the online edit or project conform, often at the same time the final audio mix is being performed. Waiting until the picture is locked is always a good idea, but it’s not essential, as Color provides tools for synchronizing projects that are still being edited via XML files or EDLs.

Color has been designed to work hand in hand with editing applications like Final Cut Pro; Final Cut Pro takes care of input, editing, and output, and Color allows you to focus on color correction and related effects.

22 Chapter 1 Color Correction Basics

About Importing Projects and Media into Color

To work on a program in Color, you must be provided with two sets of files:

• Final Cut Pro sequence data can be sent to Color directly using the Send To Color command. Otherwise, the edited project file (or files, if the program is in multiple reels) should be provided in a format that can be imported into Color. Compatible formats include Final Cut Pro XML files, and compatible EDL files from nearly any editing environment.

• High-quality digital versions of the original source media, in a compatible QuickTime or image sequence format.

Project and media format flexibility means that Color can be incorporated into a wide variety of post-production workflows. For an overview of different color correction workflows using Color, see Color Correction Workflows.

About Exporting Projects from Color

Color doesn’t handle video capture or output to tape on its own. Once you finish color correcting your project in Color, you render every shot in the project to disk as an alternate set of color-corrected media files, and you then send your Color project back to Final Cut Pro, or hand it off to another facility for tape layoff or film out. For more information, see The Render Queue.

What Footage Does Color Work With?

Color can work with film using scanned DPX or Cineon image sequences, or with video clips using QuickTime files, at a variety of resolutions and compression ratios. This means you have the option of importing and outputting nearly any professional format, from highly compressed standarddefinition QuickTime DV-25 shots upthrough uncompressed 2K or 4K DPX image sequences—whatever your clients provide.

Image Encoding Standards

The sections listed below provide important information about the image encoding standards supported by Color. The image data you’ll be color correcting is typically

encoded either using an RGB or Y′C

extremely flexible and capable of working with image data of either type. For detailed information, see:

• The RGB Additive Color Model Explained

• The Y′C

Color Model Explained

BCR

• Chroma Subsampling Explained

• Bit Depth Explained

(sometimes referred to as YUV) format. Color is

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23Chapter 1 Color Correction Basics

The RGB Additive Color Model Explained

In the RGB color model, three color channels are used to store red, green, and blue values in varying amounts to represent each available color that can be reproduced. Adjusting the relative balance of values in these color channels adjusts the color being represented. When all three values are equal, the result is a neutral tone, from black through gray to white.

More typically, you’ll see these ratios expressed as digital percentages in the Color Parade scope or Histogram. For example, if all three color channels are 0%, the pixel is black. If all three color channels are 50%, the pixel is a neutral gray. If all three color channels are 100% (the maximum value), the pixel is white.

Animation (an older, 8-bit codec) and Apple ProRes 4444 (a newer 10-bit codec) are the two most commonly used RGB QuickTime codecs. In digital intermediate workflows, RGB-encoded images are typically stored as uncompressed DPX or Cineon image sequences.

The Y′C

Video is typically recorded using the Y′C

Color Model Explained

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color model. Y′C

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color coding also employs

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three channels, or components. A shot’s image is divided into one lumacomponent (luma is image luminance modified by gamma for broadcast) and two color difference components which encode the chroma (chrominance). Together, these three components make up the picture that you see when you play back your video.

• The Y′ component represents the black-and-white portion of an image’s tonal range.

Because the eye has different sensitivities to the red, green, and blue portions of the

spectrum, the image “lightness” that the Y′ component reproduces is derived from a

weighted ratio of the (gamma-corrected) R, G, and B color channels. (Incidentally, the

Y′ component is mostly green.) Viewed on its own, the Y′ component is the

monochrome image.

• The two color difference components, CBand CR, are used to encode the color information in such a way as to fit three color channels of image data into two. A bit

of math is used to take advantage of the fact that the Y′ component also stores green

information for the image. The actual math used to derive each color component is C

= B′ - Y′, while CR = R′ - Y′.

Note: This scheme was originally created so that older black-and-whitetelevisions would be compatible with the newer color television transmissions.

Chroma Subsampling Explained

In Y′C

the luma channel. Because the human eye is more sensitive to differences in brightness than in color, this has been used as a way of reducing the video bandwidth (or data rate) requirements without perceptible loss to the image.

encoded video, the color channels are typically sampled at a lower ratio than

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The sampling ratio between the Y′, C

, and CRchannels is notated as a three-value ratio.

There are four common chroma subsampling ratios:

• 4:4:4: 4:4:4 chroma subsampled media encodes completely uncompressed color, the highest quality possible, as the color difference channels are sampled at the same rate as the luma channel. 4:4:4 subsampled image data is typically obtained via telecine or datacine to an image sequence or video format capable of containingit, and is generally employed for digital intermediate and film workflows. RGB encoded images such as DPX and Cineon image sequences and TIFF files are always 4:4:4.

The Apple ProRes 4444 codec lets you capture, transcode to, and master media at this high quality. (The fourth 4 refers to the ability of Apple ProRes 4444 to preserve an uncompressed alpha channel in addition to the three color channels; however, Color doesn’t support alpha channels.)

Be aware that simply rendering at 4:4:4 doesn’t guarantee a high-quality result. If media is not acquired at 4:4:4, then rendering at 4:4:4 will preserve the high quality of corrections you make to the video, but it won’t add color information that wasn’t there to begin with.

As of this writing, few digital acquisition formats are capable of recording 4:4:4 video, but those that do include HDCAM SR, as well as certain digital cinema cameras, including the RED, Thompson Viper FilmStream, and Genesis digital camera systems.

• 4:2:2: 4:2:2 is a chroma subsampling ratio typical for many high-quality standard and high definition video acquisition and mastering formats, including Beta SP (an analog format), Digital Betacam, Beta SX, IMX, DVCPRO 50, DVCPRO HD, HDCAM, and D-5 HD.

Although storing half the color information of 4:4:4, 4:2:2 is standard for video mastering and broadcast. As their names imply, Apple Uncompressed 8-bit 4:2:2, Apple Uncompressed 10-bit 4:2:2, Apple ProRes 422, and Apple ProRes 422 (HQ) all use 4:2:2 chroma subsampling.

• 4:1:1 and 4:2:0: 4:1:1 is typical for consumer and prosumer video formats including DVCPRO 25 (NTSC and PAL), DV, and DVCam (NTSC).

4:2:0 is another consumer-oriented subsampling rate, used by DV (PAL), DVCAM (PAL), and MPEG-2, as well as the high definition HDV and XDCAM HD formats.

Due to their low cost, producers of all types have flocked to these formats for acquisition, despite the resulting limitations during post-production (discussed below). Regardless, whatever the acquisition format, it is inadvisable to master using either 4:1:1 or 4:2:0 video formats.

It’s important to be aware of the advantages of higher chroma subsampling ratios in the color correction process. Whenever you’re in a position to specify the transfer format with which a project will be finished, make sure you ask for the highest-quality format your system can handle. (For more information about high-quality finishing codecs, see A

Tape-Based Workflow.)

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As you can probably guess, more color information is better when doing color correction. For example, when you make large contrast adjustments to 4:1:1 or 4:2:0 subsampled video, video noise in the image can become exaggerated; this happens most often with underexposed footage. You’ll find that you can make the same or greater adjustments to 4:2:2 subsampled video, and the resulting image will have much less grain and noise. Greater contrast with less noise provides for a richer image overall. 4:4:4 allows the most latitude, or flexibility, for making contrast adjustments with a minimum of artifacts and noise.

Furthermore, it’s common to use chroma keying operations to isolate specific areas of the picture for correction. This is done using the HSB qualifiers in the Secondaries room. (For more information, see Choosing a Region to Correct Using the HSL Qualifiers.) These keying operations will have smoother and less noisy edges when you’re working with 4:2:2 or 4:4:4 subsampled video. The chroma compression used by 4:1:1 and 4:2:0 subsampled video results in macroblocks around the edges of the resulting matte when you isolate the chroma, which can cause a “choppy” or “blocky” result in the correction you’re trying to create.

Despite these limitations, it is very possible to color correct highly compressed video. By paying attention to image noise as you stretch the contrast of poorly exposed footage, you can focus your corrections on the areas of the picture where noise is minimized. When doing secondary color correction to make targeted corrections to specific parts of the image, you may find it a bit more time consuming to pull smooth secondary keys. However, with care and patience, you can still achieve beautiful results.

Film Versus Video and Chroma Subsampling

With a bit of care you can color correct nearly any compressed video or image sequence format with excellent results, and Color gives you the flexibility to use highly compressed source formats including DV, HDV, and DVCPRO HD.

Standard and high definition video, on the other hand, is usually recorded with lower chroma subsampling ratios (4:2:2 is typical even with higher-quality video formats, and 4:1:1 and 4:2:0 are common with prosumer formats) and higher compression ratios, depending entirely upon the recording and video capture formats used. Since the selected video format determines compression quality at the time of the shoot, there’s nothing you can do about the lost image data, other than to make the best of what you have.

In general, film footage is usually transferred with the maximum amount of image data possible, especially when transferred as a completely uncompressed image sequence (4:4:4) as part of a carefully managed digital intermediate workflow. This is one reason for the higher quality of the average film workflow.

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Bit Depth Explained

Another factor that affects the quality of video images, and can have an effect on the quality of your image adjustments, is the bit depth of the source media you’re working

with. With both RGB and Y′C

data is available, and the smoother both the image and your corrections will be. The differences between images at different bit depths is most readily apparent in gradients such as skies, where lower bit depths show banding, and higher bit depths do not.

The bit depth of your source media depends largely on how that media was originally acquired. Most of the media you’ll receive falls into one of the following bit depths, all of which Color supports:

• 8-bit: Most standard and high definition consumer and professional digital video formats capture 8-bit image data, including DV and DVCPRO-25, DVCPRO 50, HDV, DVCPRO HD, HDCAM, and so on.

• 10-bit: Many video capture interfaces allow the uncompressed capture of analog and digital video at 10-bit resolution.

• 10-bit log: By storing data logarithmically, rather than linearly, a wider contrast ratio (such as that of film) can be represented by a 10-bit data space. 10-bit log files are often recorded from datacine scans using the Cineon and DPX image sequence formats.

• 12-bit: Some cameras, such as the RED ONE, capture digital images at 12-bit, providing for even smoother transitions in gradients.

• 16-bit: It has been said that it takes 16 bits of linear data to match the contrast ratio that can be stored in a 10-bit log file. Since linear data is easier for computers to process, this is another data space that’s available in some image formats.

• Floating Point: The highest level of image-processing quality available. Refers to the use of floating-point math to store and calculate fractional data. This means that values higher than 1 can be used to store data that would otherwise be rounded down using the integer-based 8-bit, 10-bit, 12-bit, and 16-bit depths. Floating Point is a processor-intensive bit depth to work with.

encoded media, the higher the bit depth, the more image

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Higher bit depths accommodate more image data by using a greater range of numbers to represent the tonal range that’s available. This is apparent when looking at the numeric ranges used by the two bit depths most commonly associated with video.

• 8-bit images use a full range of 0–255 to store each color channel. (Y′C

video uses

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a narrower range of 16–235 to accommodate super-black and super-white.) 255 isn’t a lot of values, and the result can be subtly visible “stairstepping” in areas of the picture with narrow gradients (such as skies).

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• 10-bit images, on the other hand, use a full range of 0 to 1023 to store each color

channel. (Again, Y′C

super-black and super-white.) The additional numeric range allows for smoother gradients and virtually eliminates bit depth–related artifacts.

Fortunately, while you can’t always control the bit depth of your source media, you can control the bit depth at which you work in Color independently. This means that even if the source media is at a lower bit depth, you can work at a higher bit depth to make sure that the quality of your corrections is as high as possible. In particular, many effects and secondary corrections look significantly better when Color is set to render at higher bit depths. For more information, see Playback, Processing, and Output Settings.

video uses a narrower range of 64–940 to accommodate

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Basic Color and Imaging Concepts

Color correction involves controlling both an image’s contrast and its color (exercising separate control over its hue and saturation). This section explains these important imaging concepts so that you can better understand how the Color tools let you alter the image. For detailed information, see:

• Contrast Explained

• Luma Explained

• Gamma Explained

• Chroma Explained

• Primary and Secondary Color Relationships Explained

• The HSL Color Space Model Explained

Contrast Explained

Contrast adjustments are among the most fundamental, and generally the first, adjustments made. Contrast is a way of describing an image’s tonality. If you eliminate all color from an image, reducing it to a series of grayscale tones, the contrast of the picture is seen by the distribution of dark, medium, and light tones in the image.

Controlling contrast involves adjustments to three aspects of an image’s tonality:

• The black point is the darkest pixel in the image.

• The white point is the brightest pixel in the image.

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• The midtones are the distribution of all tonal values in between the black and white

WhiteBlack

Mids

points.

An image’s contrastratio is the difference between the darkest and brightest tonal values within that image. Typically, a higher contrast ratio, where the difference between the two is greater, is preferable to a lower one. Unless you’re specifically going for a low-contrast look, higher contrast ratios generally provide a clearer, crisper image. The following two images, with their accompanying Histograms which show a graph of the distribution of shadows, midtones, and highlights from left to right, illustrate this.

In addition, maximizing the contrast ratio of an image aids further color correction operations by more evenly distributing that image’s color throughout the three tonal zones thatare adjusted with the three colorbalance controls in the Primary In, Secondaries, and Primary Out rooms. This makes it easier to perform individual corrections to the shadows, midtones, and highlights.

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For more information about adjusting image contrast, see Contrast Adjustment Explained.

Black

0% luminance

100%

109%

White

Super-white

Luma Explained

Luma (which technically speaking is gamma-corrected luminance) describes the exposure (lightness) of a video shot, from absolute black, through the distribution of gray tones, all the way up to the brightest white. Luma can be separated from the color of an image. In fact, if you desaturate an image completely, the grayscale image that remains is the luma.

Luma is measured by Color as a digital percentage from 0 to 100, where 0 represents absolute black and 100 represents absolute white. Color also supports super-white levels (levels from 101 to 109 percent) if they exist in your shot. While super-white video levels are not considered to be safe for broadcast, many cameras record video at these levels anyway.

Note: Unadjusted super-white levels will be clamped by the Broadcast Safe settings (if they’re turned on with their default settings), so that pixels in the image with luma above 100 percent will be set to 100 percent.

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What Is Setup?

People often confuse the black level of digital video with setup. Setup refers to the minimum black level assigned to specific analog video signals and is only an issue with analog video output to the Beta SP tape format. If you are outputting to an analog tape format using a third-party analog video interface, you should check the documentation that came with that video interface to determine how to configure the video interface for the North American standard for setup (7.5 IRE) or the Japanese standard (0 IRE). Most vendors of analog video interfaces include a software control panel that allows you to select which black level to use. Most vendors label this as “7.5 Setup” versus “0 Setup,” or in some cases “NTSC” versus “NTSC-J.”

Video sent digitally via SDI has no setup. The Y′C

video signals is 0 percent, 0 IRE, or 0 millivolts, depending on how you’re monitoring the signal.

minimum black level for all digital

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