COLOR CORRECTION The digital filmmaking handbook
CHAPTER 15 COLOR CORRECTION white Note that this will change the contrast in your image, but altered contrast will probably be better than flat, solid highlights And, your highlights will now be legal for broadcast (Figure 15.10) Remember to reactivate the clamping in your CODEC before you continue F IGURE 15.10 With a simple Curves adjustment, you can manually “roll off” bright spots rather than clamping them Luma Clamping Troubles If you are using a CODEC that clamps luminance, you face another problem besides having your highlights reduced to flat blobs of white Say you have a 4-second clip and you need to crop the frame to a smaller size during the last seconds The easiest way to this would be to make a cut in the clip at the 2-second mark, and then apply a crop filter to the second part of the clip This cropping will cause your NLE to render new pixels for that clip, which of course, will require recompression using your chosen CODEC Unfortunately, if your CODEC performs luma clamping, the second clip will 355 DIGITAL FILMMAKING HANDBOOK 356 now have very different luminance values than the first clip Because the two clips are butted against each other, this change in luminance will be very obvious, and quite distracting What can you do? The best choice is to find a CODEC that lets you render unclamped video If this is not an option (either due to cost or availability), then you need to get the computer to re-render both clips (and possibly your entire movie) so that every clip will be subject to the same clamping If you apply a 1-pixel crop to each clip, then the computer will be forced to rerender everything Because your video is overscanned, you’ll never see this 1-pixel loss Correcting Color for Film If your project will eventually be transferred to film, color correction in the computer will be a bit of a problem If you’ve ever tried to print images on a color printer, you’ve probably discovered that what’s on your screen doesn’t al ways correspond to what comes out of your printer The same is true for transferring images to film The reasons for the disparity are many, and range from differences in color gamut between video and film, to differences in transfer processes, to differences in how the film is exposed during the transfer Professional editing and effects houses try to deal with this problem through expensive, complicated procedures for calibrating monitors and other digital equipment In the end, such systems still give little assurance of what the final color will look like If your final destination is film and you want to a lot of color correction and color effects, it’s a good idea to talk to your film transfer house Tell them you’re concerned about color control and ask their advice on how to proceed O NE M ORE T HING Finally, we recommend color-correcting your footage before you composite any other elements on top of it Your composited layers may have color issues of their own, so it’s better to separate the color troubles that your layers might have Once you’ve corrected each layer, you can composite them together and then apply touch-up corrections to smooth the “seams” of your composites If you’re not sure what we mean about composites, don’t worry, a thorough discussion of compositing is coming up next CHAPTER 16 Titling and Simple Compositing 357 DIGITAL FILMMAKING HANDBOOK 358 I N T HIS C HAPTER • • • • Making Titles in Your NLE Compositing with Keys What Is an Alpha Channel? Compositing with Mattes C ompositing is one of the most powerful effects tools available to the digital film-maker You’ll use compositing techniques for everything from repairing drop-outs, to creating video collages and special effects When we say “compositing,” we’re referring to the process of layering multiple images to create a final “composite” image The layers can be QuickTime movies or still images but, if you your compositing work well, your audience will simply see a single, well-integrated shot Your biggest concern when compositing will be to craft the mechanisms of transparency that will allow one image to be superimposed onto another Once your composite is built, you’ll need all of the color correction techniques we introduced in the last chapter to blend the layers into a seamless, cohesive image The simplest, most common compositing task is the creation of titles and credits Every movie needs opening titles and a final credit roll, and some movies—particularly documentaries—will probably need titles throughout The creation of titles marks the start of our compositing and special effects discussions, which will continue into Chapter 17 Titles and Simple Graphics Though your production may not need fancy special effects such as 3D-rendered dinosaurs, or complicated composites and morphs, it probably will need a title sequence at the beginning and a credit roll at the end If you’re shoot ing a documentary, you might also need to use titles to identify interviewees and locations Though your editing software probably includes some titling functions, they might not be up to creating a cool, animated title sequence, or even a simple list of rolling credits In this section we’ll cover the basics of titling and graphics and, along the way, introduce most of the concepts that you’ll need to understand to pull off the more complex, sophisticated effects that we’ll cover in the next chapter CHAPTER 16 TILTING AND SIMPLE COMPOSITING M AKING T ITLES IN Y OUR NLE Most editing packages include titling functions that let you superimpose simple text titles over your images Some packages include more advanced functions such as rolls and animated text Your editing package’s manual should cover everything you need to know to use the built-in titler But, no matter what software you use, there are several things to keep in mind when building your titles NOTE T IP Note that it is absolutely essential that you have an NTSC monitor hooked up to your system when you are creating titles! The only way to determine the legibility of your titles and graphics is to see them on an NTSC screen Titles for Film Projects If you’re finishing your project on film, the resolution of titles created in the internal title tool of your NLE will be too low for projection You’ll need to create high-resolution titles using Photoshop or After Effects and have them transfered directly to film You can also have titles created with an optical printer, which is how all film titles were created until recently The independent feature Boys Don’t Cry used optical printing for their titles and effects Safe Titles In Chapter 9, we discussed the action safe area of a shot As you’ll recall, to compensate for the possible differences between different television sets, a video signal actually contains more picture than can be displayed Your TV or video monitor will crop off a good amount of this overscanned area Because it’s impossible to determine how much a particular TV or monitor will overscan, some lowest-common-denominator averages have been determined If you stay inside these averages, the odds are pretty good that your video will not be cropped outside the edge of the monitor The action safe area is the larger of the two regions, while the title safe area is a little smaller Keep your titles within this area and they should be viewable on any screen Most titling functions allow you to display both action and title safe guides If your editing package doesn’t provide guides, then try to avoid placing text in the outer 5% or so of your screen (Figure 16.1) 359 DIGITAL FILMMAKING HANDBOOK 360 F IGURE 16.1 If you want to be sure your titles aren’t cropped by the viewer’s monitor, be sure to keep them within the “Title Safe” area Safe Colors NTSC and PAL video have much smaller color gamuts than your computer monitor This means that colors that look fine on your computer screen may not display correctly—in fact, they might look plain awful—when displayed on an NTSC monitor Very saturated colors will tend to bleed and fringe, with reds suffering the most (Color Plate and Figure 12.12 show good examples of oversaturated red created in an internal titler.) Unfortunately, the titling functions of most editing programs will let you choose colors that are not NTSC “legal.” This means you may have to some experimentation to find colors that are safe for NTSC display The easiest way to determine if a color is safe is to simply look at it on an NTSC monitor or a vectorscope Both After Effects and Photoshop provide a Broadcast Colors filter that will convert your graphics to NTSC-safe colors These tools make it easier to reduce a color to something legal When choosing colors, also pay attention to what will be behind your titles If you’re superimposing titles over video, be sure that the colors you pick are CHAPTER 16 TILTING AND SIMPLE COMPOSITING visible throughout the entire clip Though a blue title might look great at the beginning of a clip, make sure there are no blue, title-obscuring objects moving through the frame later in the clip For better visibility, consider adding a slight drop-shadow or outline to your text (Figure 16.2) Title Titles Like everything else related to filmmaking, there’s a whole mess of terms related to titling Whether you use these terms or not is up to you Title Card A non-moving title Head Credits The typical series of title cards that fade in and out at the beginning of a movie Typically, head credits follow (roughly) this order: studio, sometimes a producer, title, lead actors, casting, music, music supervisor, costumes and makeup, designer, director of photography, executive producer, producer, writer, director Tail Credits (or End Credits) The credits at the end of a movie Title Roll A long list of titles that scrolls from the bottom of the screen to the top Usually used for End Credits A very efficient way of presenting titles, as every name is on-screen for the same duration Title Crawl A line of titles that moves horizontally across the screen, usually at the bottom Supered Titles that are superimposed over other video Lower Thirds Titles that fit into the lower-third of the frame Usually credits identifying a speaker, such as you might use in a documentary Pad A colored background or stripe behind a lower third title Pads improve a title’s legibility Textless version A print of your feature with no titles Sometimes necessary for foreign distribution Choosing Your Typeface and Size Remember that NTSC video is lower resolution and much less sharp than the video on your computer screen Typefaces with fine lines and swirly details may not read very well on-screen When superimposing titles over video, make sure that the typeface you choose is readable throughout the clip Fast-moving images with lots of clutter will make smaller, finer-lined typefaces more difficult to read 361 DIGITAL FILMMAKING HANDBOOK 362 When choosing a type size, legibility should be your first concern At small sizes, some typefaces will be more legible than others, but in general, anything below 20 points will be too small (Figure 16.2) Ordering Your Titles If you’re working with union actors, their contract may specify where their name must appear in the title sequence Similarly, credit position may have been stipulated from a “producer” when you talked him or her out of some funding Be sure to consider all of these agreements and obligations when ordering and creating your titles TIP Start with a Word Processor If you have a long list of titles, such as lower thirds for a feature-length documentary, subtitles for an entire film (or even just a scene or two), or a long credit list, use a word processing program to create the list of titles and be sure they are proofread and error-free before you start creating graphic titles You can easily cut and paste them into your cg titler and save hours spent typing and fixing mistakes F IGURE 16.2 Be sure to consider both legibility and composition when creating titles CHAPTER 16 TILTING AND SIMPLE COMPOSITING Placing Your Titles If you’re planning on superimposing your titles over video, you’ll want to give some thought to their placement, not just for the sake of readability, but for good composition as well Hopefully, you shot the underlying videos with titles in mind Though titles may sit on top of an image, they should not be thought of as separate Be sure to consider the composition of the whole image—titles and video—when placing your graphics If your titles are going to move about the screen, make sure they are readable across any and all action over which they are superimposed Legible titles don’t really any good if the viewer doesn’t have time to read them A good rule of thumb is to leave the title up long enough for you to read it two times aloud Usually this means at least four seconds for a fairly short title, not including fades in or out Even if you read fast, the title will probably be up long enough for most people to read it In general, pay close attention to the pacing of your head title sequence Remember: This is the beginning of your presentation and is a chance for you to set an initial tone for your story If you have already presented a “prelude” before the credits, your title sequence can function as a dramatic beat to prolong what has come before Though you don’t want to bore the audience with a long title sequence, if the beginning of your story is somewhat slow and somber, a slower title sequence might be just the thing to slow your audience down to a more receptive pace Titles can serve as another beat in your storytelling process, so give them some thought Learning from Other People’s Titles Next time you’re at the movies, consider how the director has used the title sequence Many action movies, for example, skip titles all together and cut right “to the chase,” so to speak James Bond movies are famous for their elaborate title sequences that occur after an initial high-energy sequence These sequences serve to bring the audience down from the chase-scene high to the typically more sedate “first” scene Some movies choose to superimpose their titles over initial, expository action Be careful with this technique, though You don’t want to distract the audience from your exposition, and you don’t want to give short shrift to your titles At the opposite extreme from these approaches are the title sequences used by Woody Allen in most of his movies Simple slates on a black back- 363 364 DIGITAL FILMMAKING HANDBOOK ground, these titles sequences are completely separate from the “main” presentation Though you may think we’re making rather a big deal out of something that can be very simple, don’t forget that every frame that you show the audience can—and usually does—carry some sort of information about your story Consequently, it’s worth the time to make sure you’re using your title sequence as well as you can C REATING T ITLES IN P HOTOSHOP If your editing package doesn’t include a titler, or if you want to create fancier titles than what your editing app can create, you can always craft titles in a paint program or image editor After you’ve created your title images, you can take them into your editing or special effects package and composite them with your video or other graphics In the next section, we’ll cover everything you need to know to perform simple composites Compositing 101 In theory, compositing sounds like a very basic effect: put one layer of video on top of another to create a composite In practice, though, compositing is one of the most powerful tools at your disposal At the simplest level, you can use compositing tools to superimpose custom titles and graphics over your video, or stack clips on top of each other to create a video collage More sophisticated compositing tools allow you to everything from mixing computer-generated elements with live video, to placing your actors inside virtual sets Though good compositing tools are the foundation of all special effects work, they can also be used for more everyday concerns such as fixing dropouts and altering the color of an image In most non-linear editing packages, you can create a simple composite by creating multiple video tracks, each with a different clip, and all stacked on top of each other (Figure 16.3) Dedicated compositing programs such as Adobe After Effects provide more compositing power by letting you stack many layers of video and stills In addition, After Effects lets you nest one composition inside another to ease project management After Effects also lets you animate the properties of layers to create sophisticated, animated effects No matter which program you use, the process of compositing is fairly simple First, you import your video clips and stack them up in the appropriate ... down the bullet hole to something more appropriate, then position the hole somewhere on the door In After Effects, we can 373 DIGITAL FILMMAKING HANDBOOK 374 A B F IGURE 16.10 By feathering the. .. stay inside these averages, the odds are pretty good that your video will not be cropped outside the edge of the monitor The action safe area is the larger of the two regions, while the title safe... places in the clip where the hand recoils This is a good way to zero in on the flash S TEP 3: P OSITION THE FLASH IN THE TIMELINE In the timeline, scrub through your footage and watch the program