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In situations like these, you’ll want to preview how colors will appear when they’re displayed on a device other than your computer monitor. Output simulation requires display color management.
During output simulation, colors are converted from the project’s working color space to the monitor’s color space
through the following flow:
1. Colors are converted from project’s working color space to output color space. Colors are converted from the working color space to the color space of the output type using the output color profile (the same profile that will be used for rendering to final output).
2. Colors are converted from output color space to simulated playback device’s color space. If Preserve RGB is not selected, colors are converted from the output color space to the color space of the presentation medium using the simulation profile. This presumes that the simulated device also performs color management and will convert colors for display. Color appearance is preserved; RGB numbers are not preserved.
If Preserve RGB is selected, the color values are not converted in this step. Instead, the numerical RGB color values are preserved and are re-interpreted to be in the color space of the simulated device. One use of this simulation is to see how a movie will look when played back on a device other than the one for which it was intended or a device that does not perform color management.
Note: Preserve RGB is also used when simulating the combination of a capture film stock and a print film stock.
3. Colors are converted from simulated playback device’s color space to your monitor’s color space Colors are converted from the presentation device color space to the color space of your computer monitor using the monitor profile.
When you create an output simulation preset, you can choose a profile to use for each of these steps.
Even if you’re using a preset output simulation, you can choose the Custom option in the View Simulate Output menu after selecting the preset to see a representation of which color conversions and reinterpretations are occurring for that simulation type.
Output simulation applies only to a specific viewer (Composition, Layer, or Footage panel) and works only for previews. Color conversions for output simulation are performed when values are sent to the display. Actual color numbers in the project are not changed.
As with all color space conversions, simulating output decreases performance somewhat, so you may not want to simulate output when performing tasks that require real-time interaction.
AFTER EFFECTS CS3 249 User Guide Note: Merely applying the correct profiles can’t compensate for different color gamuts for different devices. For example, common LCD monitors do not have the gamut necessary to fully simulate HDTV output.
You can press Shift+/ (on the numeric keypad) to turn display color management on or off. Turning display color management off also turns output simulation off. Simulation settings (including No Output Simulation) are remembered.
See also“Previewing” on page 120“Color Profile Converter effect” on page 543
Simulate output for previews 1 Activate a Composition, Layer, or Footage panel.
2 Choose View Simulate Output, and choose an output type to simulate.
Note: Output simulation relies on display color management, which is on by default. If display color management is off, choose View Use Display Color Management.
No Output Simulation Display color management is on, but no conversion is performed to simulate an output type.
Macintosh RGB Show how colors will appear when displayed by a non–color managed application on a Macintosh computer (with a gamma of 1.8). This option is not available if Linearize Working Space is selected.
Windows RGB Show how colors will appear when displayed by a non–color managed application on Windows (with a gamma of 2.2). This option is not available if Linearize Working Space is selected.
Kodak 5218 To Kodak 2383 Show how colors will appear when output to the Kodak 5218 negative film stock and then projected from Kodak 2383 positive film stock in a theater environment.
Note: The DPX Theater Preview and DPX Standard Camera profiles provided by After Effects 7.0 for use with the Proof Colors command have been replaced by the Kodak 2383 and Kodak 5218 profiles used with the Simulate Output command.
Custom If you don’t see an entry for the output type that you want to simulate, you can create your own output simulation preset by choosing Custom. You can specify a profile to use for each of the conversion or reinterpretation steps.
• To preview how a movie will look if you output the movie to a device and view it on that device, use the same value for Output Profile and Simulation Profile.
• To preview how a movie will look if you output the movie to one device and then view it on another, colormanaged device, use different values for Output Profile and Simulation Profile, and deselect Preserve RGB.
• To preview how a movie will look if you output the movie to one device and view it on another device, use different values for Output Profile and Simulation Profile, and select Preserve RGB.
You can choose an output simulation preset for each view. Custom output simulation settings are shared between all views.
AFTER EFFECTS CS3 250 User Guide Simulate an output type in a movie rendered for final output Color management for output simulation is only for previews, but you can render a movie with a look that simulates a particular output type. For example, you can render a movie for HDTV that simulates a film appearance. This is especially useful for creating dailies when doing film work.
1 Choose Layer New Adjustment Layer to create a new adjustment layer at the top of your composition.
2 Choose Effect Utility Color Profile Converter to apply the Color Profile Converter to the adjustment layer.
3 Choose Edit Duplicate to duplicate the effect.
4 In the Effect Controls panel, set the following options for the first instance of the effect:
Input Profile Project Working Space Output Profile The type of output to simulate; for example, a film printing density profile, such as Kodak 5218/7218 Printing Density Intent Absolute Colorimetric 5 In the Effect Controls panel, set the following options for the second instance of the effect:
Input Profile The type of playback to simulate; for example, a theater preview profile Output Profile The color space of the output medium; for example HDTV (Rec. 709) Intent Relative Colorimetric To enable and disable this kind of output simulation, you can turn the adjustment layer on and off by selecting and deselecting its Video switch in the Timeline panel.
Broadcast-safe colors Analog video signal amplitude is expressed in IRE units (or volts in PAL video). Values between 7.5 and 100 IRE units are considered broadcast-safe; colors in this range do not cause undesired artifacts such as audio noise and color smearing. (In practice, some spikes over 100 IRE are legal, but for simplicity 100 IRE is considered the legal maximum here.) This range of 7.5-100 IRE is equivalent to a range from black to white of 64-940 in 10-bpc values for Y' in Y'CbCr, which corresponds to 16-235 in 8-bpc values. Therefore, many common video devices and software systems interpret 16 as black and 235 as white, instead of 0 and 255. These numbers don’t directly correspond to RGB values.
If you notice that colors of imported footage look wrong—blacks don’t look black enough, and whites don’t look white enough—make sure that you’ve assigned the correct input color profile. The common video color profiles included with After Effects include variants that account for these limited ranges, such as the HDTV (Rec. 709) 16color profile, which interprets 16 as black and 235 as white.
Note: Some video cards and encoders assume that output is in the range 0-255, so limiting colors in your composition and rendered movie may be redundant and lead to an undesired compression of the color range. If colors of your output movie look dull, try assigning an output color profile that uses the full range of colors.
You can use the Broadcast Colors effect to reduce luminance or saturation to a safe level, but the best way to limit output colors to the broadcast-safe range is to create your composition to not use colors out of this range. Keep the
following guidelines in mind:
• Avoid pure black and pure white values.
• Avoid using highly saturated colors.
• Render a test movie and play it on a video monitor to ensure that colors are represented accurately.
AFTER EFFECTS CS3 251 User Guide The Color Finesse plug-in included with After Effects includes excellent tools that can help you keep your colors within the broadcast-safe range. For more information, see the Color Finesse documentation in the folder containing the Color Finesse plug-in.
Note: After Effects 7.0 had an Expand ITU-R 601 Luma Levels option in the Interpret Footage dialog box. When opened in After Effects CS3 or later, footage items in projects created with this option will have a corresponding assigned profile.
Working with Cineon footage items A common part of the motion-picture film production workflow is scanning the film and encoding the frames into the Cineon file format. The DPX (Digital Picture Exchange) format is a standard format closely related to the Cineon format.
Cineon data is stored in a logarithmic format, with each color channel taking up 10 bits.
Stu Maschwitz has a blog post that goes into some of the finer details of what it means to say that Cineon files' color values are in a logarithmic color space: www.adobe.com/go/learn_ae_stucineonlog.
Cineon data has a 10-bit white point of 685 and a 10-bit black point of 95. Values above 685 are retained, but are treated as highlights. Rather than abruptly clipping highlights to white, After Effects interprets highlights using a gradual ramp defined by the Highlight Rolloff value. You can modify the 10-bit white point and 10-bit black point input levels and the output (converted) white point and black point levels to match your specific footage items or creative needs.
Use a project color depth of 32 bpc when working with Cineon footage items so that highlights are preserved, in which case you don’t need to roll off the highlights.
There are three basic ways of working with Cineon footage items in After Effects:
• The easiest—and recommended—way is to enable color management and assign an input color profile to a Cineon footage item in the Color Management tab of the Interpret Footage dialog box, corresponding to the film stock on which the footage was recorded. Of course, if creating output for film, you should use the same profile as the output color profile so that the output file matches the film stock. One advantage of using color management features to work with Cineon footage items is that compositing with images from other footage types is made easier. See “Interpret a footage item by assigning an input color profile” on page 245.
• If you need to manually modify the settings for a Cineon footage item, or if you don’t want to use color management, then you can use the Cineon Settings dialog box. To open this dialog box, click the Cineon Settings button in the Color Management tab of the Interpret Footage dialog box.
• If you need the settings for the interpretation of the Cineon footage item to change over time, then you can apply the Cineon Converter effect to a layer that uses the Cineon footage item as its source.
See also “Cineon Converter effect” on page 542 Chapter 10: Masks, transparency, and keying Transparency overview Use masks, keying effects, and mattes to determine which parts of a layer are transparent, allowing other layers to show through.
About transparency Before you can create a composite from multiple images, parts of one or more of the images must be transparent. You can use alpha channels, masks, mattes, or keying to define which parts of an image are transparent and which parts of an image can be used to obscure parts of another image. By manipulating transparency and choosing blending modes, you can create a variety of visual effects.
About alpha channels and mattes Color information is contained in three channels: red, green, and blue. In addition, an image can include an invisible fourth channel, called an alpha channel, that contains transparency information.
A matte is a layer (or any of its channels) that defines the transparent areas of that layer or another layer. White defines opaque areas, and black defines transparent areas. An alpha channel is often used as a matte, but you can use a matte other than the alpha channel if you have a channel or layer that defines the desired area of transparency better than the alpha channel does, or in cases where the source image doesn’t include an alpha channel.
Many file formats can include an alpha channel, including Adobe Photoshop, ElectricImage, Adobe Flash Video (FLV), TGA, TIFF, EPS, PDF, and Adobe Illustrator. AVI and QuickTime (saved at a bit depth of Millions Of Colors+), also can contain alpha channels, depending upon the codecs used to generate these file types. For Adobe Illustrator EPS and PDF files, After Effects automatically converts empty areas to an alpha channel.
About straight and premultiplied channels Alpha channels store transparency information in files in one of two ways: straight or premultiplied. Although the alpha channels are the same, the color channels differ.
With straight (or unmatted) channels, transparency information is stored only in the alpha channel, not in any of the visible color channels. With straight channels, the effects of transparency aren’t visible until the image is displayed in an application that supports straight channels.
With premultiplied (or matted) channels, transparency information is stored in the alpha channel and also in the visible RGB channels, which are multiplied with a background color. The colors of semitransparent areas, such as feathered edges, are shifted toward the background color in proportion to their degree of transparency.