By Steven J. Cohen and Steven Ramirez

Since I started contributing tips to the Editors Guild Magazine, I have received several e-mails from members asking how to prepare graphics for use in editing and compositing systems. What is the best graphics application to use? The best file format? What are alpha channels, and how does one save them correctly? As I was pondering how to address these questions, Adobe announced the release of its new versions of Photoshop and Illustrator, called “Creative Suite” or “CS” for short. The timing couldn’t have been better, because these new versions contain features specifically for video. In this article, I’ll go through the fundamentals of creating graphics, and I’ll also cover some new Creative Suite features.

Figure 1. The Layer Style window in Photoshop offers many ways to dress up text elements. Access it by double-clicking on the layer in the Layers palette.

Choosing an Application

Before you decide which application to use to create text elements, you need to determine what type of graphics file is most appropriate for the task at hand. There are two ways that images and text are represented digitally: as “raster” graphics and as “vector “ graphics.
Raster graphics (also known as bitmaps) are composed of pixels, or picture elements, where each pixel represents a color value. If you zoom in on a raster graphic, or scale it up much past 100 percent, you’ll see the individual pixels, which is not generally something you want. For this reason we say that raster graphics are “resolution dependent” and have a set size in terms of pixels. JPEG, TIFF, Targa and BMP are all raster graphics file formats.

Vector graphics, on the other hand, are composed of outline shapes and fill values, instead of pixels. For this reason, vectors can be scaled to any size and still look clear and have sharp edges. Because of their scalability, we say that vector graphics are “resolution independent.” While this outline-and-fill scheme isn’t very good for describing images with lots of gradients (a photo of someone’s face, for example), it is excellent for preparing text and illustrations that have a relatively simple color palette. EPS and Illustrator (AI) are vector file formats.

A general rule of thumb is if you’re creating something photographic, use Photoshop. If it’s typographic or illustrative (like a simple logo), ask yourself how large the graphic needs to be. If it has to be big (for example, if it will zoom towards the camera), your best choice is Illustrator. If the graphic does not need to scale up much past 100 percent, then Photoshop is probably better.

Setting Up a Photoshop Document

When creating a new document in Photoshop, choose a resolution that matches or is larger than the size of the image in your editing or compositing system. This gives you the ability to change the size of your text or graphics without sacrificing quality, because it’s always better to scale down a large image than scale up a small one.

To make a new document in Photoshop, choose File>New. In Photoshop 7 and later, the New Document window includes a pop-up menu with presets for many standard video resolutions. If you are making graphics for an Avid project using footage digitized from standard-definition video, and you are working in Photoshop 7 or earlier, set your resolution to 720x540 (or larger). This may seem surprising, given that the resolution in your Avid is 720x486, but this is necessary to maintain the proper proportions when the titles are imported into your Avid. Computer screens have square pixels, but video formats use rectangular pixels, which means that if you use the same resolution for Photoshop that you’re using in your editing program, the graphics will appear elongated from top to bottom when you import them into your project. (The settings are slightly different if you are working in DV — the Photoshop file resolution should be set to at least 720x536, because the resolution of DV is 720x480.)

Figure 2. To save a Photoshop image with its alpha channel, choose File>Save As. Select either Photoshop, PICT, Targa or TIFF from the format pop-up and make sure the Alpha Channels box is checked.

This is not the case in PhotoShop CS, however. The program has a new “pixel aspect ratio correction” feature that makes it possible to work with rectangular pixels in Photoshop, but display them without distortion on your computer’s square pixel monitor. When creating a new document, specify pixel aspect ratio by clicking on the Advanced button in the set-up window to reveal the Pixel Aspect Ratio pop-up menu. Choose the pixel aspect ratio that matches your editing project — generally D1/DV NTSC (0.9). The New Document preset for D1 will then create a canvas the size of 720x486, but it will be displayed correctly on your square-pixel computer monitor. (This setting can be toggled on and off by selecting it from the View menu.)

There is one more important setting in the New Document window. To make your image transparent, so that it can be superimposed over your video footage with the background showing through, under Contents click the Transparent option, rather than White or Background Color.

Setting Up An Illustrator Document

In Illustrator, the New Document window also contains a pop-up menu with frame sizes, although there are fewer than in Photoshop. Because Illustrator files are resolution independent and can be scaled up, you do not need as many choices. The important issue is the aspect ratio of the image, and for video work, either 640x480 or 800x600 will work fine. In the New Document set-up, you’ll also need to change the Color Mode and Units settings. Illustrator is designed primarily for print work, so its default color space is CMYK, and its default units are points. For video work, change these to RGB and pixels respectively
Because video is a pixel-based medium, vector graphics intended for video will eventually have to be rasterized, or converted to bitmaps. Most compositing programs and some editing programs rasterize files when they are first imported into the program. I advise editors who want to bring Illustrator files into their Avid to first rasterize them in Photoshop. Drag the Illustrator file onto the Photoshop icon (or in Photoshop, choose File>Open and select the Illustrator file). You will be presented with the Rasterize dialog box. Choose your resolution, just as you would for any other Photoshop document, then save the file in an appropriate bitmap format for import into your editing system.

Enhancing Text Elements

Once you have set up your Photoshop or Illustrator document, you can type in any color text you want using the Text tool, then apply effects to it. In Photoshop, if you double-click on your text layer in the Layers palette, you will open the Layer Style window, where you can find options like Drop Shadow, Bevel and Emboss, Inner and Outer Glow and more (Figure 1). The styles are listed on the left of the window and can be turned on and off by checking the box next to them; clicking on a style’s name will open a control window where you can change its parameters. Additional effects can be found under the Filter menu. To apply effects in Illustrator, select your text by clicking on it with the Selection Tool (the black arrow), then go into the Filter and Effect menus and experiment.

File Formats and Alpha Channels

Once you’ve created your Photoshop or Illustrator graphics, you will need to bring them into your editing or compositing system.

Begin by saving them in the native Photoshop or Illustrator file format. This will enable you to revise them and work with individual layers if necessary. Moreover, many applications, including Avid, Final Cut Pro, After Effects and Combustion, support layered Photoshop files, so you can import and work with the master Photoshop file and all of its layers. When you import a Photoshop file this way, its transparency will automatically be preserved, so that your underlying footage will show through.

However, you may not want to bother with all those layers in your editing application. If that’s the case, keep your original master with all its layers, but save a flattened copy. You can do this as a Photoshop file, or you can use a more universal format, such as Targa, TIFF or PICT.

When you do, you will need to create an alpha channel to preserve the transparency information of the file so that you can composite it over your video image. An alpha channel is a grayscale image that records levels of transparency — the darker the value, the more transparent that portion of the image. It is not a layer, but a channel, like the red, green and blue channels that give your image its color. If there’s one present in a Photoshop file, it can be seen in the Channels palette, which is usually grouped with the Layers palette. To create an alpha channel in Photoshop, first select all the transparent areas of an image, then turn that selection into your new alpha channel:

1.		Make sure that the checkerboard background is visible in the areas of your image meant to be transparent. If it isn’t, check that you don’t have any solid background layers turned on.
2.		Choose “Merge Visible” from the Layers palette pop-up menu (top right corner of the palette). Throw away any unused layers so you’ve only got one layer in the Layers palette.
3.		From the Select menu, choose Load Selection. In the Channel pop-up window, it will say “(name of your layer) transparency.” Click OK. A flashing dotted line will appear around the transparent areas of the image, showing that those have been selected.
4.		Go back to the Select menu and choose Save Selection to create a new channel. It will say “new” in the channel pop-up. You can name this channel if you’d like, but it is not necessary. Click OK.
5.		Click on the tab for the Channels palette. (If it’s not grouped with your Layers palette, choose Channels from the Window menu.) You should have five channels: RGB, red, green, blue and alpha.

Figure 3. These are the Avid import settings for Photoshop images created at 720x480 or 720x486 resolution, using D1/DV rectangular pixels. If your image was created with square pixels, set Aspect Ratio, Pixel Aspect to "Maintain, Square."

To save the image with its alpha channel, choose File>Save As. Select either Photoshop, PICT, Targa or TIFF from the format pop-up and make sure the Alpha Channel box is checked (Figure 2). Click OK. (In Photoshop 7, there is a glitch in saving some of these file formats; you may not be able to click in the Alpha Channels box unless you flatten the image before you save it, then unclick the Save a Copy option in the Save As dialog box.) Close the original document without saving to preserve your multi-layer master version.

Bringing Graphics into an Avid

When you import graphics into your Avid, you will be faced with a number of options (Figure 3). If your Photoshop document was set to a 720x480 or 720x486 resolution, with D1/DV rectangular pixels, choose the following settings in the Import dialog box:

Aspect Ratio, Pixel Aspect: 601, non-square.
Color Levels: RGB
Alpha: Invert Existing

For a document with a 720x540 resolution (or any other resolution that uses square pixels), choose “Maintain, Square” for the Aspect Ratio, Pixel Aspect setting, and keep everything else the same.

The disadvantage to creating graphics outside of your editing application is that after you import them, you will only be able to make limited changes to them without going back into the program that created them. If you import an image that has been “flattened,” or collapsed into a single layer, then you can do little more than reposition it on screen and make it smaller. If you are using an editing or compositing application that can support layered Photoshop files, then you’ll have control over the separate layers, but you still won’t be able to change the content of the image without going back to Photoshop.

Wrap Up

Creating titles and other elements in Photoshop and Illustrator makes it possible to do much more sophisticated text handling, better drop shadows and all kinds of text effects that the Avid and other editing systems cannot provide. This article describes the basics, but only hints at the complex work that you can do in these programs. If you haven’t already, you might consider taking a Photoshop class like the one I teach at Glendale Community College, where you can learn more about using Photoshop and Illustrator CS in conjunction with your editing or compositing software.