By Chris Blair
Have you ever noticed that graphics in low-budget television commercials and videos seem to almost scream at you? Much of that is from poor design, but another less conspicuous reason is how they’re created and superimposed on-screen. Poor graphic preparation can cause pixelated edges, dingy looking borders, over-saturated colors and color banding that can produce annoying noise on-screen.
In contrast, the graphics and text supers in well-produced videos seem to blend perfectly with the background video, displaying clean edges, soft contours and smooth color gradients.
Ever wondered why? The answer is twofold.
First, almost every video ends up being compressed for final playback. Compression works by throwing away information, which can play havoc with text and graphics. Second, creating clean graphics for television requires an understanding of how color and contrast works on-screen, as well as how keying and alpha channels work.
So let’s look at what compression does. Many compression schemes throw out 50% of the color information right off the bat! That’s right, 50% of the color is eliminated! Additionally, if your video is for broadcast, it’s up-linked and down linked and passed through and relayed and…well you get the idea. The bottom line is this can degrade quality. Of course television engineers will tell you that if it’s digital, the signal remains unchanged. But few delivery routes keep a video signal in it’s original form throughout the journey. So a video will likely be recompressed or converted to an analogue signal (and then back to digital) somewhere along its path. The result is a drop quality.
So how do you combat that loss? First, it helps to have good design and layout skills. Great design, coupled with good typestyle choices can make a huge difference in the look and feel of television graphics. But even well-designed graphics can suffer if the creator doesn’t follow a few guidelines to help fight the effects of compression.
First, pay attention to color. Televisions, even high definition units, have trouble properly displaying overly bright or heavily saturated colors. Reds and greens are particularly difficult to render correctly. It’s a good practice to keep the saturation level of graphics and text to no more than 80%. This helps colors look cleaner, bleed less around the edges and exhibit less noise when broadcast. It’s also absolutely required when using reds and greens. So NEVER use colors at 100% saturation.
Next is luminance or brightness. Keep your whites, yellows and other bright color values at 90% and under. You can get away with using 100% white if you’re using it as a pure background color, but if you’re superimposing white text against a dark background, using 100% white will make the edges appear harsh. In fact, we often keep white text closer to 80%. It still looks white on screen and the darker shade reduces contrast.
Of course you WANT contrast in most graphics, but the key is to reduce it just slightly. Reducing the contrast between background and foreground elements can soften their overall look and help the graphic appear cleaner. A good rule of thumb is to keep dark colors at 5-15% and bright colors at 80-90% of brightness values.
Also avoid using thin borders on text or foreground elements. If you have to use them, try to either soften them, thicken them slightly, or reduce the contrast between them and the main image. Remember, your video is almost certainly going to be compressed and resized, which is going to affect how your graphics render on-screen, and thin, contrasty lines suffer more than anything else during compression.
Another trick to getting cleaner, softer looking graphics is to not key them at 100%. We often key graphics at 90% or 95%, which also helps soften their look. The downside is that a little of the background image will show through, which can sometimes be distracting. But most of the time it’s imperceptible to viewers.
Next are color gradients, especially in large images or backgrounds. Televisions have a hard time rendering smooth gradients, especially when the video is compressed for delivery and playback. What that means is your smooth gradient is likely to end up looking like a series of bands. The solution? Don’t use symmetrical gradients, meaning a straight gradient from top to bottom or an oval one. Instead, use wavy curved lines for the gradient path, or better yet, take an image, make it black and white, add heavy blur, then overlay it with your background color in Photoshop. Play around with the blending mode until the gradient looks the way you want it.
Another trick is to add a slight amount of noise or grain. Usually a value of 1 in Photoshop is enough to eliminate the banding in your video. You can do the same thing to gradients in text or logos.
Lastly, there’s an art to creating clean key or alpha channels. If you aren’t familiar with key or alpha channels, they’re just an extra channel in a graphic or video that assigns transparency to certain areas based on grayscale value. White is usually opaque, and black is usually completely transparent, with all shades of gray in between having varying levels of transparency. The alpha channel determines which part of a graphic superimposes over the background.
Some file types are saved with completely transparent backgrounds, which makes keying them very easy. PNG and Photoshop files are two examples. Unfortunately, not all video editing applications play nice with those file types, and many animation programs prefer other file types, such as targa files (.tga). Targa files save the image with a color background, then use the alpha channel to determine what’s opaque or transparent when the graphic is keyed or overlayed. So with these types of files, the background color of your graphic influences how your keyed graphic looks on screen.
If you leave the background transparent in Photoshop, it will be white in your saved targa file. But if your text or graphic has black edges and your background is white, your edges will appear pixelated and jagged when the graphic is keyed. Why? Because creating smooth edges on graphics is really a hack. Graphics programs use decreasing levels of transparency along the edges to fool the eye into thinking the square, stair-step pixels that make up your graphic are curved and smooth. If the transparency along the edges of your black graphic let the white background show through, it ruins the effect, also ruining your clean key.
So what’s the solution? Making sure your background matches the color of the edges of your graphic. So if your graphic has dark edges, make your background color a similar color. If it has light edges, make it brighter. Of course, this can get dicey if you have graphics that have both dark and light edges. But don’t fret, there’s a solution for that too. Simply take your graphic layer, duplicate it, blur it slightly and then put it behind your original graphic. Create your alpha channel from the top graphic and voila! The slightly blurred graphic below the original helps to make the background edges the same color as the edges of the keyed graphic. If the key still isn’t clean enough, duplicate the background again and put two layers behind the main graphic. Do this until your key is clean.
This same principal works for motion graphics too. A perfect example is an organic element like fire. If you want to overlay animated fire over video in your timeline, you’ll have to save it with an alpha channel. Fire is mostly orange and yellow and to look realistic it needs varying levels of transparency around it’s edges. Plus, unlike a static graphic, it’s edges are constantly moving and changing. If you render your fire effect over a black background, then place that video (with alpha channel) in your timeline, the edges of your fire appear dingy and dark, which produces a wholly unconvincing effect. The black background is showing through where the alpha channel is only partially opaque.
The solution? Make the background of the fire animation orange or yellow. Now…the fire video will key cleanly because the edge transparency matches the color of the background. This principal can be applied to static graphics, web graphics, video, and even print graphics when using file formats that don’t support true background transparency.
The last tip to creating clean graphics and text is adding a slight amount of blur. We usually add a .2 gaussian blur to almost all graphics and motion graphic compositions. It smooths the edges just enough to make them look clean and soft, but doesn’t blur so much that the elements look out of focus.
So let’s review. If you want cleaner looking graphics:
- Reduce contrast and keep brightness values at 90% or under, and dark values at 10% or greater.
- Keep color saturation at 80% and under
- Make gradients asymmetrical and add a slight amount of noise
- Avoid thin borders, or try to soften them and reduce their contrast
- Set key levels at 90-95% instead of 100%
- Pay attention to background colors when creating alpha channels with certain graphic formats and video with alpha.
- Add a slight amount of blur to your final graphics and animation to soften their computer generated look.