Translating Print to Video
There's a natural expectation that graphics used in print will translate directly to broadcast television or presentation video. That's true if you know how to overcome the limitations of the video medium.
For artists, the first ghastly realization is the relatively horrible resolution available on standard video. Graphics intended for print typically require at least 300 dpi (dots per inch) or much higher on serious work. Television isn't measured in dpi because the display system could be virtually any size, so it doesn't apply. However, once the image is physically displayed, dpi can be measured for that particular instance. On a standard broadcast television display, you're lucky if you can achieve 50 dpi. That's right, about 50 dpi on a 19" display and even less as the display area gets larger. "Big Screen" TVs of the 1990's might achieve 20 dpi.
The reason for televisions's poor resolution is the number of available pixels in the video image. Compare this: an image of 300 dpi printed in landscape on U.S. Standard Letter paper would measure 3,450 pixels wide by 2,550 pixels tall. A standard television image is only 720 pixels wide and 486 pixels tall covering the same area which is a relatively crummy image - about 65 dpi. The compressed digital world (which is everything delivered to the consumer) has to live with only 480 vertical pixels.
Thinking in terms of consumer digital cameras which are typically 5 Megapixels (5,000,000 pixels), a standard television signal is only some fraction of that - less than 000.35 Megapixels (350,000 pixels). Sad but true.
High Definition television helps that problem a great deal. The current top end HDTV image is 1920 pixels wide and 1080 pixels tall. That's just north of a 2 Megapixel image but still far short of a common digital still camera. On a mid sized 42" HDTV screen (about 36" wide), that translates to - uhhh - 53 dpi. It's not much better than standard television on a 19" monitor and it seems we're right back where we started from. That's not quite true; there are more pixels in HDTV which allow the images to look great on bigger screens. Watching HDTV, suddenly you can read the street signs in the Rose Bowl parade where you couldn't before.
If you're dealing with a High Definition 720p image, that image is 0.9216 Megapixels (1280 wide by 720 tall) in the same image area - worse resolution than some cameras in cell phones but still very forgiving on larger screens.
The next realization is the limited color space available in video. The color gamut of video is tightly controlled due to the limitations of delivery systems. If you're used to designing with colors from Pantone charts, you can tear out the most vibrant of those from your swatch book. Dramatic colors like "Screaming Zonker Red" are outside of the range current digital systems may describe. It's possible to create a digital system to describe hugely saturated colors but the amount of data required to do that plus maintain subtle hue differences in the lower ranges would be prohibitive to record and transmit. Photoshop contains tools for use on art destined for video. You should get friendly with these tools because "legalizing" a picture for video will dumb your designs down if you press the limits.
Another rude shock is the non-square pixels of standard definition video. If you draw a circle in Photoshop, it will be an elipse on a standard definition video monitor unless you compensate for the differences. Standard Definition video has rectangular pixels that are stretched in width, so a circle in one medium is not a circle in another. Fortunately, the 1080 line and 720 line High Definition systems both have square pixels by design, so that's not an issue.
But wait, there's more. Designers can't use the whole canvas. There's a 20% bleed for titles or still graphic elements and a 10% bleed for action elements in the scene that move. Those margins are called "Title Safe" and "Action Safe" respectively. Both are caused by an old expectation that display devices are "overscanned". The need to compensate for overscanned displays is going away, but there should still be a healthy vertical and horizontal margin just for composition purposes.
If you're designing for HDTV, you may need to consider even more margin in the horizontal direction if the project will also be used in Standard Definition video. The sides of an HDTV product are simply cut off to reformat the images for SDTV, plus you need to allow for "Safe" areas on the remaining video real estate.
All this just scratches the surface of design limitations for video. As maddening as it is, designers need to throw away any expectation of highly detailed images, fine print elements or contrast that ranges from midnight to looking directly at the sun. That said, there are ways to achieve a perfectly viewable image on a video screen in either High Definition or Standard Definition.
Some basic rules of thumb for designing for video:
1. Save your images as 24 Bit RGB Color at 72 ppi (dpi).
2. Design your image file at 720x540 for NTSC graphics and resize down to 720x486 for final
output. (square to rectangular pixel adjustment)
3. Design your image file at 768x576 for PAL graphics and resize down to 720x576 for final
output. (square to rectangular pixel adjustment)
4. A pure white background will flicker on the television, and may cause text to flicker. Use an
light grey/off white (234,234,234) colored background.
5. Use maximum R, G, B values of 234 or less.
6. Run Photoshop's NTSC video filter on your graphic for it to bring colors back into "safe"
7. Action Safe is 90% of your screen size and is considered safe for elements other than text
that still needs to be seen.
8. Title Safe is 80% of your screen size and is considered safe for all text and elements that
"must" be seen.
9. Account for the Interlaced Scanning found in NTSC and PAL television sets. To avoid
flickering, make sure all fine lines are at least 2 pixels wide and that any width is defined in
multiples of 2 pixels.
10. 24 point fonts are best for television readability. A 14 point font, bold, is the absolute
minimum size to use.
11. Anti-alias all text to avoid sharp edges.
12. Leave around a 25 pixel border from the edge of the graphic so that any element doesn't
appear exactly at the edge of the screen.
13. Look at your work on a native video monitor (in addition to the computer display) to see
how it looks on a television used in someones home. What you see on your monitor will
most likely look better then what someone will have on their home TV.