Digested on March 6, 2004Posted by David Earls
November 12, 2004: Typographer.org has been on a break for the last few months. New articles are in the pipeline and will be posted soon.
Designing graphics for television is what I do during daylight hours here in London. But television provides very specific challenges (and, of course, opportunities) for setting type. Designers are increasingly working across multiple media, and those coming from a print background especially may have a culture shock and need to learn some new rules. Hopefully, the following will help!
History explains all
Firstly, lets look at the technology, its history, and its inherent problems - feel free to skip this part if your eyes start glazing over by all means, but it relates directly to the advice given later, and gives the context of why the advice works.
Television is actually a pretty old technology, and many of the issues I deal with daily are as a result of that fact. The basic standards are PAL, NTSC and SECAM. SECAM was developed by the French in a political decision to protect its manufacturing base. Interestingly, many eastern block countries adopted SECAM for political motives - NTSC is an American system, and PAL was an improved derivative of it. What better way to delay cultural imperialism than using an incompatible television system? :) For our purposes, if you are designing for SECAM, treat it as PAL.
Why the different standards? Well, its all originally to do with electricity supplies - in most cases, you'll find NTSC used in countries with a 60Hz power supply, and PAL in those with a 50Hz power supply. It made things easier for the electrical engineers in a time when analogue was king - the power supply frequency was basically used as a clock, allowing the engineers to time when the next frame of video should be displayed.
As a result, we have different frame rates across the globe. PAL displays a higher resolution image (with superior colour) at 25fps (frames per second) and its lesser parent NTSC works at 30fps (well, 29.97 actually, since colour was introduced). What does differing frame rates across the world got to do with typography? This is all important, trust me.
So, why does a 60Hz screen create a 30fps image and not 60fps? Well, television screens are, for the most part, interlaced screens. That means that an image is made up of two passes, called fields. So for example, if an image is made up of, say, 20 lines, then it might be that firstly all the odd line numbers are show, then all the even numbers. This has two positive effects - field-based video and animations can take advantage of the slight time delay to make fast movement appear smoother to the eye, and secondly, a higher resolution image can be displayed on a low resolution screen, fooling the eye still further.
The downside is that certain types of image will flicker. Think about it - if you had a pattern made up of alternate white and black lines (like oh so many trendy websites in the 90s), then on a television, it would display as a frame of white, followed by a frame of black. This is why edges of high contrast can flicker (buzz or vibrate, as we like to call it in the industry) on screen.
Next up, safe guides. I am typing this on my boyfriend's iBook - its perfect LCD is sharp as nails from edge to edge, and I can see every single bit of the image. Televisions don't work in the same way, unfortunately. Firstly, there is the issue of overscanning. Televisions, to completely fill the screen no matter what, deliberately display images that go just beyond the edge of the visible screen. This is called overscanning (duh!) and needs to be taken into consideration for anyone working with television output. The area of the screen that is generally regarded to be safe for an image is called Action Safe - any critical action within a television signal that must be seen by the viewer is kept within this action safe area.
Next up, televisions, being clunky old CRTs, are not consistently sharp like LCD and other newer display technologies - at the edges, CRTs lose focus and definition. This is very important for typography as type that otherwise is perfectly readable on screen can blur into an unreadable nonsense. Therefore, within the action safe area, there is another, smaller area called Title Safe, where it is generally regarded to be safe from loss of focus.
We've talked about different resolutions, we've discussed interlacing and fields, and how different countries use different standards with different frame rates, along with overscanning and safe zones, but no word of type...
On with the type
1: Love it or hate it, all type on television should be anti-aliased, with no exceptions. If it is not, the contrast between the type and the backdrop will cause flickering due to interlacing.
2: Avoid fonts with thin horizontal lines - again, they will flicker like crazy on a television screen due to interlacing, even when anti-aliased and softened. Try and choose fonts that have at very least two pixels depth on any horizonal lines.
3: (Assuming a nominal resolution of 72pt) Dont use a font smaller than 18pt ever ever, and try and keep to above 21pt as much as possible. Besides the issues mentioned in points 1 and 2, remember the context in which television images are displayed. You are probably less than a metre (3 feet) from your computer monitor, but youíre likely to be quite a bit further away when watching Friends or Newsnight. The only possible exception to this is porn, of course.
4: Pick fonts with a large x-height - that will allow you to experiment with smaller sizes (below 28pt) but remain readable.
5: Donít use finely seriffed fonts - the serifs will break down on screen unless they're set very large indeed. Slab or wedge serifs are often good alternatives for television though - experiment, but always check on a broadcast monitor or television before committing.
6: If you are designing for a 16:9 ratio widescreen television, remember that the end design will be anamorphic (squished) and will lose some effective vertical resolution. Try not to choose overly thin, narrow typefaces as they may disintegrate at smaller sizes. Not the arena to be playing with movie poster fonts! While we are on the subject, if your widescreen design is shown on a 4:3 ratio normal television letterboxed (reduced in size so there is a black bar on the top and bottom, rather than having the sides cut off), bear in mind that type will be smaller and potentially less readable. You may want to compensate for this.
7: For static screens or overlays, Gaussian blur the end screen by "0.3" in Photoshop (or whatever you use): this will help with flickering by reducing the contrast between the background and the type.
8: Be careful of red type, especially if its highly saturated and for use on NTSC systems. It has a tendency to bleed. View your designs on a television or a broadcast monitor to be sure if you use red extensively in your designs.
9: This is where people may disagree with me: Be wary of very chunky (Impact springs to mind) fonts at smaller sizes, they can appear to fill in a little, much like print on newspaper, especially when you soften the type a little to cut back on flickering.
10: When animating type, experiment with frame blending and motion blur, which can give a smoother result. Be careful though, as it can hinder readability while in motion, especially below 36pt.
11: Where possible, recomposite animated type for the system you are using. For example, if you design for NTSC and need to reversion it for PAL (this happens a lot), the standards conversion process has to interpolate frames from about 30fps to 25, or indeed vice versa - this can cause a ghosting / after image effect from frame to frame. On typography, as it its inevitably high contrast, this can be very noticable. Secondly, because the resolutions used are different, a converted design will need to interpolate missing pixels - a small loss in quality. Its more work, for sure, but the results will be smoother and higher quality if you create two versions at the right frame rates and resolutions to begin with.
12: View your work! How it looks on your computer screen in your design or composition application will not match how it looks on television. Check it, ideally from a distance.
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