T minus 9 days to ATypI Brighton 2007: Captioning

This one’s more for technical reference.

It is a pain in the arse to design typefaces for DVD subpictures for two reasons:

  1. You’re limited to one, two, or four colours, depending on how you read the spec, making it nearly impossible to include antialiasing.

  2. Your pixels are rectangular, not round or square, but they’re rectangles in four different aspect ratios depending on the TV broadcasting system and aspect ratio of the original.

    Aspect ratios, expressed as width:height
    Resolution Fullscreen, 4:3 Widescreen, 16:9
    NTSC: 720×480 pixels 0.909:1 (10/11) 1.212:1 (303/250)
    PAL: 720×576 pixels 1.091:1 (59/54) 1.455:1 (291/200)


  • All pixels are rectangular, making the task of drawing a circle difficult.
  • Current DVD subpictures look terrible because we’re using off-the-shelf fonts with rectangular pixels at ill-chosen pixel heights.
  • One way solve the problem while maintaining design consistency across all variants is to provide fonts of only certain pixel heights – preferably unit multiples of the native pixel dimensions. But that only works in the case of 720×480 4:3 resolution, where the 0.909 aspect ratio can be expressed as 10 pixels wide by 11 tall (10/11). The native pixel heights for the other variants are too large (250, 54, and 200 pixels).

The foregoing posting appeared on Joe Clark’s personal Weblog on 2007.09.03 14:00. This presentation was designed for printing and omits components that make sense only onscreen. (If you are seeing this on a screen, then the page stylesheet was not loaded or not loaded properly.) The permanent link is:

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