ClearType is a new rendering technology developed by Microsoft for an even better screen readability of TrueType fonts.
Originally, ClearType was conceived as a rendering technology for electronic books. Now, it is an option under Windows XP and potentially the next stndard renderer taking the place of the current black and white and/or greyscaling.
ClearType rendering works with all existing TrueType fonts. However, the co-called hints/instructions being part of most corporate TrueType fonts for better screen readability are interpreted differently from black and white or grey rendering. Thus, existing TrueType fonts not specially tuned for ClearType rendering, look less good when the ClearType option is switched on from Windows XP.
In order to achieve the best possible screen readability, the TrueType hinting has to be specially tuned for ClearType.
This might cause serious trouble since most of today’s corporate fonts are hinted to provide the best possible screen result in black and white or grey. ClearType ignores the tables that control when the fonts are displayed black and white respectively grey. URW++ has developed some corporate fonts for ClearType and knows how to optimize fonts for this new technology.
ClearType renders coloured glyphs that seem, at first glance, to look like well-rendered greyscaled characters. The calculation of coloured pixels in Red, Green, and Blue (RGB) gives better results by controlling every single colour pixel in RGB, compared to conventional anti aliasing. That’s why ClearType is perfectly suited for LCD screens where a single pixel consists of three horizontally arranged coloured pixels. The LCD technology provides a much better display of diagonals and curves in glyphs as well as a much better spacing by subpixel (RGB) positioning.