Font Rendering in Windows 7

The world of display types is very complex and has a wide variety of users and their visual systems.  Microsoft did take much time into making Windows 7 ClearType the default rendering. This Cleartype Rendering technology was first launched with the Windows CE product in 2000. It was quite easy to check that ClearType worked properly on each device as the Windows CE environment is usually quite controlled in terms of the hardware used. So, you can either tune ClearType in Windows 7 language or adjust the hardware to change the Windows 7 onscreen reading experience. The very first launch of ClearType Rendering on the Windows operating system was with Windows XP in 2001.

Before the launch of Windows XP, Windows supported two types of font rendering. Bi-Level rendering and Font Smoothing/ Grayscale.

Bi-Level Rendering

The first type of font rendering was bi-level rendering which is mostly known as “black and white” rendering and also called aliased text. Bi-level rendering represents two colors in the font, the foreground color and the background color. When Windows 3.1 was released, this was the first type of rendering supported by TrueType and this was the necessary method of displaying fonts in bitmap form, especially when generated from outline technologies like TrueType which is very tough to change for low screen resolutions. It can take 6 months or a year for a skilled person to get this level of rendering detail. It can take even longer time if the character sets are larger.

 

Font Smoothing / Grayscale

The second form of rendering, known as font smoothing was first released as an option for Windows 95 in the Plus! Pack and it became the default rendering in Windows 2000 operating system. This technique is a hybrid grayscale anti-aliasing technique which is designed to enhance the contrast of fonts over the sequential anti-aliasing techniques. There are mainly two factors that separates font smoothing from more traditional text anti-aliasing.

The first traditional anti-aliasing technique works by overscaling the font outline data and then downsampling the data. The same technique is used by Font smoothing, but it applies the font hints prior to overscaling the outline data. Font hints often use a method know as ‘grid fitting’ to snap the vertical and horizontal edges of the font outline data so that the font outlines are aligned with the pixel grid. By doing this, most of the horizontal and vertical stems of a font outline cover 100% of the underlying pixels and they return the text foreground color when downsampled. This is usually black. Diagonal and round features of the font will return some shade of gray, reflecting the coverage of the underlying pixel as it will not have full coverage of the pixel and thus. Due to the higher contrast of the stems in the font at a slight cost of some spatial accuracy, this way of anti-aliasing is beneficial.