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Smooth fonts in Microsoft Windows

Font smoothing was originally one of several system enhancements included in the Plus! pack for Windows 95. It continues to be a valid option for rendering text, but now shares the spotlight with ClearType. The article below was written many years ago and is provided for historic content. To learn more about the current state of font rendering on Windows read this new article about Windows 7.

Have you ever wondered why some characters look better than others when displayed on a computer screen? For example letters that are predominantly made up of vertical and horizontal lines such as the I, L, l, E, F and T look fine. However, those made up of diagonal and curved lines such as W, N, y, o and S look awkward and jagged. In his book Being Digital, Nicholas Negroponte describes these characters as looking like 'badly made Christmas ornaments'. Letters, like all images displayed on screen, are made up from square pixels. On most computer systems when it comes to text these pixels can be either on or off, black or white [see Figures 1 and 2].

Sample of text before font smoothing.
Figure 1. A sample passage of text rendered using 16 point Times New Roman before font smoothing has been activated.

Magnified detail of text before smoothing.
Figure 2. A detail of the passage (magnification x 2).

The 'Smooth Fonts' feature supported by Windows 95 with the Plus! pack simply uses intermediate colored pixels to smooth out the jagged diagonals and curves. This process is also known as 'anti-aliasing' or 'gray scaling.'

Sample of text after font smoothing.
Figure 3. The same passage of text rendered using 16 point Times New Roman, using smooth fonts.

Magnified detail of text after smoothing.
Figure 4. A detail of the passage (magnification x 2).

Only the problem areas of curves and diagonals are smoothed. The vertical and horizontal strokes are left intact.

The example shown in figures 3 and 4 use five different colors to create the smooth font effect - black, white and three levels of gray. However, the feature also works with any background and text color combination. Windows 95 decides which intermediate colors are needed for smoothing.

Smoothing is only applied to text above a specific type size which varies from font to font. Below this size the fonts 'hinting' information is used to optimise character appearance. This process is explained in our TrueType hinting document.

Font smoothing does not work in 16 or 256 color modes. The feature requires that Windows 95 is running in a HiColor (16bit) or better display modes.

The past

Anti-aliased text has long been used in multimedia titles and video games. Typically sections of text are created using graphics programs such as Adobe Illustrator or Corel Draw. These passages are then saved in a vector image graphic file format (such as Encapsulated PostScript) before being converted into a smooth anti-aliased bitmap picture using an application such as Adobe Photoshop.

This process is used in the production of the graphical logos and banners that we see on the Web. Once the text has been converted into a bitmap all manner of digital jiggery pokery can be applied to add texture, highlights and shadows. However, this process can be a repetitive and time consuming. Web commentator and type designer David Siegel claims that he spends more time anti-aliasing text than he does actually creating original content for his Web site. One of the main problems with the process is that once created bitmap text can be very difficult to edit. The designer is often forced to return to the original version of the text in order to make changes.

Although using bitmaps for anti-aliased banners, logos and icons can produce more than adequate results, when it comes to using them to display long passages of continuous text new problems arise. The huge size of the bitmap files makes them unsuitable for use on the Web. The smoothing process used by applications such as Photoshop often produces a more blurry looking image than that used by Windows 95. Figure 5 shows that when used to anti-alias small sizes of the Times New Roman font, Photoshop has trouble rendering fine detail such as serifs.

Figure 5. Times New Roman anti-aliased by Adobe Photoshop.
Figure 5. Times New Roman anti-aliased by Adobe Photoshop. Note how the vertical and horizontal strokes have been blurred and the serifs have virtually disappeared (magnification x 4).

Figure 6. The same word smoothed on the fly by Windows 95.
Figure 6. The same word smoothed on the fly by Windows 95. Each character is rendered individually so that vertical and horizontal strokes are left solid with smoothing only applied to curves, serifs and diagonal problem areas (magnification x 4).

Another problem associated with using bitmaps to display large sections of continuous text occurs when you want to print them out. By definition these graphics have been tuned for screen resolutions of between 72 and 96 dpi. When output at 300 or 600 dpi on a laser printer the results can be pretty poor. Because Windows 95 generates the on-screen smooth fonts from ordinary TrueType outlines, the output looks great on paper.

Additional information

Our TrueType in Windows 95 document contains a section dealing with the smooth fonts feature and how it works. Some common questions about the feature are also answered in our TrueType FAQ.

To learn more about recent developments in Windows font rendering technology, check out our ClearType page and also this article about Windows 7.

Last updated 24 June 2009.

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