The ClearType Font

Caution: Techie terms ahead

What is ClearType

ClearType is a technology of showing text in a font. ClearType is owned by Microsoft and was introduced first in 2000.

How it Works

Normally, the software in a computer treats the computer’s display screen as a rectangular array of square, indivisible pixels, each of which has an intensity and color that are determined by the blending of three primary colors: red, green, and blue. However, actual display hardware usually implements each pixel as a group of three adjacent, independent subpixels, each of which displays a different primary color. Thus, on a real computer display, each pixel is actually composed of separate red, green, and blue subpixels. 

If the computer controlling the display knows the exact position and color of all the subpixels on the screen, it can take advantage of this to improve the apparent resolution in certain situations. If each pixel on the display actually contains three rectangular subpixels of red, green, and blue, in that fixed order, then things on the screen that are smaller than one full pixel in size can be rendered by lighting only one or two of the subpixels. For example, if a diagonal line with a width smaller than a full pixel must be rendered, then this can be done by lighting only the subpixels that the line actually touches. If the line passes through the leftmost portion of the pixel, only the red subpixel is lit; if it passes through the rightmost portion of the pixel, only the blue subpixel is lit. This effectively triples the horizontal resolution of the image at normal viewing distances; the drawback is that the line thus drawn will show color fringes (at some points it might look green, at other points it might look red or blue).

ClearType uses this method to improve the smoothness of text. When the elements of a type character are smaller than a full pixel, ClearType lights only the appropriate subpixels of each full pixel in order to more closely follow the outlines of that character. Text rendered with ClearType looks “smoother” than text rendered without it, provided that the pixel layout of the display screen exactly matches what ClearType expects.

Why Are We Bothered 

Microsoft had implemented ClearType font in all MS Office products from 2007 and onwards. This is on by default. If at all you feel your font is rendered bit blurry, you may want to try switching off this feature.

According to a study at the University of Texas, ClearType "may not be universally beneficial". The study notes that maximum benefit may be seen when the information worker is spending large proportions of their time reading text (which is not necessarily the case for the majority of computer users today). Additionally, over one third of the study participants experienced some disadvantage when using ClearType. Whether ClearType, or other rendering, should be used is very subjective and it must be the choice of the individual, with the report recommending "to allow users to disable [ClearType] if they find it produces effects other than improved performance".

How to Disable / Enable ClearType 

Excel 2007:

Click the Microsoft Office button > Excel Options > Popular tab > Top options for working with Excel segment > clear the Always Use ClearType check box.

Excel 2010 and later:

File tab > Options > General > User Interface options segment > clear the Always Use ClearType check box.

Follow the same steps but check the box if you want to enable this feature.

Points to Remember

You will have to close all the Office applications that are open while changing this feature to take effect. 

Microsoft do not recommend to turn off this feature. As a workaround, you can use Microsoft’s ClearType tuning tool. More information can be found here.