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Cleartype is great when displaying small text (say 10-16px).

However when you display something above 20px it starts looking like mud.

Just compare it to Photoshop. Photoshop rendering at small size is not very impressive, too blurry. But if you compare it at 20px, Photoshop wins all the time. Cleartype looks jaggy around the edges, almost like there is no Cleartype at all.

Can this be fixed, or is it just the way Cleartype is?

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up vote 2 down vote accepted

I agree that ClearType loses a lot of its benefits at high DPI and, similarly, when you have giant font sizes.

I covered this in Respecting the Pixel Grid:

I don't understand why Apple is asking us to sacrifice the present at the altar of the future. Can't we have hinting at low resolutions, and accuracy at high resolutions, too? Snapping fonts to a pixel grid may very well be irrelevant when everyone is luxuriating in the glow of their 200 DPI monitors. Until that glorious day arrives, respecting the pixel grid certainly makes text a lot more readable for those of us stuck in the here and now.

These two strategies ...

Apple generally believes that the goal of the algorithm should be to preserve the design of the typeface as much as possible, even at the cost of a little bit of blurriness. (OSX / Safari default font rendering)

Microsoft generally believes that the shape of each letter should be hammered into pixel boundaries to prevent blur and improve readability, even at the cost of not being true to the typeface. (ClearType)

... are in some ways mutually exclusive -- one looks bad at low DPI, and the other looks bad at high DPI.

In a perfect world, we'd dynamically switch between these two strategies depending on what DPI and font size we were using. I am not aware of any operating systems which dynamically switch font rendering strategies at certain DPI levels or font sizes, but they should exist!

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I'm sure fontconfig can <match> by DPI, so it should be able to do dynamic switching quite easily. – grawity Apr 25 '10 at 15:23
Firefox does it, however. There's a setting to define a large font, and it uses different rendering systems based on the font size. You can tweak the settings with the addon Antialiasing Tuner. – trlkly Jan 22 '15 at 22:19

On windows using gdipp we get the best of both worlds, and can switch between the two at will.

  1. Download the latest version of gdipp here.
  2. Before the first <font> rule in the settings file, add:

    <font max_height="13">
  3. Restart your PC (or the gdipp services using services.msc).

This will choose the default windows cleartype rendering for font below 13 in size, and then for larger fonts the default gdipp settings will be used (or whatever other settings you decide to use.

I found "GDI++ tray" and a lot of people claiming windows font smoothing is bad, and that Mac OSX font smoothing is superior. The truth is that mac-style font smoothing is great for large fonts but unreadable for small fonts.

(I know this question is old and "answered" but this was the first result for my google query, and not actually an answer. After extensive searching I came up with my own solution. That's what I am sharing here.)

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