From 64515718b77f0ddd446cdb016c46ed658a14c71b Mon Sep 17 00:00:00 2001 From: Werner Lemberg Date: Mon, 17 Aug 2020 09:00:33 +0200 Subject: patents.html: ClearType patents have expired. --- patents.html | 125 +++++------------------------------------------------------ 1 file changed, 9 insertions(+), 116 deletions(-) diff --git a/patents.html b/patents.html index bbc5f01..1652618 100644 --- a/patents.html +++ b/patents.html @@ -90,11 +90,13 @@ -
-

ClearType Color Filtering Patent Issues

+
+

The ClearType Color Filtering Patents Have Expired!

-

A survey from June 2007 shows no less than ten patents - from Microsoft that cover ClearType.

+

Since August 2019, all patents related to ClearType color + filtering have expired worldwide.

+ +

The affected patents were

@@ -150,7 +152,7 @@ pixel sub-components of a display device

-

Essentially, these patents cover several different +

Essentially, these patents covered several different things, which can be grossly sub-divided into

    @@ -174,120 +176,11 @@ Hitchcock's whitepaper.

-

Patent Claims, Prior Art, and Validity

- -

Steve Gibson claims that - the technique used by - ClearType is a reinvention of a 20-years old thing used on - the Apple II. His exact words are

- -
-

Thus, Microsoft's ‘ClearType’ application of - sub-pixel text rendering does not represent the dramatic - breakthrough that they claim and it can not be the - valid subject for intellectual property - acquisition.

-
- -

(emphasis added).

- -

Unfortunately, we believe that Mr. Gibson doesn't - understand patent law well. Under the current US regime, - any minor improvement to a previous technique can be - considered an ‘invention’ and - ‘protected’ by a patent under the right - circumstances (e.g., if it is not totally trivial). If we - look at - the first - ClearType related patent mentioned above, we see that - the Apple II - Wozniak patent covering this machine's display technique - is listed first in the patents' citations. This - shows that both Microsoft and the patent examiner who - granted the patents were aware of this ‘prior - art’.

- -

We are not trying to defend Microsoft here, just wanting to - avoid feeding false hopes to people who would like to see - the patent revoked.

- -

Another popular view is - that these - patents are too general to be enforceable. Well, to be - fair, some of the claims in these patents do indeed use - rather vague descriptive terms (even for a patent lawyer or - an ‘expert in the field’). This is - absolutely not surprising, it is a direct - consequence of how the patent game works.

- -

We won't cover this in greater detail since there - are many - interesting - pages - on the subject. However, in case you invalidate a single - patent claim (e.g., with prior art), that doesn't mean the - whole patent is busted. Any other independent and - dependent claim can still be enforced.

- -

Some of these patents have up to 40 claims. Invalidating - them is going to need serious prior-art, even if - there are also strong chances to invalidate the most general - claims in there. For example, many of the cheap LCD screens - on digital cameras have used a screen where each pixel is - either red, green, or blue, with colour images directly mapped - to them; they have been doing it for years, even when - displaying text or menus, and this corresponds exactly to what - the most general claims cover. If we can find a proof that - the technique was deployed before the patent's filing date, we - could have valid prior art to bust these.

- -

Possible Work-Arounds

- -

People have proposed alternatives to the ClearType color - filtering method. A very good example is - the SubLCD - technique, which employs a different way to use sub-pixels - compared to Microsoft's ClearType implementation. Its - author even says it doesn't infringe the ClearType - patents.

- -

Unfortunately, the FreeType team doesn't share this - enthusiasm. The reason is precisely the very vague patent - claims described previously. There is a non-negligible - (even if small) chance that these claims also cover the - SubLCD technique. The situation would probably be different - if we could invalidate the broader patent claims, but this - is not the case currently.

- -

Does FreeType Implement Any of the Patented Techniques?

- -

Technically, no. The patents cover the whole process of - generating and displaying sub-pixel images. Since the font - engine doesn't do the display part, it cannot infringe. - Apart from that, FreeType has provided the capability of - converting vector shapes into un-filtered sub-pixel images - for a long time.

- -

By default, FreeType's scan-line converter returns - ‘gray’ sub-pixel images, where for each pixel - the color components are equal (this is, R=G=B). The result - is visually identical to gray anti-aliasing and cannot - infringe any of the ClearType patents.

- -

Similarly, the LCD-specific filtering API is disabled by - default, which means that it returns an error and doesn't - alter sub-pixel images.

- -

You can override these limitations by activating option - FT_CONFIG_OPTION_SUBPIXEL_RENDERING in - FreeType's ftoption.h configuration file, but - you should do that at your own risk.

-
-

Last update: 13-Feb-2018

+

Last update: 17-Aug-2020

@@ -354,7 +247,7 @@ Bytecode Patents
  • - Other Patents + ClearType Patents
    • -- cgit v1.2.3