Shuttleworth: Unity on Wayland

Posted Nov 6, 2010 10:55 UTC (Sat) by GhePeU (subscriber, #56133)
In reply to: Shuttleworth: Unity on Wayland by hschildt
Parent article: Shuttleworth: Unity on Wayland

Ubuntu is correct in moving forward past the blurry fonts of X.org and the retarded Gnome desktop.

What the hell has X.org to do with "blurry fonts"? The fonts are rendered by freetype, who's not a part of X.org, and nobody is going to touch it. What are you going to blame X for now, the rain on weekend days while it was sunny all the rest of the week? Poverty and famine in Africa?

If the price for "getting past the 1 percent market share" is a new influx of fanboys who talk with arrogance about things they don't know and spout out the worst idiocies, even in a place where usually you could find interesting commentary, then I'd really prefer to stay with the current usage level, thank you very much.

Shuttleworth: Unity on Wayland

Posted Nov 6, 2010 19:39 UTC (Sat) by alankila (guest, #47141) [Link] (6 responses)

I'm probably indirectly feeding a troll, but I can tell you that the real problem why Linux has bad fonts -- I won't call them blurry because I don't find that meaningful criticism -- has to deal with too few people understanding how fonts should be layered on top of the existing graphics.

To explain it in simplest term, a diagonal like \ or / requires drawing partially eclipsed pixels to eliminate jaggedness of the monochromatic rendering. Assuming a white background and black foreground, Linux people seem to think that a half coverage of black within that white pixel should result in color 0x80 because that is 50 % blend between 0x00 and 0xff. This is, however, wrong, because of gamma. To render a physical intensity that is close to 50 % of the brightness of white, you will actually want to use color value 0xb4. 0x80 is simply way too dark.

I am demoing this problem on this page with the green text on purple background: http://bel.fi/~alankila/lcd/

The reason nobody does this right is that to X, and pretty much everyone else, text is just an ARGB pixmap, and libraries like cairo get the text up from freetype (which is not the faulty party) in linear alpha space, and turn that into linear ARGB bitmap with subpixel positioning. However, this bitmap eventually ends up on a sRGB surface, and the intermediate colors are destroyed, giving the color fringing and darkening artifacts that I try to demonstrate as prominently as I am amble.

Shuttleworth: Unity on Wayland

Posted Nov 6, 2010 20:25 UTC (Sat) by quotemstr (subscriber, #45331) [Link] (2 responses)

So where would be the best place to implement gamma-corrected compositing? New XRENDER primitives?

Shuttleworth: Unity on Wayland

Posted Nov 7, 2010 14:09 UTC (Sun) by alankila (guest, #47141) [Link]

A solution along those lines has been suggested, at least. Changing the whole texture blending algorithm to do gamma correction would break all applications that assume the current behavior.

Shuttleworth: Unity on Wayland

Posted Jun 8, 2012 7:59 UTC (Fri) by alankila (guest, #47141) [Link]

Old thread but I did actually implement gamma-corrected XRENDER. Not every application is correctly rendered yet, but most are...

http://bel.fi/~alankila/lcd/linuxgc.png

Shuttleworth: Unity on Wayland

Posted Nov 7, 2010 3:52 UTC (Sun) by jwb (guest, #15467) [Link] (2 responses)

It's funny you should mention this. I used to complain about the lack of gamma-corrected Freetype and Cairo rendering on mailing lists roughly 5-10 years ago. At that time I was repeatedly assured that of course this would be implemented quite soon. And yet it never was.

Shuttleworth: Unity on Wayland

Posted Nov 7, 2010 10:07 UTC (Sun) by HelloWorld (guest, #56129) [Link] (1 responses)

Well, you could open a bug report or ask again :).

Shuttleworth: Unity on Wayland

Posted Nov 7, 2010 14:05 UTC (Sun) by alankila (guest, #47141) [Link]

I already have a bug open with cairo about this. They are aware of the problem and understand this. The folks there seemed sympathetic to my cause and even told me the name of the person who was supposedly working on it... The idea is to support textures in different color spaces, so they are supposedly planning to solve the whole problem at once.

Hopefully they aren't chewing too large a piece. At this point I could live with almost any kind of unspeakable kludge, rather than wait 10 years for the perfect solution.