antialias

"A technique used ... to make diagonals ... appear smoother" [1 ]. Commonly applied nowadays in typograpy: "The most common example is black characters on a white background." Microsoft first announced its breakthrough new display technology, dubbed ClearType at November 1998 Comdex. According to Steve Wozniak, however, Apple II programmers were using these techniques twenty-two years earlier.

KPV A really good article on how it works vis-a-vis sub-pixel font rendering can be found at [2 ].

Lars H: Another resource (which is almost a textbook) on it is http://www.rastertragedy.com/ .

[... relate to TrueType, TkGS, Good Looking Tk, Nextgen Tk, Revitalized Tk, Xft support, ...]


Antialiasing is not an unalloyed good, as Joel, for example, recognizes in his "Three Wrong Ideas ..." [3 ].

DKF: I'm not sure that I agree with Joel. But bad antialiasing isn't worthwhile, I'd agree.

JE: Joel's argument against antialiasing is a total strawman. He demonstrates that if you take text rendered in a well-digitized bitmap font, then blur it with COREL PHOTO-PAINT, the blurred version looks worse. Well, duh! Properly antialiased text often looks better than bitmapped fonts.

KPV: Of course its a matter of taste, but I've never liked antialiased fonts. To my eye they seem to have a blurry color which I find distracting.

WJR: When it's done right, antialiasing can result in better readability and comprehension. I'll dig up some references that attest to this, but I seem to remember an article by Jakob Nielsen discussing Microsoft's ClearType technology.

KPV Information on Microsoft's ClearType can be found at [5 ], including the article by Jacob Nielson [4 ] which claims that "ClearType will make this user at least 10% more productive while reading from the screen." The side-by-side example they give is totally canned in favor of ClearType--both by using italic text and by using a wretched font. As a better experiment, just display the same text in a tcl/tk text widget using a better designed italic font like Tahoma or Arial and compare it to the ClearType example. To my eye, they're both very readable but the ClearType is annoyingly fuzzy and slightly colored. YMMV

WJR: When you say they, I assume you're talking about Microsoft's example. It wouldn't surprise me if Microsoft's study contained some confounds. As for Nielsen's article, I imagine it's based on some real usability metrics, so I'd place a little more trust in it.

TV In computer graphics, anti-aliasing is usually to prevent artifacts in images which usually become indeed neater to look at in the process, for instance when a ray-tracing image 'shoots' more than one ray per image pixel to make edges not artificially 'gridded' to the pixels in the image. The colouring can be a result of an antialiasing, or resolution enhancement simulation making use of the fact that pixels on a CRT or other screen are composed of usually red, green, and blue, which are arranged in some constellation per image pixel, and the per colour pixels are 1/3 of the size of a 'whole' image pixel. Alternatively, it could be that a screen with a small number of RGB quantisation values, or a small colour table (or software which runs on a better screen but thinks/acts limited) does a bad job at creating intermediate grey levels by setting unequal rgb components.

Anyhow, relation with tcl/tk, uh, Tk issues, theming and visual appearance issues.

Michael Heca Antialising is needed for using Tcl/Tk to make presentations. First question from graphics is if Tk have antialiasing and alphablending.

TV Really? Never crossed my mind.

wdb I need antialiasing to be happy. Sadly, canvas doesn't have it.

DKF: Tk 8.5 will antialias all text it displays (except on X11 when built without xft support) and it does support alpha blending of images (assuming you've got an image with an alpha channel). But for presentation work you probably want tkzinc...

RS Another option for antialiased canvas items seems to be tkpath.

fr since Tk8.5, it is a compile-time option, if you do not want antialising, use --disable-xft to configure Tk.

DKF: Just noting that if you've got antialiasing set up right (including subpixel hinting) then antialiased text looks awesomely better than old text. It's genuinely more readable. But the setup of the OS/platform's font rendering engine needs to be done correctly, and there's nothing that Tk can do to help you. (FWIW, Tk on Win and OSX has been antialiased for a long time and nobody complains. The issue seems to be bad configurations on some Unix ? particularly Linux ? distributions.)