Hardware Cleartype in WinXP?

[zandor]

I'm generally a shadow mask fan for home use. Trinitrons seem a bit more grainy thanks to the square pixels, and it generally seems like you get more resolution out of a shadow mask tube at a similar price point.
OTOH, the trinitrons are usually brighter, so that's what I use at work. I'm next to a window & we've got fairly bright flourecent lighting.
I guess I'll have to play around with glyph antialiasing, though at 1600x1200+ I have to wonder if the difference will really be noticeable.

[Jussi]

So excuse me for repeating myself : does Parhelia's glyph antialiasing feature offer anything new in terms of picture quality? Is it all about speeding up the "standard" smoothing? I was really hoping to see a feature providing cleartype-like fonts on a crt display. I want the smaller fonts to be even somewhat smoother, not just the headings.

[Ryu Connor]

http://www.matrox.com/mga/products/parhelia512/technology/glyphaa.cfm

Parhelia-512 is the first graphics technology to provide hardware acceleration for antialiased text and font rendering with full gamma correction—a feature currently available in Microsoft® operating systems but only accelerated in software. Furthermore, Matrox has taken Microsoft's text quality initiative one step further by offering programmable gamma correction for text antialiasing. While certain competing GPUs accelerate the antialiasing of text in hardware, they do not apply gamma correction during this process. Gamma correction during the antialiasing process is imperative for the accurate rendering of antialiased text. With Glyph Antialiasing, users have the ability to adjust gamma levels independently in order to have text antialiased according to their preferences. Enabled by Matrox under Windows® XP and Windows 2000, Glyph Anitialiasing makes onscreen text more readable and provides the ultimate desktop viewing experience—without compromising performance.

It's not Cleartype as it works in 2000. I don't think it's the default smooth font edges found in the effects tab of the display properties either as 9x has a similar technique. I guess it's some function of the 2000 and XP GUI that is typically left disabled. It seems Parhelia will turn it on and will do it in hardware.

http://www.matrox.com/mga/products/tech_info/pdfs/parhelia/glyph_aa.pdf

This PDF serves up a great deal of info about the feature, but it doesn't answer the question of what it is (smooth edges or something else).

[Cheesekeeper]

According to the AtomicMPC article (I seem to be quoting them a lot lately ):

Glyph Antialiasing samples the text at higher resolutions, then scales it back using up to 16 shades to display the text outline. This system is similar to the Clear Type feature in XP. Although mainly designed for LCDs, many users have reported improvements with CRT monitors as well. The Parhelia accelerates this in hardware, freeing the CPU which may otherwise take a performance penalty of up to 30%. The Parhelia also allows for programmable gamma correction for Glyph AA.

(The above text was paraphrased from the article: I didn't want to type in the whole paragraph)

Its function is to make text edges look smoother, without having to take a performance hit.......

[jonhart]

Cleartype on CRT

Although trinitron CRTs use vertical stripes, you still cannot use Cleartype effectively on them

The reason is that in an LCD a given pixel is made up of three sub pixels, and the order and relative location of those sub pixels never changes.
In a CRT ( even a trinitron ) the components that make up a pixel are not physically bound together. If you adjusted your screen to the left or the right then the order of the three colours could change. In addition, if you arent running at the screens max resolution ( which you probably arent ) a pixel may have more than one set of colour components constructing it.

The result of this is that you shouldnt use cleartype in a CRT, just the normal grayscale anti aliasing.

An example:

In an LCD -

rbG RBG Rbg

A perfectly setup CRT ( trinitron ) -

rbG RBG Rbg

A real life CRT ( trinitron ) -

bGr BGR bgR

little letters are 'off subpixels', and big letters are on. In a real life trinitron you end up with gaps between the sub pixels, which arent meant to be there.

You could achieve a perfect setup for a CRT, but it changes over time, unlike an LCD. It just isnt worth the effort for the typical user ( and hence microsoft ).

[Cheesekeeper]

Just tried on my monitor (a 21" Platinum Trinitiron) - standard font smoothing looks quite good, but ClearType looks blurry and awful.......

[Michel Carleer]

Very good point indeed jonhart, as cleartype indeed approximates grey shades with colours, using the sub-pixel colour element closest to the stroke of the character.

[SuRGV]

I've enabled Cleartype on my machine with Samsung 955DF (19') @1024x768x32 and love it. Standard smoothing does not make any difference at all compared to regular setting.

[az]

So (sorry if it's a little bit off-topic), doesn't Cleartype produce "colored" edges?

P.S. I doubt Parhelia supports ClearType, they would have stated that. I think it's just "standard" font-smoothing, using their Fragment AA engine in Windows, taking load off the CPU.

AZ

[Michel Carleer]

Yes, Cleartype produces coloured edges. But viewed from a normal distance and because it is so small (1/3rd the pixel pitch), the eye does not see the colour although it sees the luminance gradation.

[Rob(QG)]

I just turned Cleartype on, on my shadow mask monitor.

Results are a bit mixed.

Medium size fonts like this have better shape than with normal smoothing. Smaller fonts, however, show up the blurriness quite badly - especially towards the corners of the screen where it is amplified by the imperfect alignment of the electron guns in my cheap monitor.

Gonna have to save for a nice TFT, I guess.

Does it work on plasma displays? (in case the savings go well )

[Yannick]

Yes, ClearType on other monitors than LCD cannot work as good, because of the fact that the screen resolution never matches the pitch, as jonhart explained.

But, depending on you resolution, font sizes and screen pitch, it may still produce a good result.


While it's true that, on my screen (which is a Diamondtron NF, which is, IIRC, a Mistubishi-designed flat screen, trinitron-like tube) standard smoothing may look better than ClearType, there is a noticable improvement on small fonts.

Small fonts do look quite blurry. But because of the fact that ClearType can emulate sub-pixel thickness for vertical lines, the very small fonts look thicker (more than the single pixel of the true font : don't forget that standard smoothing is disabled for small fonts under Windows), while moderately small fonts (those that are two pixels thick) are thinner. In both cases, the letter, although blurred, looks much more similar to a printed character.

Joined is a small bitmap comparing the three techniques in Windows Explorer, with Windows set to large fonts. First is everything off, second with smoothing (which does nothing on small text) and third is ClearType. This picture has been zoomed 2x

[EvilDonnyboy]

My Samsung 19" 900NF has a NaturalFlat (mitsubishi) Apeture Grille tube with a .25 stripe pitch. At 1280x1024 and lower clear-type looks like a blurry mess, like everyone else.

But at 1600x1200 and above, clear-type all of a sudden looks much better than standard text smoothing. I guess it has something do do with the size of the stripe-pitch and resolution.

[az]

Very nice pic, Yannick, thanks (btw, doesn't yannick mean "child" in some indian language?)

While the colors with cleartype are very noticeable when viewing your pic at 100% (really 200), they get much more tolerable at 50% (on a 19" at 1152x864, which won't go higher, unless I want total bluriness ), although it looks a little like a convergence problem (which I personally find quite annoying).

So this is a great tech with high resolutions/small dot pitches, but not so great for lower res.

AZ

[Phoenix]

Parhelia implements the "standard" glyph AA found in 2k and XP in HW, but you also get to control the text gamma - in short, you have a separate control making glyphs look "fatter" or "thinner" (which in fact controls the brightness of the blended pixels).

Be careful when checking glyph AA - there's a minimum font size below which glyph AA won't kick in, and some apps don't have their glyphs AA'd (don't know why).

Check with NotePad or WordPad using Arial around 16pt (16pt shows glyph AA in 1280x1024, small font). You should see it.

Phoenix.