What do you think, should I activate ClearType before doing screencaps or not?

IMO it looks better, but I'm concerned that PNG algorithm cannot compress it well.

Comparison:
Image captured without ClearType
Image captured with ClearType enabled

I think the lower image looks better. But it is also 2kB larger despite the smaller size.

FYI, I capture the screen using HardCopy Pro, then I save using the PNGOUT plugin of IrfanView32. This plugin performs multi-pass optimization on PNG images, and configure it for maximum compression (i.e. keep doing another pass until there is no size advantage) so I can assure you that the PNG files above are the smallest possible.

Personally, I hate ClearType since the text looks somewhat blurred IMHO.

I'd have to agree with Sebastian Mares. It looks blurry to me too.

IMO, Cleartype helps on LCD screens. On a CRT it can look blurry thou.

I just got a 17" ViewSonic LCD (1280x1024) for the new PC I built, and ClearType is not that great. Maybe the LCD isn't the best out there but I thought ClearType was supposed to make things look better, I must say it looks almost as irritating on the LCD as it does on my bland-beige CRT.

EDIT: And yes, I tried the ClearType Tuner.

BTW, I also have an LG Flatron TFT (18").

Every ClearType mode I've seen just looks like a blurry mess, even on LCD's.

The anti-aliasing that Apple uses in OS X is slightly little better, but I still get rid of it when I can - especially for text I tend to read often, such as Terminal windows.

I say do whatever is faster. If you use ClearType normally, then stick with it. Having to turn it on and off just to take screen caps would get very tiring IMO.

It's also a different image, so it's a bit difficult to determine if the compression is worse or better from this.

Personally, I don't like ClearType. It indeed seems to be a bit blurry.

I have ClearType enabled, however I do have a rather nice LCD a DELL 19 inch 1901FP which I think "may" just be a re-branded Sony LCD. I had to use the Microsoft ClearType Tuner PowerToy because without its adjustments the on-screen text looked blurry, mostly the desktop icons text. After tuning it's now rather sharp looking and I can't complain one bit as seen here.

I fear to get eye cancer from cleartype only use it with black sunglasses

no, seriously, I really don't like it on any LCD screen I used so far

Doest't cleartype only work if you use a digital connection to a LCD? Otherwise it's a bit screwed up, no?

It certainly helps in my laptop. It is extremely annoying to read texts when it is disabled.

i also have an LCD and it pretty much sucks. the only thing ClearType is capable of doing is hurting my eyes.

There was a topic about it some time ago.
There's no point in using it with screencaps, unless you're sure that everyone who will be watching them has a digital LCD.

I have it turned on. I noticed that the specific fonts displayed have a big impact on readability with it that way. Segoe UI in particular is pretty ugly with it on. Tahoma and Verdana do very well with it. Far more annoying was the Times New Roman capital letter 'O' stop sign/'0' hexagon phenomenon with it turned off.

I'd rather have rounded letters actually look rounded without making the fonts larger, at the expense of some apparent blurriness. (Always used it with CRTs--Philips 107P, now using it with LG Flatron L1730S and Dell Inspiron 8200 UXGA) I replaced the cheapo analog cable that came with the L1730S with a more expensive properly-designed cable and it helped a lot with clarity.

ClearType looks very blurry on my CRT monitor, it's annoying.

Guys, maybe this topic will help: http://en.wikipedia.org/wiki/Cleartype

Ah, thanks. Very helpful. Buried deep in the wikipedia text is this:

Guess my next screencaps will be done with ClearType off. No big deal. Must reset the computer anyway after playing Civilization IV

I own an IBM P275 CRT and IMO ClearType (@1.2) definitely helps there.