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Re: [CSS21] 4.3.2 Lengths (reference pixel?)

From: Brad Kemper <brad.kemper@gmail.com>
Date: Thu, 16 Dec 2010 07:49:20 -0800
Cc: www-style list <www-style@w3.org>
Message-Id: <B99821AD-045C-40D4-AB54-6F5FF01F450C@gmail.com>
To: Christoph Päper <christoph.paeper@crissov.de>

On Dec 16, 2010, at 1:05 AM, Christoph Päper wrote:

> Brad Kemper:
> 
>> When thinking about resolution, I always think in terms of dpi.
> 
> Might as well be “ppi” or “lpi”.

Lines per inch (lpi) is for halftone dot size, and is something that is really quite different, where in my previous experience dpi still had to be taken into account when setting how fine the lpi was (maybe that's not that big of a factor any more).

I just double-checked PhotoShop, and it is actually "pixels/inch", not dpi. But I think that dpi still probably has a higher recognition factor than ppi as a term. It does for me, anyway.

>> It is what printers and other output devices were measured in
> 
> It’s a “unit” they’re described in, I doubt they’re measured with it.

Whatever.

> 
>> I imagine that in other parts of the world (I'm in the US), dpcm might have been more common.
> 
> No, that’s a CSS novelty as far as I know. Especially for marketing purposes the magical “DPI” is used over here, too.

That's interesting; I didn't know that. If marketing or "buzzwordiness" has made "dpi" recognizable, then that is a plus for us using it too. It makes it easier to learn and recognize and recall. I assume having dpcm also helps with some internationalization for those who are not used to thinking in inches.

> But depending on device class it is (or was) common to list the dot pitch, pixel size or similar in micrometers or millimeters.

Hmm. I don't think dot pitch is quite the right term. That's for monitors, right? We also have to think of printers...

In what contexts are "pixel size or similar in micrometers or millimeters" used to describe resolution?
Received on Thursday, 16 December 2010 15:49:58 GMT

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