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#1 2013-02-27 02:09:50

greenaim
Member
From: Portugal
Registered: 2011-11-08
Posts: 12

DPI, pt units, font size, different screens, real physical size?

Hi,

Usually the default dpi are 96dpi but we can set our screen dpi... But the only application I know that seems to work is in the evince(pdf reader) where I can very accurately see the real size of a paper/document... 


I've 2 laptops now, and I was expecting that setting the correct DPI in each laptop they would display the same font size... for example in urxvt where you set the font size in pt units... But this doesn't happens...

Actually, I was expecting that the fonts displayed in the screen had +- the same size of the ones printed on a paper... But I can't achieve that.

Anyone can explain this? Our point me the right place where I can read about this?



Thanks

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#2 2013-02-27 10:19:12

swanson
Member
From: Sweden
Registered: 2011-02-05
Posts: 759

Re: DPI, pt units, font size, different screens, real physical size?

Here's a link to a screen DPI calculator; http://members.ping.de/~sven/dpi.html

Sorry to say, but I can't help you more. Recently my screen DPI went haywire for some apps like urxvt, but not for others. I posted about it but got no help at all.

But since my years in the printing industry I know that in Europe a point (pt) is 0,353 m m. So if you get that constant on your screen you've got true WYSIWYG. But it seems that these measurements aren't important in the linux world.

Hope it helps on the way ...

PS wikipedia: http://en.wikipedia.org/wiki/Point_(typography) where they define a postscript point as 0,3527 mm.

Last edited by swanson (2013-02-27 10:25:18)

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#3 2013-02-27 10:29:15

brebs
Member
Registered: 2007-04-03
Posts: 3,742

Re: DPI, pt units, font size, different screens, real physical size?

Here's a discussion on DPI. And another, since you mention urxvt (which doesn't even use fontconfig).

In short, it's legacy compromises.

Edit: More xorg DPI arguments.

Edit2: To set an override for xf86-video-intel, at the start of ~/.xinitrc, use e.g.:

xrandr --fbmm 383x212

Then check in xorg:

xdpyinfo | grep -B1 dot

Last edited by brebs (2014-04-13 10:56:52)

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#4 2013-02-27 11:37:36

swanson
Member
From: Sweden
Registered: 2011-02-05
Posts: 759

Re: DPI, pt units, font size, different screens, real physical size?

Well, some people want the best visual rendering of fonts on their screen and set the dpi along that criteria. A few want to see that their printed material corresponds to what they're doing on their screen. These are of course completely different view points. Those in the linux printing industry are a minority that's why beautiful font rendering has a majority of threads. CMYK handling is not that good either.

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#5 2013-03-01 02:23:14

greenaim
Member
From: Portugal
Registered: 2011-11-08
Posts: 12

Re: DPI, pt units, font size, different screens, real physical size?

brebs wrote:

Here's a discussion on DPI. And another, since you mention urxvt (which doesn't even use fontconfig).

I've read and I need to read more... The first link is exactly what I was trying to ask...

I thought that setting system dpi was simple... but there's always thw problems of legacy...


One question, I use xrandr to set dpi should I use another way?


Thanks all, as I said I'm going to read more... I just wanted to have same font size in 2 different screens...

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