Well, it has to do with the resolution of your monitor. Almost every monitor's resolution is 72 DPI. If you save at anything higher for web usage, you are making the file unnecessarily larger.
(Unless you have this thing)

Ben's right. It's meaningless. On the Web, everything* is pixels, and images are either displayed automatically at their full resolution, or at a specified resolution in pixels. The DPI is irrelevant.

T

* Everything meaning all bitmap graphics displayed in native Web formats such as JPEG and GIF. There are of course vector and proprietary formats as well.

Almost every monitor's resolution is 72 DPI.

Wrong. Almost every Mac monitor is 72 dpi, but what's that? Less that 5% of the market? Most Wintel monitors have had a real resolution of 96 dpi for years now, and most new flat screens are 122 dpi or higher. Mine is 133 dpi; my business partner's is 145 dpi; some of my clients have IBM 200 dpi screens. Only Apple are still largely stuck at 72 dpi.

Actually, the assertion that mac screens are 72dpi is also not quite correct either. The operating system renders type at a nominal resolution of 72dpi, but how its actually displayed on a particular monitor is up to the monitor's size and pixel resolution.

Its an easy thing to prove too - just set your monitor's resolution to a different one than it is currently working at and the actual resolution of it in DPI will change, but the nominal resolution that the OS is drawing graphics at will remain at 72dpi on a mac or 96dpi (or whatever) on a Windows box.

DPI is, as fellow hairyface Thomas said, irrelevant.

PS: I work in television and I spend at least 2 hours a week explaining screen resolution to people who think they can take a DVD menu stripped of its navigation and shove it on a poster 5 foot high.

"PS: I work in television and I spend at least 2 hours a week explaining screen resolution to people who think they can take a DVD menu stripped of its navigation and shove it on a poster 5 foot high."

Amen, my brother!

This is interesting.

"PS: I work in television and I spend at least 2 hours a week explaining screen resolution to people who think they can take a DVD menu stripped of its navigation and shove it on a poster 5 foot high."

I get geniunly happy when clients fax me their logos for ads/brochures/whatever.
Imagine the beatiful simplicity of their world. It's 1950's sci-fi.

Thanks for the feedback, all.

I held a ruler to my Mac display and got about 105-110dpi. Toning it down to 1024x768, I got it to 90-95dpi. Nothing came close to 72. Oddly, my 15" Windows monitor at 800x600 was about 70-75dpi; at 1024x768 it was about 90-95. I imagine my classroom's projector would yield a larger dpi, since it stretches 800x600 pixels four feet wide.

But in all cases, the same 100 square pixel graphic remained 100 square pixels. Next time someone asks, maybe I'll underscore the pixel dimensions -- but ask for 1 dpi just to see how they react.

But does 72dpi have anything to do with 72 points in an inch, as in 12 points to a pica?

Ben's right. It's meaningless. On the Web, everything* is pixels, and
images are either displayed automatically at their full resolution, or
at a specified resolution in pixels. The DPI is irrelevant.

Not only that, but the GIF format, which was created specifically for
Internet use, doesn't even store resolution info in the image file.
The 72 dpi thing is just a default it's opened at.

And Ben, yes, the rationale behind the 72 dpi nominal resolution on
the Mac was that one screen pixel would equal one "pica" point.

The orignal macs were 72 ppi (pixels per inch). The original laserwriters were 144 dpi. Twice that of the screen. It was built that way since the mac was a 'graphics' computer from the onset.

However, as other's have stated, it's been a long time since a monitor was actually 72ppi. However, screen resolution certainly has not increased exponentially as much as HD space and Processor speeds have. We're still stuck with monitors that are under 150 ppi for the most part.

The original ImageWriter was 144 dpi; the original LaserWriter was 300 dpi.

I seem to recall some sort of fudge factor switch one could use to make bitmap fonts print better on the LaserWriter, which had to do with 288 dpi being an even multiple of 72. Was it that one could choose to print at 288/300 of nominal size, which would be 96%?

T

Further to my last post: I think that was a switch that made screen-res bitmaps in general print better, not only bitmap fonts.

T

No one is going to talk about the connection to traditional typography?

Where did 72 dots in an inch originate anyway? 72 seems like a very arbitrary number, and for it to have carried over into the digital age is simply because of tradition.

And because you could be sure that on your 72 dpi screen you were seeing type in your layout as it "should" look when printed...but still.

Why didn't traditional printers/typographers use a more round number? say 50, 100, or even 75 dots to the inch?

> that was a switch that made screen-res bitmaps in general print better

You must be talking about the technique where the printer driver would render the letters at twice the chosen point size, and print them at double the screen's resolution, yielding double (quadruple?) fidelity at the same physical size. But the font needed to have the double-size bitmap available in the OS. The olden days indeed.

--

Chris, 72 isn't arbitrary, it's 12 x 6, and 12 has been a cornerstone number since ancient times. The king of Thailand (Rama IX) had his 60th (12 x 5) birthday a couple of years ago, an it was a big deal. Even I had to show up (that's a joke).

hhp

Here's one good reason: It makes it easier to do the math.

72 has a lot of numbers which can be divided into it evenly:
2, 3, 4, 6, 8, 9, 12, 18, 24, and 36. Notice anything
interesting about those numbers? Most of them are
standard type sizes. It made it easy to figure out how many
lines fit into an inch with standard type sizes. Even better,
many of the standard sizes divide evenly into one another
by a factor of 2 or 3. Some standard type sizes are odd (10,
11, 14, 30, 60) or only come out even every 2 inches (48),
but not as many as there would be if a different number
had been chosen.

Try doing the same thing with 50, 75, or 100. With 50 you
get 2, 5, 10, and 25. 75 gets you 3, 5, 15, and 25. 100 gets
you 2, 5, 10, 20, 25, and 50.

Since we use computers to do all our math now, convenient
numbers like 72 are little more than historical habits, but
it's not hard to see why they were chosen in the metal type
days.

> that was a switch that made screen-res bitmaps in
general print better

You must be talking about the technique where the printer
driver would render the letters at twice the chosen point
size, and print them at double the screen's resolution,
yielding double (quadruple?) fidelity at the same physical
size. But the font needed to have the double-size bitmap
available in the OS. The olden days indeed.

Hrant, I remember the technique he's referring to. The
problem was that when you printed 72dpi graphics on a
300dpi laser printer, the low-res pixels would come out
uneven creating a kind of moir� pattern. By reducing the
page to 96%, the pixels would all line up perfectly with the
300dpi dots of the printer. In effect, you converted the
graphic to 75dpi, exactly 4x4 dots per pixel.

"Chris, 72 isn't arbitrary, it's 12 x 6, and 12 has been a cornerstone number since ancient times. The king of Thailand (Rama IX) had his 60th (12 x 5) birthday a couple of years ago, an it was a big deal. Even I had to show up (that's a joke)."

That's interesting. Even then though, how did the use of 12s come into typography? Isn't 7 considered a holy number? One would think that it would all be based on multiples of 7s, especially considering that 7 is still considered an important number today.

:sigh:

Lets just switch to metrics instead.

I would say 7 is a mystic number, not a "holy" one. Certain tuples are also mystic. Recently the phone number 8888.8888 was auctioned for about half a million dollars in China.

BTW, the most rational type measurement system is the one proposed by Otl Aicher (and used in Japan). It's based on the "q", which is 0.25 mm.

hhp

> It's based on the "q"

'q' stands for quark, IIRC?

"Does it have anything to do with 12 points per pica, six picas per inch?

Has this little matter been clarified? � I think we better not go there. What do you think?

Why didn't traditional printers/typographers use a more round number? say 50, 100, or even 75 dots to the inch?

Nien! More than an afternoon.

'q' stands for 'quart', actually.

Gerald:
> Has this little matter been clarified?

I guess so. See Mark's post #316.

'q' stands for quark, IIRC?

No, �quart� - that's the proposed name for the unit.
Aicher was a supporter, and published it in his book,
typographie, but it was actually Josef Rommen who
wrote the proposal.

And I don�t think that this proposal was adopted by the
Japanese as Hrant seems to imply. More probably the
other way around: Rommen�s suggestions may have
been influenced by what the Japanese industry used
already.

This might interest you. ;-)

Only Apple are still largely stuck at 72 dpi.

Typographically we are digitally stuck with type sizes based on 72 dpi. I believe Adobe offers traditional point sizes in Photoshop of all things. But last time I looked PageMaker does not. I suspect that the same is true with InDesign. � John, where are we at with that? Perhaps you know who to ask? This is a software problem, it has nothing to do with Apple. John, do you see what I see? Smiley faces mess with the leading! Or is this only on my Macintosh?

This might interest you. ;-)

My memory doesn�t go that far, thank you. And you see that
Hrant and I have been discussing the same things for four
years at least. What a life! ; )

Oh, and that typometer was really fine.

72 pts. is not equivalent to 72 dpi. The nature of my "traditional" complaint. � I think monitors should not only be based on traditional points and picas but the friggin things should be portrait instead of landscape. I suppose this is not a complaint free zone. Probably it is good that I actually have some work to do.� Anyway, how many points in a pica? Do not say twelve! Please, no guesses. Thank you.

I remember that Typo-L stuff like it was yesterday. I also remember the time (around 2 years ago) that I said "q = 0.25 cm", and you corrected me. :-)

BTW, it would be interesting (if not highly useful) to establish who got it from whom.

hhp

"I think monitors should not only be based on traditional points and picas but the friggin things should be portrait instead of landscape. "

Monitors weren't designed for typographers and designers. I doubt anyone even conceived that people would be doing publishing on computers when the first one was made. Just like no one would ever have figured that a computer that fits in your palm now is several hundred times faster than the first ever built.

I remember an article from an old issue of Scientific American that predicted computers at the end of the 20th century being something like 100 times faster and 1000 times bigger. heh

But there were [are?] �portrait� monitors. I remember seeing one quite
a while ago. Best thing for DTP work.

Rodolfo said...
"Best thing for DTP work."

unless you take into account palettes and spreads pushing
up against the sides of the screen.

In fact for setting anything with facing pages, landscape is better.
Not to mention designing for the screen itself...

hhp

Plus you could say that human ergonomics (especially vision) favor the horizontal.
Hence my website. :-)

hhp

There are 'portrait' monitors, and I guess most of them can be rotated for 'landscape' too.
But, AFAIK, they're too expensive and technically not very good in other aspects.

The only thing wrong with portrait monitors, is that a lot of software doesn't support them...assuming you have one that isn't rotateable. If you can rotate it you're fine, but if you have a plain portrait monitor you're limited to what you can run that won't go off the sides of the screen.

Plus like other people mentioned, what do you do about paletts and toolbars in portrait mode?

The fairly recent laptop/tablet combination PCs are portrait in tablet mode, landscape in laptop mode. This does produce a rather bizarre effect when reading in MS Reader: the ClearType resolution gain is vertical rather than horizontal. Chinese looks very nice

Here's one good reason: It makes it easier to do the math.

72 has a lot of numbers which can be divided into it evenly: 2, 3, 4, 6, 8, 9, 12, 18, 24, and 36. Notice anything interesting about those numbers? Most of them are standard type sizes. It made it easy to figure out how many
lines fit into an inch with standard type sizes. Even better, many of the standard sizes divide evenly into one another by a factor of 2 or 3. Some standard type sizes are odd (10,
11, 14, 30, 60) or only come out even every 2 inches (48), but not as many as there would be if a different number
had been chosen.

Try doing the same thing with 50, 75, or 100. With 50 you get 2, 5, 10, and 25. 75 gets you 3, 5, 15, and 25. 100 gets you 2, 5, 10, 20, 25, and 50.


Well Mark certainly gets the pt.

Chris, you sound like a Luddite. Like one of those old hot metal guys flogging a dead horse. � What's with this? I am not sure if you are attacking the monitor firms or defending them?

Monitors weren't designed for typographers and designers. I doubt anyone even conceived that people would be doing publishing on computers when the first one was made.

It's time for the monitor manufacturers to wake up and "Smell the Pixels". The days of the Three Stooges are long gone with the hoola hoop and Roy Rogers comic books. Speaking of money for old rope. The Howdy Doody Show is over.

Well maybe not!

I mean, hasn't Sony heard of Desktop Publishing? So who is going to tell them.

Us, we are the customers.

Plus you could say that human ergonomics (especially vision) favour the horizontal.
Hence my website. :-)

The jury is still out. Novel yes, yes. Hope you don't mind I Canadianized your spelling of favour. It's not my fault.

plain*clothes: unless you take into account palettes and spreads pushing
up against the sides of the screen.

Software solutions.

John

The fairly recent laptop/tablet combination PCs are portrait in tablet mode, landscape in laptop mode. This does produce a rather bizarre effect when reading in MS Reader: the ClearType resolution gain is vertical rather than horizontal. Chinese looks very nice

Buy an English Speaking monitor, have Sony translate, or better yet, click on the "Portrait Cleartype Function."

I am not sure why it is our job to defend the economic giants in their refusal to make the world a prettier place to set a page in. They should do something about it. Spread sheets are a separate issue. They need panoramic screens. But be patient, I am still waiting for the "Blue Moon".

Am I just seeing things or does the smiley faces mess with the leading? When is Adobe going to Postscript the web?

Yup, those smileys are messing with your leading.
You can avoid them by using 'pure-text' smileys like:

: )
:-)
; )
;-)

And so on...

Eduardo,

Sigh! Maybe I don't use happy faces! Nobody laughs anyway.

Thanks.

Eduardo,

About that grey~

I'm a luddite? Hah. I embrace technology.

The fact of the matter is though, computers are not designed for subsections of users, they're designed for everyone. Which is why you can use InDesign, close it, then load up Halo and kill a few bad guys all on the same computer.

There are monitors that are designed for graphic artists in mind; they have better colour and are tweeked to provide the best image possible, but they still have to conform to the standards that have been laid down.

Portrait monitors are rare because they just don't meet the standards. And people would rather have a widescreen monitor today than a tallscreen monitor. The better to shoot the alien bad guys with or watch the latest DVD.

Shoot the alien bad guys,

Poor Muslims, you and Rumsfeld.

Obviously I was confused, I thought you said this was the problem.

The only thing wrong with portrait monitors, is that a lot of software doesn't support them.

That is the only real problem. And the reason the software doesn't support them is because people want landscape monitors.

Chris,

Rodopho: But there were [are?] �portrait� monitors. I remember seeing one quite
a while ago. Best thing for DTP work.

How would you explain this? Are you saying Brazilians are not people? Or some folk in Finland! I care to disagree with you. What makes you think present software will not work. I am sure software could be optimized. Frankly I have my complaints about the optimization of landscape. I would say software does not support them. Always we can complain. I am good at it. � I had used Aldus Pagemaker in 1989 on a portrait monitor with great preference. People in those days wanted portrait. Then again in those days we were not speaking of playing games. Those monitors were great, not the resolution, but the flexibility. You could use them either way, they swung.

You could still shoot Aliens. Think about it Chris. Wouldn't that be cool?

Why would you want portrait? Seriously, what would you see as the benefits? Even for book design -- in which you might point to the fact that pages are portrait -- it is much more useful to see a spread than to see an individual page. Even for tall, narrow folded pieces like brochures, what you really want to see is how it looks when unfolded, not the individual panels. I simply don't see any compelling reason to prefer portrait to landscape for design work.

John,

You could use them either way, they swung.

Even for book design -- in which you might point to the fact that pages are portrait -- it is much more useful to see a spread than to see an individual page. Even for tall, narrow folded pieces like brochures, what you really want to see is how it looks when unfolded, not the individual panels.

Huh!!!

You do,I don't!

The negative magnifying glass takes care of the few times you, or should I say I, want that. Better yet, hit the print button. After sitting around gawking you have to get your hands out of your pockets and get in there and actually do something.

For instance I have a spread here I would defy you to work on in landscape. Not without a major cropping bleed which defeats your very suggestion.

You are not killing aliens too are you John?

Oh boshe moi...

I did not deny the fact that there were and are portrait monitors in existance.

However, only a small, teeny tiny, miniscule, insignificant, molecular in scale�someone give me some more synonyms for small�group of people want or need them.

Who back in 89 wanted portrait monitors other than yourself? Who HERE wants one other than yourself? I would much rather, and so would several other people here, see spreads than a single page while doing layout...magnifying glass be damned.

If you can't work on the particular spread you mentioned in landscape, that is obviously your deficiency since no one else seems to have a problem. And since a few companies do still sell portrait monitors I suggest you look into buying one.

Software can be optimised for portrait display. The new Tablet PCs are primarily portrait since they mimic, well, a tablet. But you can't run all applications in tablet mode, despite the fact that the OS supports it.

The swinging portrait displays were based on firmware solutions. Which would also take care of John's Chinese Clear Type complaint. � I suppose I am the only one that actually does not shoot aliens. Otherwise you would all want what is so obvious I find it embarrassing we are even having this discussion. � Pretty childish. Where is my channel changer, I have a bleeding book page to look at? � Beware of aliens, they are coming to get you. � In other words kids, I got work to do? Anyway, don't let me get your goat. You should be warned though. I had a lawyer friend who ruined his practice by using the office computer for a golf game. I'll bet he wished he had a portrait monitor. Imagine golf on a screen like that? Not much fun. � Poor bugger I totalled his wifes brand new BMW. You want to let me borrow your BMW? I understand.

Portrait monitors are better for one thing: designing single pages (like posters), which are generally vertical. Make that two things: nude photos.

hhp