Image resolution on HTML page

[shapper]

Hello,

When displaying an image on a HTML page, in this case I am using PNG,
should I use 72 DPI or 96 DPI?

I though it should be 72 DPI but I have seen a few examples with 96
DPI.

What is the advantage of using 96DPI?

Thanks,
Miguel

 

[C A Upsdell]

Hello,

When displaying an image on a HTML page, in this case I am using PNG,
should I use 72 DPI or 96 DPI?

I though it should be 72 DPI but I have seen a few examples with 96
DPI.

Image sizes are measured in pixels, not inches. Ignore the DPI issue.

 

[dorayme]

Hello,

When displaying an image on a HTML page, in this case I am using PNG,
should I use 72 DPI or 96 DPI?

"When I eventually begin to make a Portuguese meal for dorayme, how big
should I make it, what size plate should I use, what are the advantages
of a big meal over a small meal. Should I use a big pot to cook it in?
What if I want to make a small meal, is it not a waste to use a big
pot?"

 

[dorayme]

so if the dpi was 600 that would be ok?

Ignore dpi, says the man, but would 600 of them would be OK? Perhaps so
many could not be ignored! <g>

Anyway... The dots per inch is unit measurement for paper printers. 600
dpi is ok if you want 600 dots to be printed per inch and the person
printing it prints it at 600 dots per inch. It may be OK if he does not
but prints it at 1200 dpi (the whole pic will be smaller in inch size,
the dots packed in tighter). It may be acceptable to him if he prints it
at 72 dpi (it will be much bigger in inch size, though not as rich in
quality, the dots spread out more)

i was brought up to believe that dpi for web was 72

The dot per inch is unit measurement for paper printers but if you are
preparing pictures for the web it is more usual to set them in pixels.
You need not worry how many exact pixels per inch will be displayed
because it will vary from monitor to monitor depending on how the
resolution is set. On my old SE/30 Mac a pic made to be 432 x 432px will
be 6 x 6in. On a more modern monitor it might well be only about 4 x 4in.

If you want a simple rule for websites:

A *useful* thumbnail: 150 x 150px

A medium enlargement (safe for dial up if you compress without losing
too much quality): 600 x 600px

A slightly daring but still "pushing it" enlargement: 800 x 800px

 

[rf]

Hello,

When displaying an image on a HTML page, in this case I am using PNG,
should I use 72 DPI or 96 DPI?

Where exactly would you set this DPI for a png image? There is no HTML
attribute nor CSS property for DPI and there is nothing in the png file
format specifying DPI. png (and images in general) is about pixels, not
inches.

Perhaps you mean when you use your image composer or whatever to save the
image. In that case this is merely telling the image composer how many
pixels there are in a mythical "inch" so it can figure out how many pixels
wide the image will be when you tell it to save the image 6 inches wide.
Tell it there are 96 pixels (or "dots") per inch and it will save the image
576 pixels wide.

I though it should be 72 DPI but I have seen a few examples with 96
DPI.

Where?

 

[Travis Newbury]

If you want a simple rule for websites:
A *useful* thumbnail: 150 x 150px
A medium enlargement (safe for dial up if you compress without losing
too much quality): 600 x 600px
A slightly daring but still "pushing it" enlargement: 800 x 800px

I have read quite a few studies on using Fibonacci's golden ratio in
design, music and when displaying images.

http://desktoppub.about.com/od/gold...io_Phi_and_the_Golden_Rectangle_in_Design.htm

It seems for one reason or another these are more appealing to
humans. So I would take your image sizes and use the golden ratio to
tweak their size.

 

[Travis Newbury]

"Should I use a big pot to cook it in?
What if I want to make a small meal, is it not a waste to use a big
pot?"

Based on the question in this group from this person, I am so hoping
he posts the url to his newly created site...

 

[Doug Miller]

I have read quite a few studies on using Fibonacci's golden ratio in
design, music and when displaying images.

The concept of the Golden Ratio predates Fibonacci by approximately seventeen
centuries. Its discovery is generally attributed to Pythagoras, and written
definitions of it are at least as old as Euclid.

http://desktoppub.about.com/od/goldenrectangle/Golden_Ratio_Phi_and_the_Gol=
den_Rectangle_in_Design.htm

It seems for one reason or another these are more appealing to
humans. So I would take your image sizes and use the golden ratio to
tweak their size.

Do you mean change the width and/or height, so that they're all golden
rectangles? What if the image is inherently a square? Or inherently a long,
narrow rectangle such as a panoramic landscape photograph?

 

[William Gill]

Hello,

When displaying an image on a HTML page, in this case I am using PNG,
should I use 72 DPI or 96 DPI?

I though it should be 72 DPI but I have seen a few examples with 96
DPI.

What is the advantage of using 96DPI?

Thanks,
Miguel

What everyone here is saying is DPI (dots per inch) is a specification,
not a measurement, intended for print reproduction. 72dpi tells the
printing mechanism "space your dots evenly so that 72 of them fill one
inch. (or 5184 of them fill one square inch)" Visual media (i.e. a
computer monitor) have the dots, called pixels (or picture elements)
spaced by the display resolution settings. Specifying pixel spacing for
the image is pointless, at least today. I believe the 72dpi you see so
often has Mac origins, and I think can be traced to thinking of the
screen like a different form of paper, thus images were thought of as
being "printed" to a display monitor. I don't remember, but I believe
way back when, graphics programs did in fact take the dpi specification
and interpret them to make the right screen translation. Whether that
is right or wrong is irrelevant. If you have an image that is 300
pixels high and 500 pixels wide it will take up 150,000 pixels. How
big 150,000 pixels is is determined by the display.

 

[Travis Newbury]

Do you mean change the width and/or height, so that they're all golden
rectangles?
yes

What if the image is inherently a square? Or inherently a long,
narrow rectangle such as a panoramic landscape photograph?

Well then we have an exception don't we.

 

[dorayme]

I have read quite a few studies on using Fibonacci's golden ratio in
design, music and when displaying images.

http://desktoppub.about.com/od/goldenrectangle/Golden_Ratio_Phi_and_the_Golden
_Rectangle_in_Design.htm

It seems for one reason or another these are more appealing to
humans. So I would take your image sizes and use the golden ratio to
tweak their size.

Oh.. you remind me that I have made a mistake in the 800px high figure
above. I was not meaning to address *anything* to do with aspect ratio -
not recommending even thumbnails to be square - and I should have
explained more.

The 800px high is *too high* and if I am confronted by pictures that
need to be square or even higher than wide, I am quite wary of going
beyond 600px down. When thinking usability and screens, max of either is
important to note and they are different (humans and screens being what
they are).

I better add, it is also OK to supply bigger still but to go into actual
details of file and px size so the punters know what they are in for.
The above, one need not do this for, but bigger, yes *generally*).

Another point while on this subject of offerings of enlargements, is to
be reasonable in the scales offered. I wish I had noted the URL but
yesterday I was looking up Brit penny stamp sites and came across the
most frustrating case. There was a nice stamp I wanted to see bigger
than thumbnail, the offer for bigger was just one and weighing in at the
green corner: 13+ MB! Sometimes one wonders if these website makers had
a common sense bypass at some stage.

As for the aspect ratio, yes this is a fascinating matter. I know it
took me a while to see the beauty in 35mm pics, uncropped. I still feel
it is not a *natural beauty* but is loveable for those of us steeped in
the history and technology of these cameras.

On your point, I could not get used to a Hassleblad camera I once
bought, one being the natural format. I bought a 6 x 4.5 back, toot
sweet <g>. Now this format had a natural beauty that 35mm lacked.

 

[dorayme]

72dpi tells the
printing mechanism "space your dots evenly so that 72 of them fill one
inch. (or 5184 of them fill one square inch)"

If anyone is interested, I have a printer design that prints the dots
unevenly, it averages what the user wants but is what I call "random
entropy aware" (the scientific name helps flog the design to gullible
manufacturers). If anyone here at alt.html wants a special deal (open
only for one week - so hurry!), please send details and $US20 per share.

 

[dorayme]

On Oct 16, 8:55 am, (e-mail address removed) (Doug Miller) wrote: ....

Well then we have an exception don't we.

You killer, Travis! <g>

 

[dorayme]

If anyone is interested, I have a printer design that prints the dots
unevenly, it averages what the user wants but is what I call "random
entropy aware" (the scientific name helps flog the design to gullible
manufacturers). If anyone here at alt.html wants a special deal (open
only for one week - so hurry!), please send details and $US20 per share.

So, if I sent you a pic of me and you printed it with this design, my
left eye would wind up in my mouth and my right ear would be on my chin?[/QUOTE]

No, no, no... it is not my "Silly Printer" design, that one I don't try
to flog any more, it got me a severe beating by a horrid bad tempered
company exec when I approached him with it.

In my REA, which I admit I am having slight difficulties financing (if
you don't mind me saying, you chaps are pretty tight with your dough)
the *order* of the dots remains as in the digital file, it just spaces
them tighter or looser while ensuring that every bunch of 72 of them is
within an inch. So, if 72 of them in an o so 20th Century printer is
part of a nose, it is still part of a nose and not an ear in this
postmodernist printer. It is just that noses and mouths and things look
sort of interestingly splotchy-abstract at times, realistic at other
times.

What the average resolution is over a square inch does not predict the
resolution of the parts of the inch.

Wanna pay now or think about it some more, you have a week and THE OFFER
ENDS!