This is a simple nit of a question.  Often, when preparing images to be
uploaded to the Web, we are advised to save them at 72ppi because that is
the resolution of many older monitors.  Along with that advice we are often
also told to restrict our images to a certain size, for example a long
dimension of 600 pixels.  Is there any point in doing both of these resizing
operations?  If I save an image as, for example, a 600x400 pixel image it
will appear at that absolute size on a monitor regardless of whether it is
saved at a resolution of 72ppi or 150ppi!  If the image were to be printed
that, of course, could make a difference but if the only concern is to
properly display the image on other's monitors is there any point to
resizing to both an absolute dimension AND a certain ppi size?
Chuck

"C Wright" <wright9_nojunk@nojunk_mac.com> wrote in message
news:C09DD224.5BFB9%wright9_nojunk@nojunk_mac.com...
> This is a simple nit of a question.  Often, when preparing images to be
> uploaded to the Web, we are advised to save them at 72ppi because that is
> the resolution of many older monitors.  Along with that advice we are
> often
> also told to restrict our images to a certain size, for example a long
> dimension of 600 pixels.  Is there any point in doing both of these
> resizing
> operations?  If I save an image as, for example, a 600x400 pixel image it
> will appear at that absolute size on a monitor regardless of whether it is
> saved at a resolution of 72ppi or 150ppi!  If the image were to be printed
> that, of course, could make a difference but if the only concern is to
> properly display the image on other's monitors is there any point to
> resizing to both an absolute dimension AND a certain ppi size?
> Chuck


Just use the save for web function in Photoshop, put in your dimensions
600x400 or whatever - I don't believe you are even asked for ppi

> C Wright asks ...
>
>if the only concern is to properly display the image on other's
>monitors is there any point to resizing to both an absolute
>dimension AND a certain ppi size?

No, as you say the ppi figure is meaningless for display purposes ...

C Wright wrote:
> This is a simple nit of a question.  Often, when preparing images to be
> uploaded to the Web, we are advised to save them at 72ppi because that is
> the resolution of many older monitors.  Along with that advice we are ofte
n
> also told to restrict our images to a certain size, for example a long
> dimension of 600 pixels.  Is there any point in doing both of these resizi
ng
> operations?  If I save an image as, for example, a 600x400 pixel image it
> will appear at that absolute size on a monitor regardless of whether it is
> saved at a resolution of 72ppi or 150ppi!  If the image were to be printed
> that, of course, could make a difference but if the only concern is to
> properly display the image on other's monitors is there any point to
> resizing to both an absolute dimension AND a certain ppi size?
> Chuck
>

As the others have said, no. The pixel dimensions are all you should
concern yourself with.

--
Comic book sketches and artwork:
http://www.sover.net/~hannigan/edjh.html
Comics art for sale:
http://www.sover.net/~hannigan/batsale.html

In article <C09DD224.5BFB9%wright9_nojunk@nojunk_mac.com>,
C Wright <wright9_nojunk@nojunk_mac.com> wrote:

> This is a simple nit of a question.  Often, when preparing images to be
> uploaded to the Web, we are advised to save them at 72ppi because that is
> the resolution of many older monitors.  Along with that advice we are ofte
n
> also told to restrict our images to a certain size, for example a long
> dimension of 600 pixels.  Is there any point in doing both of these resizi
ng
> operations?  If I save an image as, for example, a 600x400 pixel image it
> will appear at that absolute size on a monitor regardless of whether it is
> saved at a resolution of 72ppi or 150ppi!  If the image were to be printed
> that, of course, could make a difference but if the only concern is to
> properly display the image on other's monitors is there any point to
> resizing to both an absolute dimension AND a certain ppi size?

No.

The people who tell you to save at 72 ppi do not understand resolution.

When an image is displayed in a Web browser, the Web browser strips off
and disregards any ppi information. The only thing--the ONLY thing--that
matters to a browser, any browser, is the total number of pixels. All
Web browsers display an image at one pixel inthe image equals one pixel
on the screen.

A 300x200 pixel image at 72 pixels per inch is absolutely, completely
identical, in all Web browsers and on all platforms, to the same 300x200
pixel image at 96 pixels per inch, the same 300x200 pixel image at 300
pixels per inch, and the same 300x200 pixel image at 3,000,000 pixels
per inch. For Web use, resolution in terms of pixels per inch is
completely irrelevant.

--
Art, photography, shareware, polyamory, literature, kink:
all at http://www.xeromag.com/franklin.html
Nanohazard, Geek shirts, and more: http://www.villaintees.com

On Sat, 27 May 2006 14:53:40 GMT, C Wright
<wright9_nojunk@nojunk_mac.com> wrote:

>This is a simple nit of a question.  Often, when preparing images to be
>uploaded to the Web, we are advised to save them at 72ppi because that is
>the resolution of many older monitors.  Along with that advice we are often
>also told to restrict our images to a certain size, for example a long
>dimension of 600 pixels.

This might help explain things:

http://www.ransen.com/Articles/DPI/Default.htm

and

http://www.ransen.com/Articles/MegaPixels/default.htm


http://www.ransen.com/

In article <kn6j729bb9lc3gip9e67pjmm6c1hje1ie6@4ax.com>,
Owen Ransen <willy@wonker.com> wrote:

> On Sat, 27 May 2006 14:53:40 GMT, C Wright
> <wright9_nojunk@nojunk_mac.com> wrote:
> 
>
> This might help explain things:
>
> http://www.ransen.com/Articles/DPI/Default.htm
>
> and
>
> http://www.ransen.com/Articles/MegaPixels/default.htm
>
>
> http://www.ransen.com/

It is my understanding that the human eye can't distinguish much
above 72 or perhaps 75 dpi, so for images that will be viewed on
a monitor, but not printed, there's no advantage to setting the
resolution above this. For printing, though--and here my understanding
isn't so clear--it appears preferable to set images much higher,
so settings of 600 or more shouldn't be unreasonable. I don't
know if what I said about the human eye extends to printed pages
or not.

On a somewhat related note, if scanning an image to bring into
an image editing program, my instinct is to scan at a very high
resolution, and then have the option to save/print edited versions
at lower resolutions.

Hoping for further clarification here...
Happy computing,
Eric

--
For e-mail replies, please send to "thustar at yahoo dot com."

Eric P. wrote:
> In article <kn6j729bb9lc3gip9e67pjmm6c1hje1ie6@4ax.com>,
>  Owen Ransen <willy@wonker.com> wrote:
> 
>
> It is my understanding that the human eye can't distinguish much
> above 72 or perhaps 75 dpi, so for images that will be viewed on
> a monitor, but not printed, there's no advantage to setting the
> resolution above this.

It's actually ppi, not dpi at this stage. Most monitors now are around
96 ppi, a rule of thumb when setting pixel dimensions for monitor viewing.

> For printing, though--and here my understanding
> isn't so clear--it appears preferable to set images much higher,
> so settings of 600 or more shouldn't be unreasonable. I don't
> know if what I said about the human eye extends to printed pages
> or not.

Most folks are fine with 300 or so ppi for printing, and it's not clear
that more ppi makes a discernable difference in final product, and it
prints much slower. Here's where dpi comes in: Some printers can be set
to print at 360, 720, 1440 etc. dpi, all from the same image. Other
printers may call it HQ, or fine, or medium, or draft, etc.

>
> On a somewhat related note, if scanning an image to bring into
> an image editing program, my instinct is to scan at a very high
> resolution, and then have the option to save/print edited versions
> at lower resolutions.

That instinct is right! Unless you have dozens of images to scan and
they will go only onto a web page....

--
John McWilliams

In article
<ericp06-385ADD.06454128052006@newsclstr02.news.prodigy.com>,
"Eric P." <ericp06@sbcglobal.net> wrote:

> It is my understanding that the human eye can't distinguish much
> above 72 or perhaps 75 dpi, so for images that will be viewed on
> a monitor, but not printed, there's no advantage to setting the
> resolution above this. For printing, though--and here my understanding
> isn't so clear--it appears preferable to set images much higher,
> so settings of 600 or more shouldn't be unreasonable. I don't
> know if what I said about the human eye extends to printed pages
> or not.

This is factually incorrect. The human eye can easily distinguish detail
above 72 pixels per inch.

However, a monitor is a fixed pixel device. It is made up of a grid of
pixels. A monitor who's resolution is set to 72 pixels per inch always
displays all images under all circumstances at 72 pixels per inch,
without exception. A monitor who's resolution is set to 96 pixels per
inch always displays all images at 96 pixels per inch.

--
Art, photography, shareware, polyamory, literature, kink:
all at http://www.xeromag.com/franklin.html
Nanohazard, Geek shirts, and more: http://www.villaintees.com

"tacit" <tacitr@aol.com> wrote in message
news:tacitr-32B6C2.11333328052006@news-server2.tampabay.rr.com...

> [...] A monitor who's resolution is set to 96 pixels per
> inch always displays all images at 96 pixels per inch.

Tacit: Isn't the Apple Cinema Display 120 ppi?