Resolution of website images – does it matter?

I’ve been designing websites for several years. At some point early on, I’d heard (from what I believed to be a reliable source) that website images should have a resolution of 72 dpi. So that’s what I’ve been doing.

Now, several tens of thousands of images later, I’m questioning that. Not really knowing a lot about this, it seems to me that as far as a browser is concerned, 500 pixels is 500 pixels, regardless of the resolution.

Am I wrong about this?

Nope. You’re spot on.
The problem with your theory is this:
500 x 500 pixels at 72 ppi (pixels per inch) (dpi, or dots per inch, is for print) gives you an image that is nearly 7 x 7 inches.
500 x 500 pixels at 300 ppi gives you an image that is about 1 5/8 inches square.
Both will load to the web site at the same speed. Both will be of the same quality, since monitors don’t display greater than 72 ppi anyways. I suspect people would prefer to look at the larger image though.

Keith.

In article ,
Arcfus Barcwinkle wrote:

Now, several tens of thousands of images later, I’m questioning that. Not really knowing a lot about this, it seems to me that as far as a browser is concerned, 500 pixels is 500 pixels, regardless of the resolution.

Am I wrong about this?

No, you’re exactly right. A 500 by 500 pixel image will display the same way in a browser regardless of whether it’s 72 pixels per inch, 300 pixels per inch, or 3,000,000 pixels per inch–the browser discards the resolution information and displays it at the resolution of the monitor.

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html

In article <Ar2he.43367$>,
"_+arrooke" wrote:

Both will load to the web site at the same speed. Both will be of the same quality, since monitors don’t display greater than 72 ppi anyways. I suspect people would prefer to look at the larger image though.

On a Web browser, they will display at exactly the same size; the size in inches only matters *for print*, not for display on the screen.

A 500 by 500 pixel image will display exactly the same way at exactly the same size in a browser no matter what resolution it is.

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html

On Fri, 13 May 2005 09:49:45 -0400, Arcfus Barcwinkle
wrote:

I’ve been designing websites for several years. At some point early on, I’d heard (from what I believed to be a reliable source) that website images should have a resolution of 72 dpi. So that’s what I’ve been doing.

DPI specification only makes sense when printing.

Now, several tens of thousands of images later, I’m questioning that. Not really knowing a lot about this, it seems to me that as far as a browser is concerned, 500 pixels is 500 pixels, regardless of the resolution.

Am I wrong about this?

No, dead right, see:

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

Both will load to the web site at the same speed. Both will be of the

same

quality, since monitors don’t display greater than 72 ppi anyways. I suspect people would prefer to look at the larger image though.

On a Web browser, they will display at exactly the same size; the size in inches only matters *for print*, not for display on the screen.
A 500 by 500 pixel image will display exactly the same way at exactly the same size in a browser no matter what resolution it is.

Ahh! Yes of course. Would it not take longer to load though, since the file would be larger?

"_+arrooke" wrote in message

[…] since monitors don’t display greater than 72 ppi anyways.

Really? What’s with these 96ppi and 110ppi screens?

"_+arrooke" wrote in message

Ahh! Yes of course. Would it not take longer to load though, since the file
would be larger?

Pixels are pixels. It doesn’t matter what ppi you think they are.

On Fri, 13 May 2005 14:31:33 GMT, Tacit wrote:

Am I wrong about this?

No, you’re exactly right.

Ok, now I want the accumulated month of my life back that I’ve spent adjusting the resolution. :-/

Thanks everyone!

_+arrooke wrote:

On a Web browser, they will display at exactly the same size; the size in inches only matters *for print*, not for display on the screen.
A 500 by 500 pixel image will display exactly the same way at exactly the same size in a browser no matter what resolution it is.

Ahh! Yes of course. Would it not take longer to load though, since the file would be larger?

That’s a common misunderstanding. The file is NOT larger. The resolution only refers to the size the pixels are printed, nothing else. You can compare it with a text file. The size of the file is determined by the number of characters in the text, not by the font size.

—
Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.nl/

Ahh! Yes of course. Would it not take longer to load though, since the

file

would be larger?

That’s a common misunderstanding. The file is NOT larger. The resolution only refers to the size the pixels are printed, nothing else. You can compare it with a text file. The size of the file is determined by the number of characters in the text, not by the font size.
—
Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.nl/

But a 3 x 3 inch file at 300 ppi is larger than a 3 x 3 inch file at 72 ppi – no?. Speaking in kb’s. So would that not take longer to load to a web site?

Arcfus Barcwinkle wrote:

At some point early on, I’d heard (from what I believed to be a reliable source) that website images should have a
resolution of 72 dpi.

See: <http://www.scantips.com/no72dpi.html>.

—
Regards
Madsen

On Fri, 13 May 2005 14:32:46 GMT, Tacit wrote:

A 500 by 500 pixel image will display exactly the same way at exactly the same size in a browser no matter what resolution it is.

But be sure you (or some lame "easy" software) don’t add inappropriate size tags to your 500×500 file:
<IMG SRC="TEST500x500.JPG" ALT="Wasted Download Time" WIDTH=125 HEIGHT=125 VSPACE=18>

Then it will display tiny but take as long to download as if it showed full size. Every now and then I find a 3 or 4 MP photo displayed as a tiny page element.

Loren

"Loren Amelang" wrote in message

On Fri, 13 May 2005 14:32:46 GMT, Tacit wrote:

A 500 by 500 pixel image will display exactly the same way at exactly the same size in a browser no matter what resolution it is.

But be sure you (or some lame "easy" software) don’t add inappropriate size tags to your 500×500 file:
<IMG SRC="TEST500x500.JPG" ALT="Wasted Download Time" WIDTH=125 HEIGHT=125 VSPACE=18>

Then it will display tiny but take as long to download as if it showed full size. Every now and then I find a 3 or 4 MP photo displayed as a tiny page element.

OTOH you see things like this: http://elearning.winona.edu/ald1/flag.htm

In article <7G6he.46050$>,
"_+arrooke" wrote:

<snip>

But a 3 x 3 inch file at 300 ppi is larger than a 3 x 3 inch file at 72 ppi – no?. Speaking in kb’s. So would that not take longer to load to a web site?

Of course, but the PPI value isn’t the important part, rather it’s the pixel dimensions. A 900×900-pixel image will be more than seventeen times as large (and therefore that much slower to load) as a 216×216-pixel one. OTOH a 300-ppi image 0.72" square will be exactly the same size as a 72-ppi image 3" square, as each contains 216×216 samples.

—
Odysseus

_+arrooke wrote:

That’s a common misunderstanding. The file is NOT larger. The resolution only refers to the size the pixels are printed, nothing else. You can compare it with a text file. The size of the file is determined by the number of characters in the text, not by the font size.
—
Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.nl/

But a 3 x 3 inch file at 300 ppi is larger than a 3 x 3 inch file at 72 ppi – no?. Speaking in kb’s. So would that not take longer to load to a web site?

Yes, a 3 x 3 *INCH* image is bigger if it’s 300 ppi, but a 300 x 300 *PIXELS* image is not. We are talking about pixels, not inches.

—
Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.nl/

In article <sg4he.41858$>,
"_+arrooke" wrote:

Ahh! Yes of course. Would it not take longer to load though, since the file would be larger?

No. A 500 by 500 pixel image at 72 pixls per inch is the same size as a 500 by 500 pixel image at a million pixels per inch. The only thing that matters to image size is the total number of pixels.

If you make a scan of an object, and you make the scan at 300 pixels per inch, the file will be bigger than the same scan made at 72 pixels per inch because there are more pixels.

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html

In article <7G6he.46050$>,
"_+arrooke" wrote:

But a 3 x 3 inch file at 300 ppi is larger than a 3 x 3 inch file at 72 ppi – no?. Speaking in kb’s. So would that not take longer to load to a web site?

Yes, it is.

But on a Web page, we are talking about a 500 pixel by 500 pixel image, bot a 3 inch by 3 inch image. Remember, "inches" only matters when the file is printed out!

Let us say you have two images, one is 500 by 500 pixels at 100 pixels per inch and one is 500 by 500 pixels at 250 pixels per inch.

A Web browser will display them both the same. A Web browser will show them both at the same size. Both files will be the same file size. if you print them, though, one is 5 inches by 5 inches and one is two inches by two inches.

But the Web browser chops off the "pixels per inch" part. To a Web browser, they are 500 pixels by 500 pixels, period–no "pixels per inch."

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html

On Fri, 13 May 2005 10:02:13 -0400, "_+arrooke" wrote:

Nope. You’re spot on.
The problem with your theory is this:
500 x 500 pixels at 72 ppi (pixels per inch) (dpi, or dots per inch, is for print) gives you an image that is nearly 7 x 7 inches.
500 x 500 pixels at 300 ppi gives you an image that is about 1 5/8 inches square.

And you’re correct up to here when you say:

Both will load to the web site at the same speed. Both will be of the same quality, since monitors don’t display greater than 72 ppi anyways.

I don’t know of any monitor produced nowadays, or for the last few years that’s been limited to 72 ppi. Mine is running at 96 ppi. It doesn’t change the facts, but this is something I keep seeing people saying, that hasn’t been true for years.

—

Hecate – The Real One

Fashion: Buying things you don’t need, with money
you don’t have, to impress people you don’t like…

Ahh! Yes of course. Would it not take longer to load though, since the

file

would be larger?

No. A 500 by 500 pixel image at 72 pixls per inch is the same size as a 500 by 500 pixel image at a million pixels per inch. The only thing that matters to image size is the total number of pixels.

If you make a scan of an object, and you make the scan at 300 pixels per inch, the file will be bigger than the same scan made at 72 pixels per inch because there are more pixels.

Ok that is understood, strictly speaking pixels. But I think one must still consider inches because the 300 pixel image will appear so much smaller than the 72. Therefore in reality, it does matter that the file be converted to 72 ppi in order to maintain the image dimension and loading time. Technically; 500 pixels is 500 pixels. But not necessarily practical – right?
K.

I don’t know of any monitor produced nowadays, or for the last few years that’s been limited to 72 ppi. Mine is running at 96 ppi. It doesn’t change the facts, but this is something I keep seeing people saying, that hasn’t been true for years.

Hecate – The Real One

That’s for another thread 🙂

On Fri, 13 May 2005 19:03:18 -0400, "_+arrooke" wrote:

Ahh! Yes of course. Would it not take longer to load though, since the

file

would be larger?

No. A 500 by 500 pixel image at 72 pixls per inch is the same size as a 500 by 500 pixel image at a million pixels per inch. The only thing that matters to image size is the total number of pixels.

If you make a scan of an object, and you make the scan at 300 pixels per inch, the file will be bigger than the same scan made at 72 pixels per inch because there are more pixels.

Ok that is understood, strictly speaking pixels. But I think one must still consider inches because the 300 pixel image will appear so much smaller than the 72. Therefore in reality, it does matter that the file be converted to 72 ppi in order to maintain the image dimension and loading time. Technically; 500 pixels is 500 pixels. But not necessarily practical – right?

A 300×300 pixel image has 90,000 pixels and will appear, on your WEB page bigger than a 72×72 pixel image (which has 5,182 pixels).

Inches have nothing to do with screen/web image size.

_+arrooke wrote:

Ok that is understood, strictly speaking pixels. But I think one must still consider inches because the 300 pixel image will appear so much smaller than the 72. Therefore in reality, it does matter that the file be converted to 72 ppi in order to maintain the image dimension and loading time. Technically; 500 pixels is 500 pixels. But not necessarily practical – right?

Wrong. A 500 x 500 pixel image will always display at the same size, namely 500 x 500 pixels. The browser doesn’t know about ppi, so it will not display a 500×500 pixels @ 300 ppi image differently than a 500×500 pixels @ 72 ppi image. It will also not load it slower, because the file size is the same as well. IT DOES NOT MATTER, period.

—
Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.nl/

In article <Qmahe.42193$>,
"_+arrooke" wrote:

Ok that is understood, strictly speaking pixels. But I think one must still consider inches because the 300 pixel image will appear so much smaller than the 72. Therefore in reality, it does matter that the file be converted to 72 ppi in order to maintain the image dimension and loading time. Technically; 500 pixels is 500 pixels. But not necessarily practical – right?

No.

A 300 pixel per inch image that is 500 pixels by 500 pixels will appear identical, at the same size, as a 500 pixel by 500 pixel image at 72 pixels per inch on the Web. Web browsers do not even look at the pixels per inch; only at the total number of pixels, nothing else. Try it!

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html

On Fri, 13 May 2005 19:06:10 -0400, "_+arrooke" wrote:

I don’t know of any monitor produced nowadays, or for the last few years that’s been limited to 72 ppi. Mine is running at 96 ppi. It doesn’t change the facts, but this is something I keep seeing people saying, that hasn’t been true for years.

Hecate – The Real One

That’s for another thread 🙂

<g>

—

Hecate – The Real One

Fashion: Buying things you don’t need, with money
you don’t have, to impress people you don’t like…

"Owen Ransen" wrote in message

On Fri, 13 May 2005 09:49:45 -0400, Arcfus Barcwinkle
wrote:

I’ve been designing websites for several years. At some point early on, I’d heard (from what I believed to be a reliable source) that website images should have a resolution of 72 dpi. So that’s what I’ve been doing.

DPI specification only makes sense when printing.

I think I read somewhere it is used in email too (Outlook automatically displays it in te email body based on dpi?) but not sure if that is actually true though…