scanning a photo, what dpi

T
Posted By
Tim923
Jul 24, 2006
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525
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I’d like to scan a photograph, roughly the size of an index card, to put on a webpage, and show good or great detail. Any suggestions on what DPI and percentage I should use?
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R
Roberto
Jul 24, 2006
Most screens are 72dpi.

R

"Tim923" wrote in message
I’d like to scan a photograph, roughly the size of an index card, to put on a webpage, and show good or great detail. Any suggestions on what DPI and percentage I should use?
NS
Nicholas Sherlock
Jul 24, 2006
Tim923 wrote:
I’d like to scan a photograph, roughly the size of an index card, to put on a webpage, and show good or great detail. Any suggestions on what DPI and percentage I should use?

Scan at say 150 DPI, then use Photoshop to resize your picture to your desired final *pixel* dimensions.

Cheers,
Nicholas Sherlock

—
http://www.sherlocksoftware.org
JM
James McNangle
Jul 24, 2006
Tim923 wrote:

I’d like to scan a photograph, roughly the size of an index card, to put on a webpage, and show good or great detail. Any suggestions on what DPI and percentage I should use?

The first question you must ask yourself is what size you want the image to be on your web page. There is no RIGHT ANSWER to this question, as you don’t know what resolution monitor the viewer will have, and what size he will have his window set to. If it is for an illustration to an article, or the like, I usually make my images 300 to 400 pixels wide, but if it is a high-quality photo, with lots of details, and I am publishing it as a photo to be enjoyed, I might go up to 800 pixels.

Then, if you know that you will never want to use the scanned photo for any other purpose, you can measure it, and calculate what resolution you need to get the image of the correct size. For example, if it is 6 in. wide, and you want an image 600 pixels wide, scan at 100 pixels per inch.

However, if it is a remotely interesting picture, I would always scan at 300 pixels per inch. Unless it is a really high-quality print this will catch all the detail there is to be found in it. It will also provide some margin, in case I want to crop the image to improve the composition. Then I would optimise the composition and colour balance, and save it again full size. Finally I would reduce the size of the image to whatever size I had decided to use on the web page (with rescanning enabled), and Save it for Web under another name.

James McNangle
MV
Matti Vuori
Jul 24, 2006
"Hebee Jeebes" wrote in news:44c4674a$0$34561 $:
Most screens are 72dpi.

No. Hardly any screens are 72 ppi. Most are around 96 ppi.

—
Matti Vuori, <http://sivut.koti.soon.fi/mvuori/index-e.htm>
T
Tim923
Jul 24, 2006
On Mon, 24 Jul 2006 17:38:25 +1000, James McNangle
wrote:

Tim923 wrote:

I’d like to scan a photograph, roughly the size of an index card, to put on a webpage, and show good or great detail. Any suggestions on what DPI and percentage I should use?

The first question you must ask yourself is what size you want the image to be on your web page. There is no RIGHT ANSWER to this question, as you don’t know what resolution monitor the viewer will have, and what size he will have his window set to. If it is for an illustration to an article, or the like, I usually make my images 300 to 400 pixels wide, but if it is a high-quality photo, with lots of details, and I am publishing it as a photo to be enjoyed, I might go up to 800 pixels.

I think I want a high quality scan that maybe they can download and a smaller pic for the web site. 300dpi should be enough?
JM
James McNangle
Jul 25, 2006
Matti Vuori wrote:

No. Hardly any screens are 72 ppi. Most are around 96 ppi.

For what it’s worth, the two screens in front of me have resolutions of 78 PPI and 87 PPI. But the only real practical significance of this figure is that if your screen has a lower resolution per inch you will sit slightly further away from it than you would if it had a higher resolution. When you are choosing a screen resolution is one of the factors which will influence your choice, but once you have bought it you will never think about it again.

The important figure is the total number of pixels — 1024 by 768 in the first case, and 1280 by 1024 in the second. The bigger screen is my primary screen, but, even with it, my actual working window is seldom more than 1024 pixels wide. The extra width accommodates the clutter which programs like Photoshop have around the edges, and allows me to have several windows open once.

Photoshop always specifies the resolution of the image you are working on, but this figure has no significance whatsoever until you print the image, at which stage it determines the size of the print. Again the important figure is the total number of pixels in the image. A high-quality 35mm negative will have a substantially higher resolution than a full plate negative, but the latter will have a higher number of equivalent pixels, and this is why you can get a bigger print from the full plate negative for the same resolution.

James McNangle
JM
James McNangle
Jul 26, 2006
Tim923 wrote:

On Mon, 24 Jul 2006 17:38:25 +1000, James McNangle
wrote:

Tim923 wrote:

I’d like to scan a photograph, roughly the size of an index card, to put on a webpage, and show good or great detail. Any suggestions on what DPI and percentage I should use?
….
I think I want a high quality scan that maybe they can download and a smaller pic for the web site. 300dpi should be enough?

300 dpi should be fine. It would be an exceptional photo that would be sharp enough to justify scanning at any higher resolution. And if, as I guess, the photo is about 4 in. by 6 in., this will give you an image 1200 by 1800, which is as big as anybody would want to download.

James McNangle
BW
Bob Williams
Aug 2, 2006
Tim923 wrote:
I’d like to scan a photograph, roughly the size of an index card, to put on a webpage, and show good or great detail. Any suggestions on what DPI and percentage I should use?

If your photograph is 4" x 6" and you scan at 100 dpi (really ppi) your image size would be 400 x 600 pixels. Good for folks using Web TV or those whose screen resolution is set to 600 x 800 pixels. Scanning at 150 ppi would produce an image size of 600 x 900 pixels. That is probably a pretty good compromise. It will look good, without scrolling, on monitors set at 768 x 1024 pixels. It will require very little scrolling on monitors set for 600 x 800 pixels.
That covers well over 50% of monitors in use today.
Bob Williams

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