Scanning DPI(resolution)

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Scanning DPI

150
2
20%
300
7
70%
600
1
10%
Other
0
No votes
 
Total votes : 10
dpollitt

Scanning DPI(resolution)

Postby dpollitt » Wed May 23, 2007 10:07 am

What would you recommend as a good resolution to scan photos at for a wedding show?

I'm trying to scan all of the photos first then start to work with producer, and I know that the output characteristics might determine what I need coming in. I'm planning on putting the show on a DVD for a projector(~60inch).

Is 300dpi good enough or should I take the extra time to scan the mostly 4x6's at 600dpi. Thank you!

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Postby briancbb » Wed May 23, 2007 1:35 pm

Welcome to the forum.

I have not voted, but I will, at 300 dpi. Your 6 x 4 at 300 dpi will give you a 1800 x 1200 pixel image this will be adequate unless you intend to zoom in greatly. If this is the case up the resolution of the scan to maintain a picture of the same pixel size at the max zoom. (Hope you get what I mean).

My camera takes 1600 x 1200 images and I find these OK unless I zoom in more than 150%, or there abouts. That's my rational.

Brian

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Postby DickK » Wed May 23, 2007 7:14 pm

Your question is both common and a good one but there's no "one size fits all" answer to your question because it depends heavily on what you are going to do with the resulting scan.

Basically, the scanning resolution will determine image size. If all you want to do is capture the information on a color print, 150ppi is sufficient. A 4x6 print will produce 600x900 pixels. That captures all the information on the print but it may not give you all the pixels you want--as Brian points out. More pixels doesn't mean better but it does mean bigger and more pixels also means you can zoom more before getting visible artifacts. That might be important for your images if you're going to crop them before using them in ProShow or zoom them in ProShow.

Here's an excellent resource for information about scanning and getting the most out of it:
http://www.scantips.com/

The other big variable is the output format you're going to use. If you're making a DVD then the NTSC video output isn't going to improve by throwing more pixels at the problem, they're just going to get thrown away in the rendering process. If the output is an EXE on the other hand, the limit is whatever the screen you're viewing it on can handle so more pixels might be a good thing indeed.

So, let's go back to your situation--scanning color 4x6's for output to a DVD. If you do little or no zooming or cropping in an editor, 150ppi will be all you need. Despite that I'm going to agree with Brian's comment and suggest a 300ppi scan to protect against wanting to do that zoom in ProShow or a major crop in an editor. 300ppi is overkill and produces bigger output files (1200x1800pixels) but unless harddrive space is an issue it provides a hefty safety margin. But there's no reason to go above that for scanning color prints.

One issue to also consider is scan file output format. If you intend to do any editing of the files then I strongly recommend that you use a TIFF or PNG (lossless compression) output. All those nice pixels in the scan will do a lot less for you if you scan to a JPG and go through a couple edit & save cycles -- the image will still be big but it's quality can deteriorate significantly with just a couple cycles in an editor.

Hope that helps not confuses!
Dick
"It is the mark of an educated mind to be able to entertain a thought without accepting it." Aristotle ((PSG, PSE & Fuji HS20 user)) Presentation Impact Blog

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