Setting for Scanning 35mm negatives -- output resolution

<p>My scanner says that its' maximum output resolution is 4000 pixels/inch. Why would I need that much resolution if all I want is to print up to 8 x 12 or send a picture in an email or post a picture on the web? Am I missing something here? Don't all I need is about 375 pixels and inch? That doesn't sound correct.</p>

<p>If you want to post on the web, you just scan it at the final rez you want to see the image at.<br>

For prints in general you would want to print at a native scan rez, IE if you are printing at 240 dpi 8x10 the you would want a file roughly about 2000x3000 or scan at about 2000 dpi.<br>

More detail and more options though if you scan at 4000 dpi and archive. You could print at 18" x 24" on a lightjet at 204 dpi or reduce to any size you want.<br>

You can also send it to your printer at 4000 dpi and let the printer rip the size down to 8x10 or whatever it needs.</p>

<p>always scan at the highest possible rez (if it's a film scanner.....flatbeds highest rez is not always as stated, so lower rez's may do just as well). The idea is to scan once in highest rez, and then do all your editting in that high rez...that way the least possible image degredation occurs....and reduce the rez to your desired final output as required. Down rezzing does little to no image degredation.....up rezzing is plagued with degredation and/or special software to accomodate.</p>

<p>The confusion here is that the DPI of the scanner refers to dots per inch of film. Suppose a 35mm film frame is 1" x 1.5" and you scan at 4000 DPI, that gives you a 4000x6000 image. If you print 8x12 the print is at 500 DPI. This is still a lot, you could set the scanner at 3200 DPI and not see a difference, but if you wanted to print at 24x36 you'd appreciate the high resolution.</p>

<p>well, Andrew, actually DPI is wrong for a scanner, it should be PPI.....Pixels Per Inch. DPI....Dots Per Inch.....is for printer rez. There are no dots in scanning or even in monitor rez, they are pixels.</p>

<p>For an 8x12 inch print if you are using a dedicated film scanner like a Coolscan I would scan at 4000dpi to get the most out of the film and then downsize and sharpen your image later. For email/web you barely need any resolution but I'd rather scan once and resize than scan three times for different purposes and color correct each scan.</p>

<p>Of course I know that, Thomas. But take one issue at a time. I could be a pedantic snot about PPI and DPI or I could help that OP understand scanner resolution.</p>

<p>I have had very good luck scanning at maximum resolution, saving as a TIF and then editing. I can save multiple times without degrading the image. Then, I can reduce the size to whatever I need. </p>

<p>If you have the file printed, the equipment will downsize, or upsize, automatically. </p>

<p>>>My scanner says that its' maximum output resolution is 4000 pixels/inch. Why would I need that much resolution if all I want is to print up to 8 x 12 or send a picture in an email or post a picture on the web? Am I missing something here? Don't all I need is about 375 pixels and inch? That doesn't sound correct.</p>

<p>It is correct.<br>

4000 dpi is the "input" resolution, at the film size, about 1.4x0.9 inches. So this scan creates about<br>

(1.4 inches x 4000 dpi) x (0.9 inches x 4000 dpi) = 5600 x 3600 pixels of image size.<br>

<br />Those same exact unaltered 5600x4000 pixels, when scaled to be spaced 300 dpi printed on paper, will cover<br>

5600 pixels /300 dpi =18.6 inches<br>

3600 pixels /300 dpi = 12 inches. THIS is output size, 18x12 inches at 300 dpi. </p>

<p>This is called scaling, to specify a different dpi number to alter the number of inches that the SAME pixels will cover on paper.<br>

<br />The basics are that the ratio of (scanning dpi / printing dpi) = enlargement factor.</p>

<p>If you want to print the image 10 times larger than the film frame, then to have enough pixels do to that, you scan at scanning dpi = 10x the printing dpi.</p>

<p>10x dpi scan prints 10x larger, when at 1/10 the dpi (like 3000 dpi scan, 300 dpi print).</p>

 

<p>There is nothing wrong with using the term "dpi" with scanning at all; that is the industry standard term used for the last 3 decades plus. It was used before Photoshop; before Photo.net; before there was even iso 800 color print films. </p>

<p>Usage of DPI with scanners bothers folks new to scanning. It is used in 1980's DOS wands software; our 1989 35mm slide scanner and all the 100k plus dollars of scanners I have ever owned. It is used with about very scanner ever made on the planet.</p>

<p>It is used on FAX machines; US Patent literature; US Government bids on scanning documents. If I scanned a 4x5" transparency with our 3000 buck 1200 dpi flatbed in 1994 and open the file in Photoshop 2.5; one sees a 4x5 image at 1200 pixel per inch. In that era amateurs could not afford flatbeds; us service bureaus who used them knew that a 1200 dpi setting put out a 1200 ppi image. the conversion is not hard; ie it is one. It is like converting Lbs of BS to Lbs of manure; an old farmer may call theses plies "chips" or "paddies" too! :) </p>

<p>Later on some Photoshop book writers got their panties in a knot over dpi and ppi; they did not even work with scanners the decade before; thus they went on this dumb crusade attacking dpi in scanners as being wrong. </p>

<p>In a way it is like when folks new to film call it analog; it is part of the newbie thing to ignore decades worth of history. Errors like this make folks who have been around awhile question what other gaps they have in their knowledge; or what the purpose is to inject confusion. It sticks out like a carpenter discovering that a 2x4 is not actually 2x4 inches. </p>

<p>Folks scanners have setting in dpi for a reason; it is the term used since the days of early DOS scanners.</p>

<p>If I state that I scanned this image with my Canon FS4000U 35mm slide scanner at a 2000 dpi setting it is totally clear what scan resolution was used. Injecting that it is really 2000 ppi is abit odd; since it is obvious.</p>

<p>To the poor newcomer injecting to use say a 1600 ppi scan setting is odd too; since the software reads in dpi. It just adds<br>

confusion.<br>

There was really none of this injecting (scanners are not in dpi) silly stuff when only pros used scanners; too cute photoshop writers with no sense have injected this silly rubblish; it makes them look inexperienced and small.</p>

<p>I was using a Nikon F3 yesterday shooting shooting some film; somebody said I was using an Antique to shoot Analog. </p>

<p>If dpi has been the established term for scanner resolution for 3 decades; what purpose does injecting newbie terms do but inject confusion? Also what purpose does it do to call film analog?</p>

<p>regardless Kelly.....ppi is for scanning and video display, and dpi is for printing output. To condone the mis-use just "because it's always been done that way" is always wrong.</p>

<p>And personally, once I realized the difference between the two, I finally understood the difference between what to use in scanning and what to use in printing.</p>

<p>>>If dpi has been the established term for scanner resolution for 3 decades; what purpose does injecting newbie terms do but inject confusion?</p>

<p>Exactly. Right on Kelly, thanks. Newbies dont always understand the real world, and just cause more confusion when they shout "Wrong" about 90% of what they see. Laughable, but sad too.</p>

<p>All scanners are rated dpi. There are no ink drops in scanners. dpi means pixels per inch.</p>

<p>JPEG specifications: http://www.w3.org/Graphics/JPEG/jfif3.pdf page 5 says "dpi".<br>

<br />TIFf specifications: http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf page 38 says resolution is "dots", per inch or centimeter</p>

<p>Always was dpi, probably always will be dpi. To have two meanings for dpi is not confusing. If the context is about images, it can only mean pixels per inch. If the context is about printers, it can only mean ink drops per inch. English words are like that.</p>

<p>The one thing that CAN be said to educate newbies is to tell them that we WILL see it both ways, and so it is good if we understand it both ways. Otherwise, we are ignorant, if we cannot understand what we read everywhere.</p>

<p> </p>

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<p>Why would I need that much resolution if all I want is to print up to 8 x 12 or send a picture in an email or post a picture on the web?</p>

 

</blockquote>

<p>Set the resolution to give you 300 pixels of scan, for each inch on print you expect to make.<br>

As you set different resolutions, you should then see a difference in the pixel dimensions displayed, prior to making the scan.<br>

<a href="http://www.scantips.com/">www.scantips.com</a></p>

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<p>Why would I need that much resolution if all I want is to print up to 8 x 12 or send a picture in an email or post a picture on the web?</p>

</blockquote>

<p>Because your time is expensive and disk storage is cheap.</p>

<p>Not only is scanning itself slow, but scanned images invariable require adjustments: everything from color rebalancing, spotting to grain reduction and sharpening. Digitize at the maximum real resolution of your scanner, and it's easy enough to derive all lower resolution products. Digitize to some small target print size, and you'll have to rescan and re-post process for anything larger.</p>