I wasn't going to read this post, because I don't have an Epson printer
(well, I do, but it doesn't do color). I'm glad I did, because the intro was
both funny and informative. The rest was *very* informative, and I'm
archiving it. Even if I don't print a lot, this makes such crystal-clear
sense that I need to keep it. Thanks, Roger.
Best regards--LRA
>From: RogerMillerPhoto@aol.com
>Reply-To: filmscanners@halftone.co.uk
>To: filmscanners@halftone.co.uk
>Subject: Re: filmscanners: Figuring out size & resolution
>Date: Sat, 7 Jul 2001 17:54:12 EDT
>
>Rick, I'm not sure exactly what you mean by "density," but not knowing what
>the question is has never stopped me from giving an answer before. I'll
>assume that density means the number of dots per inch (dpi) that you send
>to
>the printer. There's another value that has to do with how many dpi the
>printer actually prints on paper, such as 1440 dpi. But that value is
>printer specific. My Epson 2000P doesn't even let me set that value. It
>gives me a choice of printing at "photo quality" speed or "high speed" and
>adjusts the number of "dots" on the paper accordingly. My recommendation
>is
>that you tell your printer to print on paper at the highest number of dots
>per inch your printer is capable of (1440?) so as to get the best "photo
>quality" and that you send the image to the printer at 300 dpi. I'd also
>recommend you check out <A HREF="www.scantips.com">www.scantips.com</A> for
>related information.
>
>Most printers are happy if they are fed data at a "density" of 300 dpi.
>With
>less than that the print quality suffers. With more dpi than that, it's
>just
>a waste of good pixels and the print quality isn't any better than if 300
>dpi
>were used. I've read on this list that some of the cheaper printers don't
>improve past about 240 dpi and there are some that don't stop improving
>until
>you pass 360 dpi. But a good rule of thumb is to use something close to
>300
>dpi.
>
>For example, assume that you scan a 35 mm slide with a scanner that scans
>at
>4000 dpi. If the slide is 1x1.5 inches in size (it's a bit smaller due to
>the mount, etc., but this makes the math easier), then you'll have an image
>that's 4000x6000 pixels. The maximum size of print you can make from that
>image is found by dividing the 4000 and 6000 pixel dimensions by 300 (the
>dpi
>you need to send to your printer). And the answer is: 13.33x20.00 inches.
>So that's the largest print that you can get and still have at least 300
>dpi
>worth of data to send to your printer. If you try to print something
>bigger
>than that, you'll be forced to send less than 300 dpi to the printer and
>the
>print quality will go down. But, suppose you want to an 8x12 print.
>Divide
>4000 by 8 (or 6000 by 12) and you find that you'll be sending 500 dpi to
>the
>printer. That's more dpi than you really need, but it won't hurt anything.
>(I've heard on this list that using more dpi than necessary uses more ink,
>but I don't think that's true. Maybe someone on the list can enlighten
>me.)
>You can do your calculations in reverse, also. For example, if you want to
>make an 11x14, then multiply each of those numbers by 300 and you'll find
>that you need an image that's at least 3300x4200 pixels in size. So if you
>have a 4000x6000 pixel image, then you've got more than enough pixels for a
>good print. In fact, you might want to "throw away" some of the unneeded
>pixels if you want to save a copy of the print on your hard drive since the
>file size would be smaller. To do that you resize the 4000 dpi, 4000x6000
>pixels, 1x1.5 inch original image so that it becomes 300 dpi, 3300x4200
>pixels, and 8x12 inches. Remember, though, that once you resize an image
>in
>such a manner that pixels are thrown away, you can't resize back up to an
>image with the original number of pixels.
>
>I hope I answered your question. If not, restate it and I, or someone
>else,
>will try again.
>
>In a message dated 7/7/2001 12:06:08 PM Pacific Daylight Time,
>rickdecker@hawaii.rr.com writes:
>
>
> > I just bought a Epson 1270SU.
> >
> > Is there a formula for picking density and output size based on input
> > size and projected print size.
> >
> > I scan 6x7 and will print either 8x10 or 11x14
> >
> > And I scan 35mm and will print either 8x(10/12) or 11x(14/16)
> >
> > If I specify my output size, how do I decide what density to pick?
> >
> > Thanks
> >
> > Rick Decker
> >
>
>
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