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Re: another possible factor in exposing plate s

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  • Marnie Powers
    Brain- I m not a digital wiz by far. A designer friend of mine advised that I try scanning at really high resolution, and advised that it wouldn t hurt me.
    Message 1 of 7 , Jan 9, 2002
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      Brain-

      I'm not a digital wiz by far. A designer friend of mine advised that I try
      scanning at really high resolution, and advised that it wouldn't hurt
      me. Others have told me that it's not smart, and that I should stick by
      the output lpi x 2 = viable dpi for scanning. Just trying to do what I
      can to see what gives me the best results. I have had the polymer
      plates hold better than 150 lpi in intaglio printing, so I'm playing
      around, maybe not in a very educated manner... thus, I'm looking for
      help. I appreciate your feedback.

      Marnie
      Marnie Powers-Torrey
      Studio Manager
      Book Arts Program
      J.Willard Marriott Library
      (801)585-9191
    • Katie Harper
      Brian: The confusion comes between the terms dpi which refers to dots per inch --or more correctly, but rarely used, ppi pixels per inch--which refer to
      Message 2 of 7 , Jan 9, 2002
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        Brian:

        The confusion comes between the terms "dpi" which refers to "dots per inch"
        --or more correctly, but rarely used, "ppi" pixels per inch--which refer to
        input and digitizing resolution, and "lpi" meaning "lines per inch" which
        refers to output dots of a halftone screen. When a printer says that her
        press will do a 65 or 85 or 100 line halftone, she is referring to the dot
        size in the halftone, which is a series of dots that simulate grays in
        printing. Laser printers do this, too, and also ink jets, although the ink
        jets do it in such a way as to make the dots less visible. If you take any
        printed photograph and view it under a magnifying glass, you will see these
        dots. Now, in the digital world, you can, somewhat crudely, think of these
        halftone dots as being made up of pixels. So the dot, tiny as it might be,
        has even tinier components. If you render an 85-line halftone on a 300 dpi
        printer and compare it to an 85-line halftone rendered on a 1200 dpi
        printer, the 1200 dpi printer output will appear sharper, crisper and with
        better tonal rendition. If you look at both through a magnifier, you will
        see that the dots are the same size, but the 1200 dpi dot is finer and
        crisper. You probably won't notice this difference unless you view it close
        up.

        Confusing? You bet! And to make it even worse, you'd think that higher dpi
        is always better, but not! Just as a halftone screen that is too fine will
        not print well on press, so an image scanned at too high a resolution will
        cause problems in the digital world. To render the best halftone screens,
        it's best to scan an image at 1.5-2x the output lines per inch, but no
        higher than 2x. Anything over that will be not improve image quality, but
        will only make file sizes bigger. For example, if you are using a 300 dpi
        laser printer as your final output, the halftone dots will max out at about
        60 lines per inch, or lpi. 10 x 2 = 120 dots per inch or dpi, so if you scan
        at 120 dpi, your image will be as good as possible. With high resolution
        output, such as on a Linotronic or other imagesetters, the halftone dots can
        be much finer so resolution can be higher. It's best to ask your service
        bureau what settings they recommend. All this goes for images used at 100
        percent. If you enlarge the image, you must accordingly up the scanning
        resolution at scanning time because as the image is enlarged on the
        computer, the resolution drops proportionately.

        Still with us? OK. Now remember: this is for photographs. For line
        art--artwork that has no grays but only black or white--there are no
        halftones created, so you always want to scan at the highest resolution
        possible. Even "interpolated" resolution, which is a way of fudging to get
        higher resolution than is possible in reality, will sometimes improve line
        art.


        If you have any hair left, you can check out that website that Gerald
        recommended. http://halftones.info/
        It's very informative.

        Katie Harper
        Ars Brevis Press
        Cincinnati, OH
        513-233-9588

        Remember: Book arts will save the world!



        > From: Brian Molanphy <bmolanphy@...>
        > Reply-To: PPLetterpress@yahoogroups.com
        > Date: Wed, 9 Jan 2002 14:06:29 -0700
        > To: "'PPLetterpress@yahoogroups.com'" <PPLetterpress@yahoogroups.com>
        > Subject: RE: [PPLetterpress] Re: another possible factor in exposing plate s
        >
        > marnie wrote in part:
        >
        >
        >
        >> How I make the negative:
        >>
        >> Scan a 35mm slide or negative at @1200 dpi.
        >>
        >> Maybe the dot gain is just too great on the letterpess. Or maybe when
        >> the dots get too small, the relief in the plate is not substantial enough.
        >>
        >> I've been able to do very high resolution/low contrast/high detail
        >> work with photopolymer plates printed intaglio, that I keep wanting
        >> the same to be possible with letterpress.
        >>
        >> I'd very much appreciate your (or anyone else's) feedback on how I'm
        >> dealing with these chanllenges...
        >>
        >>
        >>
        >>
        >>
        > marnie and list,
        >
        > first of all, please correct me if i am spreading misinformation. my
        > understanding is that letterpress polymer plates tolerate about 150 lpi or
        > 300 dpi. why no more than that, i dunno. what use is it to scan at 1200 dpi,
        > if the plate won't print more detail than 300 dpi ?
        >
        > brian
        >
        >
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        >
      • bielerpr
        Katie Harper wrote ... Dear Katie Just a bit to add to this. Most of my work is fixing up badly printed or badly preserved images from the past, type
        Message 3 of 7 , Jan 9, 2002
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          Katie Harper wrote

          > Still with us? OK. Now remember: this is for photographs. For line
          > art--artwork that has no grays but only black or white--there are no
          > halftones created, so you always want to scan at the highest resolution
          > possible. Even "interpolated" resolution, which is a way of fudging to get
          > higher resolution than is possible in reality, will sometimes improve line
          > art.

          Dear Katie

          Just a bit to add to this. Most of my work is fixing up badly printed
          or badly preserved images from the past, type specimens, copper or
          steel or wood engravings, illuminated manuscript work, etc. When I am
          scanning for line art reproduction, I always scan in grayscale at the
          highest resolution I can. While a pain in the butt to work with, re
          memory capacity limitations, this gives me a lot more flexibility in
          refinement. You can pop this up once (there is a term for this?) at
          2x but that is about the effective limit, and this should be done
          before you start working with the image. Final output for b/w line
          art (as opposed to halftone) must be at 1200 dpi (minimum) to prevent
          bitmapping (for generating a film negative from a Linotronic).

          Nice response by the way

          Gerald
        • Brian Molanphy
          katie wrote, in part: If you render an 85-line halftone on a 300 dpi ... i get this, basically. but if polymer plates have a limit of about 150 lpi or 300
          Message 4 of 7 , Jan 9, 2002
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            katie wrote, in part:

            'If you render an 85-line halftone on a 300 dpi
            > printer and compare it to an 85-line halftone rendered on a 1200 dpi
            > printer, the 1200 dpi printer output will appear sharper, crisper and with
            > better tonal rendition. If you look at both through a magnifier, you will
            > see that the dots are the same size, but the 1200 dpi dot is finer and
            > crisper.'
            >
            i get this, basically. but if polymer plates have a 'limit' of about
            150 lpi or 300 dpi, what use is the 1200 dpi file ? the file, or the
            laserprint, may have more detail, but will that detail show up on a polymer
            plate? this question may be more meaniful if, for example, one is committing
            the heresy that i do, which is to generate negatives on my 600 dpi laser
            printer.

            brian
          • Katie Harper
            Brian: I guess I don t quite get what you are saying about the limit of about 150 lpi or 300 dpi ... is this something you have read somewhere, some kind of
            Message 5 of 7 , Jan 9, 2002
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              Brian: I guess I don't quite get what you are saying about the "limit of
              about 150 lpi or 300 dpi"... is this something you have read somewhere, some
              kind of specification? I'm sure that photopolymer probably does have a limit
              as to how small a speck it can hold (ie, how fine a halftone dot), but I'm
              pretty sure it is capable of holding much finer detail than most
              letterpresses can print, so the limitation you speak of is not from the
              plate but from the press. In any case, I cannot see how a polymer plate can
              be limited by 300 dpi, since the plate is analog and the term "dpi" refers
              to the digital world.

              And yes, the difference between output from a 600 dpi output device and a
              1200 dpi or larger resolution output device will show, but whether or not
              that difference matters depends on a)what you are printing, b)what you are
              printing on, c) what press you are using and d) what ink. There are probably
              other factors including temperature, roller condition, what the printer has
              for breakfast, and on and on... But it mainly depends on what is acceptable
              quality for the printer or the client. What works for a daily newspaper
              won't be considered acceptable for a slick magazine or a coffee table book
              printed in Italy. One plate may look like royal doo-doo on one type of paper
              and swell on another. For my own work, I tend to try to get the best
              possible image from a plate, so that all the other factors which will
              whittle down the quality have to start from a higher place. Having said
              that, I will add there are times when a home-made neg will work and times
              when it won't. Just as there are times when taking an exposed piece of film
              and scratching a drawing on it will make a great negative, and times when I
              need a careful rendering of an original or a computer file. I'm talking
              images here. With type, I take no chances and get the best quality output
              and plates I can.

              Katie Harper
              Ars Brevis Press
              Cincinnati, OH
              513-233-9588

              Remember: Book arts will save the world!



              > From: Brian Molanphy <bmolanphy@...>
              > Reply-To: PPLetterpress@yahoogroups.com
              > Date: Wed, 9 Jan 2002 20:12:22 -0700
              > To: "'PPLetterpress@yahoogroups.com'" <PPLetterpress@yahoogroups.com>
              > Subject: RE: [PPLetterpress] Re: another possible factor in exposing plate s
              >
              > katie wrote, in part:
              >
              > 'If you render an 85-line halftone on a 300 dpi
              >> printer and compare it to an 85-line halftone rendered on a 1200 dpi
              >> printer, the 1200 dpi printer output will appear sharper, crisper and with
              >> better tonal rendition. If you look at both through a magnifier, you will
              >> see that the dots are the same size, but the 1200 dpi dot is finer and
              >> crisper.'
              >>
              > i get this, basically. but if polymer plates have a 'limit' of about
              > 150 lpi or 300 dpi, what use is the 1200 dpi file ? the file, or the
              > laserprint, may have more detail, but will that detail show up on a polymer
              > plate? this question may be more meaniful if, for example, one is committing
              > the heresy that i do, which is to generate negatives on my 600 dpi laser
              > printer.
              >
              > brian
              >
              >
              > To post a message to the membership, send an email to
              > PPLetterpress@yahoogroups.com
              >
              > To log on to the groupsite (confirmed Yahoo ID required), go to
              > http://groups.yahoogroups.com/group/PPLetterpress
              > [copious reference sources can be found onsite in Bookmarks (URLs),
              > Database (tables), Files (documents), and Messages (archives)]
              >
              > Encountering problems? send an email to
              > PPLetterpress-owner@yahoogroups.com
              >
              > To unsubscribe, send an email to
              > PPLetterpress-unsubscribe@yahoogroups.com
              >
              >
              >
              > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              >
              >
            • Brian Molanphy
              katie, i get this from info sheet from our plate supplier, gene becker: our plates... will hold a 3% dot on a 150 line screen. brian
              Message 6 of 7 , Jan 9, 2002
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                katie,

                i get this from info sheet from our plate supplier, gene becker: 'our
                plates... will hold a 3% dot on a 150 line screen.'

                brian

                > ----------
                > From: Katie Harper
                > Reply To: PPLetterpress@yahoogroups.com
                > Sent: Wednesday, January 9, 2002 8:40 PM
                > To: PPLetterpress@yahoogroups.com
                > Subject: Re: [PPLetterpress] Re: another possible factor in exposing
                > plate s
                >
                > Brian: I guess I don't quite get what you are saying about the "limit of
                > about 150 lpi or 300 dpi"... is this something you have read somewhere,
                > some
                > kind of specification? I'm sure that photopolymer probably does have a
                > limit
                > as to how small a speck it can hold (ie, how fine a halftone dot), but I'm
                > pretty sure it is capable of holding much finer detail than most
                > letterpresses can print, so the limitation you speak of is not from the
                > plate but from the press. In any case, I cannot see how a polymer plate
                > can
                > be limited by 300 dpi, since the plate is analog and the term "dpi" refers
                > to the digital world.
                >
                > And yes, the difference between output from a 600 dpi output device and a
                > 1200 dpi or larger resolution output device will show, but whether or not
                > that difference matters depends on a)what you are printing, b)what you are
                > printing on, c) what press you are using and d) what ink. There are
                > probably
                > other factors including temperature, roller condition, what the printer
                > has
                > for breakfast, and on and on... But it mainly depends on what is
                > acceptable
                > quality for the printer or the client. What works for a daily newspaper
                > won't be considered acceptable for a slick magazine or a coffee table book
                > printed in Italy. One plate may look like royal doo-doo on one type of
                > paper
                > and swell on another. For my own work, I tend to try to get the best
                > possible image from a plate, so that all the other factors which will
                > whittle down the quality have to start from a higher place. Having said
                > that, I will add there are times when a home-made neg will work and times
                > when it won't. Just as there are times when taking an exposed piece of
                > film
                > and scratching a drawing on it will make a great negative, and times when
                > I
                > need a careful rendering of an original or a computer file. I'm talking
                > images here. With type, I take no chances and get the best quality output
                > and plates I can.
                >
                > Katie Harper
                > Ars Brevis Press
                > Cincinnati, OH
                > 513-233-9588
                >
                > Remember: Book arts will save the world!
                >
                >
                >
                > > From: Brian Molanphy <bmolanphy@...>
                > > Reply-To: PPLetterpress@yahoogroups.com
                > > Date: Wed, 9 Jan 2002 20:12:22 -0700
                > > To: "'PPLetterpress@yahoogroups.com'" <PPLetterpress@yahoogroups.com>
                > > Subject: RE: [PPLetterpress] Re: another possible factor in exposing
                > plate s
                > >
                > > katie wrote, in part:
                > >
                > > 'If you render an 85-line halftone on a 300 dpi
                > >> printer and compare it to an 85-line halftone rendered on a 1200 dpi
                > >> printer, the 1200 dpi printer output will appear sharper, crisper and
                > with
                > >> better tonal rendition. If you look at both through a magnifier, you
                > will
                > >> see that the dots are the same size, but the 1200 dpi dot is finer and
                > >> crisper.'
                > >>
                > > i get this, basically. but if polymer plates have a 'limit' of about
                > > 150 lpi or 300 dpi, what use is the 1200 dpi file ? the file, or the
                > > laserprint, may have more detail, but will that detail show up on a
                > polymer
                > > plate? this question may be more meaniful if, for example, one is
                > committing
                > > the heresy that i do, which is to generate negatives on my 600 dpi laser
                > > printer.
                > >
                > > brian
                > >
                > >
                > > To post a message to the membership, send an email to
                > > PPLetterpress@yahoogroups.com
                > >
                > > To log on to the groupsite (confirmed Yahoo ID required), go to
                > > http://groups.yahoogroups.com/group/PPLetterpress
                > > [copious reference sources can be found onsite in Bookmarks (URLs),
                > > Database (tables), Files (documents), and Messages (archives)]
                > >
                > > Encountering problems? send an email to
                > > PPLetterpress-owner@yahoogroups.com
                > >
                > > To unsubscribe, send an email to
                > > PPLetterpress-unsubscribe@yahoogroups.com
                > >
                > >
                > >
                > > Your use of Yahoo! Groups is subject to
                > http://docs.yahoo.com/info/terms/
                > >
                > >
                >
                >
                >
                > To post a message to the membership, send an email to
                > PPLetterpress@yahoogroups.com
                >
                > To log on to the groupsite (confirmed Yahoo ID required), go to
                > http://groups.yahoogroups.com/group/PPLetterpress
                > [copious reference sources can be found onsite in Bookmarks (URLs),
                > Database (tables), Files (documents), and Messages (archives)]
                >
                > Encountering problems? send an email to
                > PPLetterpress-owner@yahoogroups.com
                >
                > To unsubscribe, send an email to
                > PPLetterpress-unsubscribe@yahoogroups.com
                >
                >
                >
                > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                >
                >
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