Re: Need help in eliminating "bleed-through"

Anna C. Martin (mailto:martin@MAIL.CEDARNET.ORG)
Thu, 15 Jan 1998 14:02:42 -0600 

Message-Id: <199801152004.NAA52286@dns.ccit.arizona.edu>
Date:         Thu, 15 Jan 1998 14:02:42 -0600
From: "Anna C. Martin" <mailto:martin@MAIL.CEDARNET.ORG>
Subject:      Re: Need help in eliminating "bleed-through"
To: mailto:IMAGELIB@LISTSERV.ARIZONA.EDU


I've had good luck with removing pencil marks, erasures, and reverse-side
print that shows through newsprint articles by carefully narrowing the
threshold from within photoshop.  This adjustment is effective when the
marks (writing) you wish to select is monochromatic and uniform in value;
the threshold can be adjusted to eliminate values darker AND lighter than
the selected marks. Since we can assume the writing on the reverse will be
lighter in value, you will probably want to set the threshold to remove
all values lighter than a sample lf the ink on the top side of the
document. If you need more info, e-mail me at
mailto:martin@cedarnet.org


Good luck


Anna Martin, Ed. D
Chair, Electronic Media Interest Group
900 S. Irby St. Suite 347
Florence, SC 29505


http://www.cedarnet.org/mar


http://www.cedarnet.org/emig


On Thu, 15 Jan 1998, Robert Hershoff wrote:


> January 15, 1998

>

> The combination of a dark backing paper (previously mentioned by

> Peter Nelson) and some judicious adjustment of the scanner controls

> for brightness and contrast should make it possible to minimize the

> show-through.

>

> Please let us know how this works out.

>

> Regards,

>

> Robert

>

> *****************************************************

> Robert Hershoff / The University of Arizona Library

> Main Library Room A304 / 1510 E. University Boulevard

> P.O. Box 210055 / Tucson, AZ 85721-0055

> voice (520) 626-7415 / fax (520) 621-9733

> e-mail: mailto:hershoff@bird.library.arizona.edu

> *****************************************************

>

> On Thu, 15 Jan 1998, Patricia Bruce wrote:

>

> > Try placing a dark piece of paper behind the scanned object.  Black is

> > recommended, but you may need to try other dark colors, depending upon the

> > color of the ink.

> > "Peter Nelson" <mailto:pnelson@MTHOLYOKE.EDU> Wrote:

> > |

> > | Please excuse cross-posting.

> > |

> > | We are using a flatbed scanner and Photoshop 4.0 to create

> > | JPEG images of

> > | handwritten manuscripts, and recently encountered a series

> > | of documents

> > | written in dark ink on very thin onionskin paper.

> > | Consequently there is a

> > | bad "bleed-through" problem, i.e. writing on the verso can

> > | plainly be

> > | seen.  This results in nearly illegible text.  Does anyone

> > | on this list

> > | know of any trick, such as a mask or filter, that can

> > | reduce or eliminate

> > | this problem?  I should add that the original mss. present

> > | the same

> > | problem, so any solution would in effect be improving on

> > | the visual

> > | quality of the originals.

> > |

> > | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

> > | +-+-+-+-+-+

> > | Peter Nelson

> > | mailto:pnelson@mtholyoke.edu

> > | Five College Archives Digital Access Project

> > | c/o Mount Holyoke College Archives

> > | http://clio.fivecolleges.edu

> > | South Hadley, MA 01075

> > | (413) 538-3020

> > |        Don't anthropomorphize computers.  They don't like

> > | it.

> > | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

> > | +-+-+-+-+-+

> > |

> >

>