Fwd: [magick-users] Convert photos for laser engraving?

[Ross Presser]

I just realized I forgot to send this to the whole list instead of just George.

---------- Forwarded message ----------
From: Ross Presser <rpresser at gmail.com>
Date: Wed, 7 Nov 2007 15:52:08 -0500
Subject: Re: [magick-users] Convert photos for laser engraving?
To: George Vandenberghe <George.Vandenberghe at noaa.gov>

I've worked with converting grayscale images into 1bpp versions for
two different classes of device: inkjet printing, which prefers a
dithered image, and offset press plate printing, which prefers a
halftoned image.  Imagemagick is very good at producing dithered
images, not so good at halftoning. For halftoning I was forced to
bring in Ghostscript.

The third way to go to 1bpp is quantization or thresholding, where you
just take anything brighter than a certain point and make it white and
anything darker is black.

The slides from this lecture give a very good introduction to the differences:
http://www.cs.princeton.edu/courses/archive/fall99/cs426/lectures/dither/sld001.htm

During 2001, at Walt Disney World in Florida, visitors were invited to
have their photograph taken and a laser engraving on metal was placed
at a "leave a legacy" monument. The method used to laser engrave seems
to be dithering. Hard to be positive from these images.
http://www.wdwmagic.com/2000_legacy.htm
http://www.webmikey.com/images/trips/epcot2007.jpg
http://www.wdwplanner.com/Images/Leave%20a%20Legacy/lal.jpg

Edge detection is something yet again. It would be suitable if you
needed to produce a charcoal-sketch-like version of a photograph.


On 11/7/07, George Vandenberghe <George.Vandenberghe at noaa.gov> wrote:
> As someone who doesn't do much with images anymore you should take my
> advice cautiously.   However the PBM file format is a simple way
> to represent black/white images one bit per pixel.   The only way
> to get grayscale with PBM is by varying the density of black and white
> points.
> Look at the dithering options in convert for possible assistance.    However
> dithering does point density manipulation and lines are  a problem I've not
> worked with.
>
>
> Kent wrote:
> > Hi folks --
> >
> > I have a client who wants software to convert photo images into a form
> > that can be laser-engraved into metal or wood.  I suppose this will
> > involve edge detection, and/or a way to translate the gray scale into
> > patterns of lines that give the impression of varying shades.  The
> > client has specified that the resulting files must be 1 bit per
> > pixel.  Can IM & MagickWand do this?  Does anyone have recommendations
> > on what sort of operations to use?
> >
> > Thanks --
> >
> >   Kent Multer                  |\  /|
> >   Magic Metal Productions      | \/ |
> >   http://TheMagicM.com         |    |
> >
> >  * Web developer/designer
> >  * Author, The Official Miva Web Scripting Book -- available on-line:
> >    http://www.amazon.com/exec/obidos/ISBN=0966103211/magicmetalproducA
> >
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>
>
> --
> George VandenBerghe
> IMSG  Corp.
> 301-763-8115x7119
> George.VandenBerghe at noaa.gov
> DO NOT RESPOND TO lnx4 address!!
>
>
>
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