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    Re: Navigation instruments from Paris, Maskelyne
    From: Peter Fogg
    Date: 2004 Jul 21, 13:35 +1000

    Photoshop is the most well known (and possibly the most demanding to use well) image management
    software. Since computer screens only output at about 72 pixels per inch (they vary) there usually is no
    reason to send pics for viewing on a monitor at a resolution any higher than this. In Photoshop,
    choose 'image size' then save a copy of your pic at this resolution and at an 
    appropriate size for viewing.
    Then convert it to .jpg file format, but only after you have completed all other operations, as this step
    loses image quality each time, the effects are accumulative. If your camera 
    records in .jpg then convert to
    another lossless format as the first step, then reconvert as the last. I 
    wouldn't be surprised to learn that
    there is software freely available that could do all this. Photoshop is really 
    a professional application and is
    quite expensive, although there are different versions available.
    "how to diminish them and not to degrade them too much" Photoshop certainly has wonderful tools. One of
    the most useful is a histogram, called 'levels', which is like a statistical 
    map of the amount of dark and light
    tones. Almost every picture can be improved by playing with its 'levels'. But 
    this is hardly scratching the
    surface of what is possible with computer image manipulation. There is much information online. Its a big
    Quoting Jan Kalivoda :
    > Hello, Joel,
    > thank you for your remark. I am fully aware of your troubles, but working
    > only from internet cafes in Paris, I cannot help you and me now. I will be
    > able to redress and republish my pictures only in August from Prague.
    > Meanwhile, can you give me advice about software and modes that shall I use?
    > I tried higher compression ratios for these JPG's, but the quality suffered.
    > And as these pictures are not the best even uncompressed (it was a bit
    > difficult to take them in an unsuitable room, deep behind the glass), I
    > wonder, how to diminish them and not to degrade them too much.
    > Thanks, Jan Kalivoda
    > Joel Jacobs writes:
    > > Hello Jan,
    > >
    > > Thank you for the invitation. But, the file sizes of you pictures average
    > > about 2 Megs. For some of us they take too long to load even with
    > broadband.
    > >
    > > Simple photo editing software would allow you to get the file size down to
    > > 20 KB and still have good pictures.
    > >
    > > BTW, The first picture is still working on opening.
    > >
    > > I very interested in what you published, but haven't more time,
    > >
    > > Joel Jacobs
    > >
    > >
    > >
    > >
    > > ----- Original Message -----
    > > From: "Jan Kalivoda" 
    > > To: 
    > > Sent: Monday, July 19, 2004 5:39 PM
    > > Subject: Navigation instruments from Paris, Maskelyne
    > >
    > >
    > >> Hello,
    > >>
    > >> if anybody wants, login to "http://www.xdrive.com" under the login
    > >> "navigation@seznam.cz" (XDRIVE allows only valid e-mail addresses as
    > > logins,
    > >> as you probably know), password "celnav".
    > >>
    > >> You have 60 MB photos of some historical navigation instruments kept in
    > > the
    > >> Marine Museum in Paris (directory "Musee de la Marine") there. I tried to
    > >> create the logical sequence of them from the nocturnal and the Jacob
    > staff
    > >> to repeating lunar circles.
    > >>
    > >> Of course, I am not a professional photographer and I didn't have the
    > >> instruments available "au plain air".
    > >>
    > >> At the end of this week, I shall obtain some copies of Maskelyne's less
    > >> known works printed in the 18th century. It would be interesting to chat
    > >> about them a bit in the list.
    > >>
    > >>
    > >> Jan Kalivoda

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