Re: Satellite Photography

From: Marco Langbroek (marco.langbroek@wanadoo.nl)
Date: Thu May 21 2009 - 08:32:15 UTC

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    John A. Dormer 2 schreef:
    > Technically, PNG's compression is "lossless" like the GIF type. JPEG
    > compression is always lossy unless the tools are told to use 100% of the
    > original pixels. Typically I have seen most tools use 70% (that is,
    > reduce the image size on disk to 70% of the original, effectively).
    
    In Photoshop, the dialogue asks if and how much compression you want. Setting 12 
    ("highest quality") means no compression (100% original pixels).
    
    With a camera, it is a matter of settings. The highest quality jpg option of my 
    EOS 450D uses no compression (100% original pixels) and that is what you should 
    use. Of course, it is possible to shoot in RAW too but then the file sizes 
    become very large.
    
    For the astrometry, for which I currently use AstroRecord, the JPG's are 
    converted to 8 bit b/w bitmaps before loading them into the software.
    
    - Marco
    
    
    -----
    Dr Marco Langbroek  -  SatTrackCam Leiden, the Netherlands.
    e-mail: sattrackcam@wanadoo.nl
    
    Cospar 4353 (Leiden):   52.15412 N, 4.49081 E (WGS84), +0 m ASL
    Cospar 4354 (De Wilck): 52.11685 N, 4.56016 E (WGS84), -2 m ASL
    SatTrackCam: http://home.wanadoo.nl/marco.langbroek/satcam.html
    Station (b)log: http://sattrackcam.blogspot.com
    -----
    
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