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jpeg compression

Discussion in 'Electronic Design' started by Joe G \(Home\), Aug 3, 2005.

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  1. Hi All,

    I want to take a simple JPEG file on a PC and compress it say in to 320x240
    B&W file.

    What steps do I need to take?

    Where can I get the JPEG std file format?

    What challengers do you think I need to meet?


    Regards
    Joseph
     
  2. Ban

    Ban Guest

    You can do that with paint, with the shrink/stretch function, but you have
    to calculate the percentage. Also the B/W conversion is faulty in paint.
    I use the free screen capture program 20/20
    http://www.sofotex.com/20/20-download_L230.html
    for this kind of stuff. It also converts .bmp to .gif, extremly useful for
    circuit diagrams.
     
  3. JeffM

    JeffM Guest

    I want to take a simple JPEG file on a PC and compress it
    The Swiss Army Knife of graphics programs for Windoze
    is a freeware app called IrfanView. http://www.irfanview.com

    Image; Convert to greyscale
    Image; Resize
    File; Save as
     
  4. René

    René Guest

    Same here, I have Photoshop, but use Irfanview 95% of the time for
    light conversion work (also batch conversion!)
     
  5. qrk

    qrk Guest

    http://perso.wanadoo.fr/pierre.g/xnview/endownload.html

    Or, you can use a subset of XNVIEW which is NCONVERT on the same site.
    Nconvert is a command line converter, perfect for batch jobs/scripts
    and calling from other programs. Cost: free. Works on most common
    operating systems.

    Since nconvert is hard to figure out, here is a starter for you:
    nconvert -grey 256 -resize 320 240 -out jpeg -o OutName.jpg InName.jpg

    You many want to set the compression level (-q) as the default is best
    quality.

    ===
    Mark
     
  6. YD

    YD Guest

    The GIMP. Really good but hell on wheels to get to grips with at
    first. It's cheap too, like in freeware.

    http://www.gimp.org/windows/

    While you're there have a gander at the docs and tuts, you'll need
    them.

    - YD.
     
  7. Buddy Smith

    Buddy Smith Guest

    If you want to do it yourself out of curiosity, I'd start by looking at
    jpeg-6b from IJG.

    You can get it here:
    ftp://ftp.uu.net/graphics/jpeg/

    It compiles in windows and unix/linux/etc.
    If you want to implement it yourself, it's quite complex. I'd start with
    reading the docs and looking around jpeg-6b. btw, most JPEGs you get
    are in "JFIF" format.

    --buddy
     
  8. Norm Dresner

    Norm Dresner Guest

    If you have a not-too recent copy of Microsoft Office (up to Office XP but
    not 2003), there's a program called Microsoft Photo Editor that comes with
    it that does a dandy job of resizing image (including JPG) files, among
    other things.

    Norm
     
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