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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?

  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
    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.

    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

    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

  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.

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

    - 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:

    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.

  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.

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