Image re-sizing

Discussion in 'Digital Photography' started by Eos, Apr 1, 2005.

  1. Eos

    Eos Guest

    Sorry for what might be an obvious question to most but I would
    appreciate a little advice on re-sizing an image.
    I currently have an image which is appreox 3.4 mb which I have been
    asked to send via e-mail at 100k.
    Using photoshop I go to Image size and adjust the pixel dimension to
    340 x 252 and save the JPEG at highest quality (12) and 72 pixels/inch.
    However although the image is very good when I send the image it
    appears quite small. Saving the image at a lesser image quality for a
    smaller file increases the size dispalyed but the image is noticeably
    poorer when dispalyed.
    I am a little confused however in that I have an e-mail which has been
    sent to me which has various pictures attached.
    These are reasonable quality (on monitor),display a larger image when
    opened, yet are only 30-40k in size !
    I would appreciate therefore any (easy) advice as to the best method to
    produce a 100k image which is going to give the best quality but yet be
    dispalyed at a reasonable size when sent.
    ( I understand quality v size is probably a trade off ) but your help
    is appreciated as to date I havn't really had to bother in reducing
    files for this purpose.

    Rob.
     
    Eos, Apr 1, 2005
    #1
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  2. This does seem to be a perennial question but I have found
    Photoshop Elements "Save for web" and Microsoft's Resize to
    produce results that most find acceptable in an e-mail. There
    are many other program commands that people will mention.

    Jim.
     
    James Silverton, Apr 1, 2005
    #2
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  3. Eos

    C Wright Guest

    Why a 340 x 252 image size? On a monitor that displays 96ppi (most monitors
    today display more than 72ppi) your image will be only about 3.5 in. by 2.5
    in. at full size. You don't say what lower compression quality you have
    tried but a quality of 8 rather than 12 usually produces good results. I
    would create an image of somewhat larger dimensions and use a higher
    compression.
    Chuck
     
    C Wright, Apr 1, 2005
    #3
  4. Eos

    DM Guest

    Hi Rob,


    Resize as you are doing to 800x? (? will depend on original image ratio).
    DO NOT alter the pixel/inch setting from the original images value!
    Save as JPEG quality 7
    Hopefully this should give you roughly what you're after.

    The constraint is the 100K size demand. To get a 1024 image to fit you'd
    have to use level 5 compression on saving the JPEG which is a bit too much
    for my liking.

    What is the need for the 100K constraint? 175-180 would allow an image
    1280x? at level 7 compression that (on screen) is almost indistinguishable
    from original quality.

    Regards

    DM
     
    DM, Apr 1, 2005
    #4
  5. Eos

    Jürgen Eidt Guest

    With cPicture you can resize by file size.
    There is the pixel size (480x320 for example), the file size and the JPEG
    quality.
    You can choose two of them and the 3rd is calculated.
    For example you set 100KB and 480x320, you will probably end up with a very
    good quality.
    If you choose a larger picture size and still 100KB, you will end up with a
    lower quality of course.
    And if you strip the picture data before sending as EMail (picture meta data
    like EXIF can be 20-30KB), you can also gain quality.
     
    Jürgen Eidt, Apr 2, 2005
    #5
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