Resizing JPGs to <10k

Discussion in 'Photoshop' started by GrooveJedi, Aug 27, 2003.

  1. GrooveJedi

    GrooveJedi Guest

    Hi everybody. I was wondering if someone could help me with the
    following dilemma:

    I am trying to downsize JPGs using Photoshop without losing too much
    of the integrity of the file. These files need to be small because
    they are for the web. Say for example I "Save for Web" and my JPG is
    about 40k. Are there any other methods for reducing the file size
    other than lowering the quality of the image? I've already lowered
    the quality of the image as much as I can afford to and the file is
    still about 19.5kb. I need the file to be less than 10kb but don't
    want the image to get blurred further.

    GrooveJedi, Aug 27, 2003
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  2. GrooveJedi

    David Guest

    The only real things you can do would be to reduce either the image size, or
    colours in the palette - though I'd be interested to hear other suggestions.

    David, Aug 27, 2003
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  3. GrooveJedi

    Littleboy Guest

    Hi GrooveJedi

    Extreme JPEG
    The second method for saving JPEGs in Photoshop is the Save for Web command
    (File > Save for Web.). You may have thought that Save for Web was just a
    fancy version of the Save As command, but there's a bit more to it. For
    starters, Save for Web does a better job of compression, even at the same
    relative quality setting (Save for Web uses a scale of 0-100% whereas Save
    As uses 0-12). For example, Figure 5a was saved with the Save As command at
    a quality setting of 6 (equivalent to 50%) resulting in a file size of 26K.
    Figure 5b was saved with Save for Web at a setting of 50% producing a file
    size of only 14K. There is no perceptible difference between the two images.

    Save for Web also allows you to perform weighted optimizations by using an
    alpha channel to vary the compression amounts in an image. (It's not as
    difficult as it sounds.) First, make a rough selection using the Lasso (L)
    or Quick Mask (Q) around the areas of your image containing important
    detail. The selection should not be exact (see Figure 6a). Next, save the
    selection to an alpha channel by selecting Select > Save Selection. The Save
    Selection dialog appears (Figure 6b). Choose New in the Channel box and type
    a name for the channel in the Name box (I called it "JPEG Mask", but it can
    be anything). Click OK and the selection will be saved as an alpha channel.
    You can remove the active selection by pressing Ctrl-D.

    Now open Save for Web (File > Save for Web). Select the 2-Up view in the
    upper left to compare your original document in the left pane to the JPEG
    preview on the right. Under the Settings box in the upper right, select JPEG
    High and click the mask button next to the Quality box (see Figure 6c). The
    Modify Quality Setting dialog now appears (Figure 6d). In the Channel
    drop-down box, select the name of the channel mask you created previously.
    Under Quality, slide the white slider to 70 and the black slider to 40 and
    click OK. This means that the masked area will have a quality of 70% and the
    rest of the image will be 40%. Click Save to name your new image and save it
    to disk. The final image is seen in Figure 7.

    Although it's a neat trick, weighted optimization can be a lot of work for a
    little gain. In my tests with typical photos at 400 to 600 pixels in length,
    I was only able to save a few Kbytes. In some cases I managed to increase
    the file size over standard optimization. It seems to work best with higher
    quality settings and, of course, varies from image to image. Whether or not
    the extra effort is worth a few saved bytes is up to you.

    Ok I admit, I didn't make this up myself ;)

    Check out this link to more useful information on treating images like a


    Littleboy ;)
    Littleboy, Aug 27, 2003
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