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Thread: JPG Compression - The Bandwidth Saver Article




  1. #1
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    Trying to reduse bandwidth consume is always important. But grafics is not the only thing to shrink.
    http://Leknor.com/code/gziped.php?ur....tweaktown.com
    http://Leknor.com/code/gziped.php
    Or for you guys having your own dedicated server:
    http://www.remotecommunications.com/apache/mod_gzip/

  2. #2
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    Instead of using JPEG for screenshots of programs, use PNG instead, PNG has far better compression for screenshots of programs.

  3. #3
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    To be exact, all JPEG images are already compressed. However, most JPEG encoders default to a quality level of 75, which is quite high. This gives us the leeway for extra compression documented in this article.

    There are other considerations with image compression. For line art, screenshots of GUIS and other images with large solid blocks of color, GIFs or PNGs will work
    better - especially if you scale down the
    size of the palette as far as possible. Turn off those gradients in your window title bars, kids.

    Finally, yes, bandwidth costs are important, but it doesn't do to forget that most of your audience is still on the wrong side of a modem.

    -- wrong

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    Even though it doesn't have sliding bar thingies :) the best program for most image viewing and image work is <a href="http://irfanview.tuwien.ac.at/iview361.exe">Irfanview</a>.

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    I thought this article was going to go in depth about compressions of JPEG, apparently not.

    JPEG from memory, slices image into chunks, defines a central pixel as certain color, and then base the surrounding pixel's color upon that central one, as in +1, -1 etc. This gives it much benefit over GIF in terms of complex images (not to mention 24 bit color), except if the image gets TOO complex, there is virtually no benefit from compression.

    GIFs however are limited to 256 colors, but they can be used as adaptive palette and the # of colors reduced. They encode in horizontal line fashion, thus a stripped pic of black and white horizontally will be compressed much smaller as opposed to a same sized black and white verticaly striped picture. I'm surprised you did not use GIF for screenshots, with proper adjustments it will always come out better than JPEG, plus there will not be noise around text etc and compression artifacts.

    Pretty much nobody uses PNG though, even though it was intended to replace GIF (becuase of royalty cost). It is 32 bit (8 bit alpha channel, once again rarely used in everyday browsers), and lossless compression. To most people Jpeg is probably good enough for screenshots, and for other uses, GIF still rules, so there is not much demand for PNG.

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    The article was obviously aimed at non-techies, but somebody from Tweaktown (presumably Cameron Wilmot) posted this article at slashdot, a site with an audience well-versed in technology, web development, etc. To tweaktown: it's fine if you feel the need to hash together worthless, redundant articles, but its quite despicable to post them where they are NOT wanted in an effort to boost hits to your site. <a href="http://slashdot.org/article.pl?sid=02/04/20/141235&mode=thread&tid=152">Just see</a> how people have reacted.

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    Quote Originally Posted by Unregistered
    I thought this article was going to go in depth about compressions of JPEG, apparently not.
    To quote myself, Iíve written this basic article for webmasters and site owners showing how they can significantly reduce the amount of bandwidth they use by compressing JPG images, one of the most common formats for web images.
    Cameron "Mr.Tweak" Wilmot
    Managing Director
    Tweak Town Pty Ltd

  8. #8
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    Quote Originally Posted by Unregistered
    The article was obviously aimed at non-techies, but somebody from Tweaktown (presumably Cameron Wilmot) posted this article at slashdot, a site with an audience well-versed in technology, web development, etc. To tweaktown: it's fine if you feel the need to hash together worthless, redundant articles, but its quite despicable to post them where they are NOT wanted in an effort to boost hits to your site. <a href="http://slashdot.org/article.pl?sid=02/04/20/141235&mode=thread&tid=152">Just see</a> how people have reacted.
    Fair enough point, I can see why you might think that. Although, the article was not written just to be slashdotted, it was something I thought of doing spontaneously after posting it in our news and remembering past Slashdot features where I also posted under my name. If it was redundant, Slashdot wouldn't have posted it, hence it must be useful to some, my intended audience, webmasters with basic experience in this area.
    Cameron "Mr.Tweak" Wilmot
    Managing Director
    Tweak Town Pty Ltd

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    Well I wouldn't expect the typical Slashdot viewer to gain much from the article.
    (To my dismay, much of the content there is over my head - of course that doesn't stop me from poking around over there in an attempt to learn something. :) )

    But there are many webmasters that could benefit from this article.
    I hope they find it, and learn from it.
    Lots of graphics programs allow varying degrees of compression. It's not difficult yet somehow remains unused in many cases where it would be beneficial.

    As a sub-note to those who are actually learning something from this article;
    The same principles apply to those huge pictures you've been sending in emails too:(
    The reason a diamond shines so brightly is because it has many facets which reflect light.

  10. #10
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    Quote Originally Posted by Mr. C
    But there are many webmasters that could benefit from this article.
    I hope they find it, and learn from it.
    You're kidding right? Tweaktown is a "tech" website. People who therefore read it are interested in that sorta thing. What kind of moronic tech website "person" doesn't know about JPEG.
    I have NEVER visited a techie website that doesn't use JPEG or PNG even for large images.
    This "guide" is pointless, slasdotting it even more so. The only thing to be gained from slashdotting this is to see all the negative comments about it, which are all completely justified.

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