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JPG Compression - The Bandwidth Saver Article

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  • JPG Compression - The Bandwidth Saver Article

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

    Comment


    • #3
      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

      Comment


      • #4
        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>.

        Comment


        • #5
          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.

          Comment


          • #6
            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.

            Comment


            • #7
              Originally posted by Unregistered
              I thought this article was going to go in depth about compressions of JPEG, apparently not.
              To quote myself, I’ve 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

              Comment


              • #8
                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

                Comment


                • #9
                  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.

                  Comment


                  • #10
                    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.

                    Comment


                    • #11
                      The only "error" is the fact that I used the simplfied three letter DOS extension format, JPG, instead of JPEG because it is more common. This does not make everything else in the article incorrect, as you suggest.
                      Cameron "Mr.Tweak" Wilmot
                      Managing Director
                      Tweak Town Pty Ltd

                      Comment


                      • #12
                        Originally posted by Mr.Tweak
                        The only "error" is the fact that I used the simplfied three letter DOS extension format, JPG, instead of JPEG because it is more common. This does not make everything else in the article incorrect, as you suggest.
                        Oh please, don't try to pass it off as a "oh, whoops, DOS calls it that". Do you also refer to text files as txt files because Windows says thats the file extension to? No, because that would be dumb, just like calling them JPG when they are not is also.

                        Simplified my ass.

                        I also no-where suggested the rest was wrong. Though your ratios are wrong.

                        The "wrongness" extends from the fact your write a begineer JPEG article & don't even call it that. Heck you don't explain what JPEG is. Oh wait, you don't even call it what it actually is so why would you.

                        Comment


                        • #13
                          Judging by your comments, you seem to be one of those people who won't even attempt to see things from a different prospective. So, I'm not going to continue any further after this post.

                          As for ratios being incorrect, I'm only reporting it as I see it, and in this case it is what PSP reported. And I'll say it again, the article was intended to be basic and not be an extensive report on JPG or JPEG.

                          Some people you'll just never be able to keep happy. :(
                          Cameron "Mr.Tweak" Wilmot
                          Managing Director
                          Tweak Town Pty Ltd

                          Comment


                          • #14
                            Originally posted by Mr.Tweak
                            As for ratios being incorrect, I'm only reporting it as I see it, and in this case it is what PSP reported. And I'll say it again, the article was intended to be basic and not be an extensive report on JPG or JPEG.

                            Some people you'll just never be able to keep happy. :(
                            Ok lets see shall we. Page 2. Image details;
                            "Original Compressed Image (2:1) – 61.3kb"
                            "Highly Compressed Image (25:1) – 16.7kb"

                            Here you claim you compressed the "Highly Compressed Image" over the original compressed image above at a 25:1 ratio. 25:1 = 4% of the original size.
                            4% of 61.3k = 2.452k

                            Wait a minute!! But the "Highly Compressed Image" is 16.7k. UH-OH! Looks like someone can't use a calculator here.

                            Your "Highly Compressed Image" is in fact closer to 4:1 than 25:1 (3.67:1 in fact if you round the decimals up a little).

                            This throws your "article" into a whole new light doesn't it. It says 2 things;
                            A. I don't what JPEG is.
                            B. I can't do basic division.

                            Paint Shop Pro is not reporting "Compression ratio", it is reporting Compression %. You selected 25 PERCENT, not 25:1. My values prove here prove me right.

                            Please before you consider posting stuff can you at least check it's right?

                            Comment


                            • #15
                              just a quick note;
                              .jpg and .jpeg are the same, not 2 different types of files - just different file extensions.
                              If any confusion was caused by this, blame Microsoft. It seems they took the "Experts" out of the file extension:?:
                              The reason a diamond shines so brightly is because it has many facets which reflect light.

                              Comment

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