Lossy vs. Lossless

As others have cited, I thought that the combination of this week’s PowerPoint and Keely’s explanation of lossy vs. lossless image types really helped put a perspective on this issue (and oh my goodness I’ve flagged “Digital Image File Types Explained” as a favorite – so helpful!).  Image file size/compression came up a lot last semester in my Info Architecture course.  In the course we had to design a website, thinking through the effects that people’s different technology, browsers, etc would have on viewing the information.  Initially I was completely for always saving a file format in the most high-res version possible – but (especially if you have a lot of pictures on your website) the load time will be incredibly slow.  There are statistics floating about (http://mashable.com/2012/03/14/slow-website-stats-infographic/) citing that 1 in 4 people abandon a website if it takes more than four seconds to load; and 50% of mobile users abandon a page if it doesn’t load in 10 seconds (with 3 out of 5 never returning).   Most people are willing to sacrifice a perfect resolution in favor of efficiency.  I did really like Keely’s caveat that the Uprising Archive always save a TIFF file of their images that remains “pure” (since JPEG’s degrade) and in case something happens to the manipulated image.

I think that one use (that would likely not be noticed) of lossy images could be the “snapshot/cover” of a resource.  Some people are visual learners, and having a snapshot of the resource cover when searching for items could be helpful for jogging their memory of something they are interested in (I know I’ve used this frequently at the public library when I’ve forgotten the name of a book).   In general I think that most of the time librarians can get by with uploading lossy images to the webpages as long as they have the lossless version somewhere in their files.  Keely mentioned that the Uprising Archive will soon be adding the phrase “please contact us for a non-compressed/high quality version of this image/video” (if they were going to use it in a documentary for example).   


2 responses to “Lossy vs. Lossless

  1. Thanks for this reply! I’m glad that the example in the lecture helped drive the issue home visually for you! One note of clarification – unlike analog materials (think of an audio tape, for example), digital materials do not degrade upon each use or view. The issue with lossy formats such as a .jpeg is that each subsequent save _in that format_ creates more lossiness/compression. In this way, it is different from analog media such as casette tapes that were notorious for losing fidelity upon each use.

    Thanks for this additional resource!

  2. Thanks for the clarification, Sarah! At my work we have numerous photos (originating on a digital camera) that we would like to store for the long-term (in order to populate various reports, etc), so this distinction is quite important. Thanks again

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