PhotoDude.com

Mon. Oct 06, 2003

Compressing the Compressed

Compressing the Compressed – Suppose your workplace had a very space-conscious parking deck that frowned on cars above a certain size. To accommodate this you select a subcompact car, carefully measured with that parking space in mind. You’ve put some time and effort into solving the space problem, and solved it to your satisfaction.

Then one day you come out of work, and discover that one of the parking attendants decided you didn’t choose a small enough car. So he compressed it. Your crumple zones are now crumpled, and your car looks like hell. But it takes up less space.

Keep that concept in mind, and read about the concept of ”dial-up acceleration”: ”In the past year, dial-up acceleration moved from an extra-cost add-on to a bonus component of America Online’s and EarthLink’s latest software, as well as that of other companies. Both America Online and EarthLink tout it as a reason to choose them over competitors.”

Part of the gain comes from local caches of frequently accessed pages, which, scaled across millions of users, can make a difference on the most highly trafficked sites. But much of the speed gain comes from altering the content: ”The obvious trade-off in dial-up acceleration is picture quality. Accelerators compress pictures, sometimes dramatically—EarthLink’s version, provided by San Jose-based Propel Software Corp., condensed a photo file on The Post’s site by a factor of four.”

Oh, you need to see that. Allow me to illustrate with a couple of popup examples: Standard Compression Image – 40KB, and Same Image Recompressed by a factor of four- 10 KB.

Lovely, eh? Can you see how a photographer on the web might be concerned about this trend?

Back to the Post: ”As a result, images look anywhere from slightly off to terrible under acceleration, depending on what settings you enable. EarthLink’s Propel software offers six levels of compression and allows you to reload an image at full quality, while AOL’s is only on or off, with no ability to see a photo in its original condition.”

I honestly thought this beast had been mostly slain, or at least ”contained.” It used to go by the name of .ART, a proprietary AOL ”image format,” which was essentially the same thing we’re talking about here. I used to see it on my Dad’s computer, and when I’d see the embarrassingly crappy display rendered on his monitor, bearing little resemblance to my original work, I wondered if he and Mom just thought I was a bad photographer. Anyway, I’d disable that preference every time I got over there.

Now, it’s a ”feature,” and it’s spreading. A feature that punishes those who’ve already done the most to reduce download times: ”Because dial-up accelerators apply the same degree of compression to every picture online, those images that have already been prepared for quick downloads will look the worst afterward.”

”’If the image has already been optimized for Web display and there isn’t a lot to remove out, you’re more likely to notice what we do,’ said David Murray, Propel’s executive vice president.”

Um, sir, if the image is accessible on the web, it has been optimized for web display. The person who created it decided to leave it at that level of compression for a reason. And if its load time vexes you, well, that’s why Al Gore gave us a ”Back” button.

You know, columnists eat up 700 word chunks on the web, when a web visitor can surely get the gist of what they’re saying if we reduce that by a factor of four, and downloading only 175 words for a whole column is a big savings. Especially when you multiply it across all the columns out there. Imagine the trickle down savings just from trimming Bob Novak’s columns.

But that would be altering original copyrighted content, reducing its size purely for the sake of making it download faster. And that would be wrong. Surely, no one would stand for that. Surely people would catch on to the con, and realize that they’re not actually getting the same thing faster, they’re getting less.

It just seems faster. Uglier, too.