Chris comments: | Ooh, I like this one better. I imagine it's what you use in | tune-finder, am I right? It give a nice compact image (unlike convert, | which makes too much whitespace), and quite small files as well (reduced | by about a factor of 10).
Yup; I just copied my script verbatim. It doesn't produce much of a white border at all. You've probably found that the "resolution" arg controls the size of the image.
| These should get me started with my project quite nicely.
One thing you might start to worry about: There has been more discussion lately on some other lists about the fact that GIF is a proprietary, patented format, and the owner (apparently now Compuserve) has been making noises about collecting royalties. When this happens every year or so, it persuades more people to switch to PNG, which is very similar to GIF in most respects (and typically about 20% smaller), but is a public standard.
That is, unfortunately, not the correct story. Compuserve does not own the patent on GIF, and they really wish there wasn't one. Unisys owns the patent on GIF.
What happened: In 1983, three researchers at Sperry created a variant on an existing data compression technique that had been previously invented by one of them. They published this technique in a journal, and didn't mention in the article that Sperry was seeking a patent on the technique. The algorithm got known by the initials of the thre inventors: LZW
The technique was superior to the majority of data compression algorithms that came before it -- it was a streaming compressor, it adapted to the exact data stream it was compressing, it used a small amount of memory, it was simple to describe and implement, etc. It was so good, and so much better, that almost immediately someone wrote tools for Unix (compress and uncompress) that used the technique, the ARC set of DOS utilities were was based around it, and the folks at Compuserve thought they had a solution to a problem they were facing.
Compuserve was the premier dialup network service of the day, and file exchange was a very popular feature of Compuserve. And people were exchanging graphics files like crazy. The problem was: graphics files are huge, and there are lots of different formats. So lots of time was spent uploading and downloading huge graphics files that weren't certain to work in the end anyway. And sometimes the file areas would be filled with multiple copies of the same, huge, image in different formats.
Compuserve wanted an open, easy to use, graphics interchange format that programmers could write conversion tools to and from, that was compressed in some way, so there would only have to be one, small, copy of each image on their system (as well as the tools to work with it), and thus make it easier on their customers.
LZW fit the bill they needed for compression. In 1987, they developed and published an open, well-documented file format called GIF87a that utilized a header that identified the properties of the image (like height, width, and colors used), and a body that consisted of raw image data that had been LZW compressed.
GIF87a solved their problem almost immediately. Very quickly, GIF became the default choice for graphics interchange, because it was so much better than every other choice. The format was tweaked once in 1989, giving the GIF89a format, but other than that, it's been fixed.
Compuserve made it an open, non-proprietary format because they wanted people to use it. Compuserve wasn't in the graphics business; they were in the communications business, and letting everyone and anyone write and develop GIF tools fostered communication.
By the mid-1990's, the compression world had changed. LZW opened up a wide vista of compression research and other compressors had taken over most uses of LZW. Some of this was pushed by lawsuits (PKWare was sued by ARC over its PKArc product, forcing Phil Katz to develop the ZIP file format, which deliberately uses a public domain incompatable compressor that is better than LZW), and some of it is simple adoption of newer, more appropriate technologies.
However, in the mid 1990's, years after GIF became firmly entrenched everywhere, including the nascent world-wide-web, Unisys (which had bought out Sperry) looked through their patent portfolio and found the LZW patent, which Honeywell had only applied to hardware implementations of the compressor. Unisys decided that it may apply to software implementations as well, and saw that Compuserve's GIF format was the major user of it in software. Unisys contacted Compuserve (who didn't know about the patent), and Compuserve sent out a general notice that a patent covered GIF files, this was a developing issue, royalties may be involved, etc.
So everyone blames the messenger, Compuserve, for patenting GIF, when they didn't have anything to do with it, and wouldn't be collecting royalties anyway.
Reading GIF files and displaying them is legal, but if you generate them without a license, you are violating the patent. So far the patent owners have always backed off on this threat, but who knows what they'll do next month? This isn't a really big deal, though. Most software that uses GIF will also accept PNG, and it's easy to convert (or use both) when the need arises.
It really isn't a big deal... the US patent either expired last December or it will expire this June. The European patents appear to be valid unitl June 2004. Give it a little more than a year, and the whole patent issue will be gone.
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