Currently, the default compressed image format for amateur radio digital SSTV images has been jpeg2000 (file extension of jp2).
Both jpeg2000 and a similar ATT developed djvu system are wavelet type compression programs. Both are MRC (Mixed Raster Content) based which means that the document to be compressed is separated into components that are handled as separate layers, such as graphics, photographs, text, along with various backgrounds. Adobe also seems to have much more compression if you want it in their pdf's now although the pdf files were vector files in the past. I am not sure if this is true for those that are highly compressed. I did some major compression of docs with pictures with the built in pdf creator in Open Office and the results were about what I expected. The wavelet types of compression may work better, but I don't know for sure unless I had a way to do it in windows. To make it even more confusing there is a newer type of jpeg2000/part 6, (file extension jpm), but I am not very sure what advantages there are. A year or so ago I was looking at the djvu approach but it just did not seem to be going anywhere. It costs money to buy programs from commercial sources but now I realize that it is also open source. Many of these programs are extremely expensive to do the compression, although the readers are a free download. The Plug-in for Irfanview to make at jp2 is $90. Needless to say, this is a non-starter for most of us. There is a way to convert images to djvu with the on-line converter at: http://any2djvu.djvuzone.org/ As of today, I found out that djvu has been selected for the OLPC (One Laptop Per Child) computer software along with the Linux OS. Djvu has commercial software, but also has a Libre version at: http://djvulibre.djvuzone.org/ Binary packages are available for a number of Linux distros, but I am not sure about MS Windows other than from the commercial owners who are now LizardTech but that means you have to pay for encoding under Windows. They released some of the implementation under the GNU GPL in October 2000. Does anyone have personal experience with these programs? Thanks and ... 73, Rick, KV9U kd4e wrote: > >What about DjVu? Their file compression tends to be >exceptionally efficient. > >I believe they have versions for Apple, Linux, & MS. > > > >
