On Tuesday 25 April 2006 11:00, Frank Schoep wrote: > ... > To summarize: before we make any decisions on my initial analysis I'd like > to investigate the correctness of the numbers I provided, I hope this won't > pose a problem. The timespan for this is about two or three days. > ...
Today I've finished my new analysis and I'm presenting the results here, first of all the summarized conclusions, then a bit more background information and at the bottom of this email are the raw numbers to base my report on. Brief Summary ============================= By removing duplicate images and recompressing all image files we can save about 21 megabytes in the uncompressed default Dapper installation and shave off anywhere from 11 to 21 megabytes from the installation CD. This last figure depends on the unpredictable actual compression ratio of the package file format. Detailed Summary ============================= There are 12114 filenames matching the PNG extension, of which 9420 are actual files, 2694 are symbolic links. I ignored symbolic links in the calculations because they do not take up "space" themselves and can not be optimized further for distribution. In the current situation, all 9420 image files take up a total of 50 Mb uncompressed and 39 Mb compressed (bzip2). To save space I first checked for duplicate images, there were 1888 (!) binary duplicate images in the default installation which could easily be replaced by symlinks saving about 8 Mb. Next up I tried recompressing the remaining unique images, this shrunk the uncompressed size from 42 Mb to 29 Mb, the compressed size shrunk from 35 Mb to 29 Mb. I actually experimented with different OptiPNG settings because the initial recompression time was over 10 hours: using the default optimization level, recompression time dropped to half an hour for all 7531 unique images and the compression ratio was almost the same (neglible difference). Raw Statistics ============================= Dapper Beta with updates on April 25th, 2006 12114 filenames matching *.png in /usr 9420 actual files 2694 symbolic links 9420 actual files, 50.745.810 bytes 7531 unique files, 42.740.715 bytes 1888 duplicates, 8.005.095 bytes Original files including dupes, 50.745.810 bytes Original unique files, 42.740.715 bytes Recompressed (fast) unique files, 29.567.194 bytes Recompressed (max) unique files, 29.357.713 bytes Original files including dupes tar-bzip2'ed, 39.161.467 bytes Original unique files tar-bzip2'ed, 34.905.515 bytes Recompressed (fast) unique files tar-bzip2'ed, 28.892.262 bytes Recompressed (max) unique files tar-bzip2'ed, 28.911.620 bytes Time taken for recompression (fast): about 30 minutes Time taken for recompression (max): about 10 hours Final Words ============================= I hope this more thorough provides a starting point for a discussion on the idea of recompressing PNGs in Ubuntu. I'd be happy to provide more information on the methods and tools I used to generate the results and I'd gladly help out adapt package build processes to automatically optimize PNGs. If it is useful I would be able to provide a list of all duplicate images found in the current Dapper installation so that these can be replaced by symlinks. With kind regards, Frank Schoep (Apologies for cross-posting, but I'm not sure on which list to send this to, if you have strong objections to this, please notify me!) -- ubuntu-art mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-art
