fpack - FITS image compression program
funpack [OPTION]... FILE...
fpack is a utility program for optimally compressing images in the FITS data format. This programs is analogous to the GZIP utility program except that it is optimized for FITS format images and offer a wider choice of compression options.
Flags must be separate and appear before filenames. Use '-' to read from stdin. The compression parameters specified on the fpack command line may be overridden by compression directive keywords in the header of each HDU of the input file(s). -r Rice compression (default). -h Hcompress compression. -g or -g1 GZIP_1 (per-tile) compression. -g2 GZIP_2 (per-tile) compression (with byte shuffling). -p PLIO compression (only for positive 8 or 16-bit integer images). -d Tile the image without compression (debugging mode). -w Compress the whole image as a single large tile. -t axes Comma separated list of tile dimensions (default is row by row). -q level Quantized level spacing when converting floating point images to scaled integers. (+value relative to sigma of background noise; -value is absolute). Default q value of 4 gives a compression ratio of about 6 with very high fidelity (only 0.26% increase in noise). Using q values of 2, or 1 will give compression ratios of about 8, or 10, respectively (with 1.0% or 4.1% noise increase). The scaled quantized values are randomly dithered using a seed value determined from the system clock at run time. Use -q0 instead of -q to suppress random dithering. Use -qz instead of -q to not dither zero-valued pixels. Use -qt or -qzt to compute random dithering seed from first tile checksum. Use -qN or -qzN, (N in range 1 to 10000) to use a specific dithering seed. Floating-point images can be losslessly compressed by selecting the GZIP algorithm and specifying -q 0, but this is slower and often produces much less compression than the default quantization method. -i2f Convert integer images to floating point, then quantize and compress using the specified q level. When used appropriately, this lossy compression method can give much better compression than the normal lossless compression methods without significant loss of information. The -n3ratio and -n3min flags control the minimum noise thresholds; Images below these thresholds will be losslessly compressed. -n3ratio Minimum ratio of background noise sigma divided by q. Default = 2.0. -n3min Minimum background noise sigma. Default = 6. The -i2f flag will be ignored if the noise level in the image does not exceed both thresholds. -s scale Scale factor for lossy Hcompress (default = 0 = lossless) (+values relative to RMS noise; -value is absolute) -n noise Rescale scaled-integer images to reduce noise and improve compression. -v Verbose mode; list each file as it is processed. -T Show compression algorithm comparison test statistics; files unchanged. -R file Write the comparison test report (above) to a text file. -table Compress FITS binary tables using prototype method, as well as compress any image HDUs. This option is intended for experimental use. -tableonly Compress only FITS binary tables using prototype method; do not compress any image HDUs. This option is intended for experimental use. -F Overwrite input file by output file with same name. -D Delete input file after writing output. -Y Suppress prompts to confirm -F or -D options. -S Output compressed FITS files to STDOUT. -L List contents; files unchanged. -C Don't update FITS checksum keywords. -H Show this message. -V Show version number.
funpack(1), fitscopy(1).
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.