Graphics Formats for Linux
Having looked at some of the common graphics formats, we finish up with a quick look at some available programs and libraries for converting images.
xv and ImageMagick
These two X programs display, convert, and manipulate images. xv can read and write JPEG, GIF, TIFF, PBM/PGM/PPM, and X formats, although it cannot display 24bit images as 24bit. In addition to format conversions, xv can perform simple image manipulations, e.g., rotate, flip, crop, magnify, and gamma correction. ImageMagick supports the formats xv does, plus TGA. It can send output directly to a postscript printer and has more image manipulation capabilities than xv: cut, copy, paste, resize, flip, flop, rotate, invert, emboss, and more, on the whole or on part of the image.
The canonical way to view and convert from PostScript (including EPS) is ghostscript. Ghostscript operates both from the command line options and interactively. Input is always a PostScript file and output may be any of several different file formats, printer languages, or screen types. By default, ghostscript sends its output to an X terminal, but it can also save images to file. Ghostview is a popular front end for ghostscript that improves the screen handling.
The PBMPLUS utilities are a set of 120 programs for image conversion and manipulation. PBMPLUS defines three intermediate formats: PBM, PGM, and PPM (see listing above). The basic philosophy is that if there are twenty formats, you need twenty squared, or 400, programs/subroutines to convert between them. The use of intermediate formats reduces that number to two times twenty, or forty. In addition to the conversion programs, there are a number of simple image processing programs: scaling, rotating, smoothing, convolution, gamma, cropping and more. NETPLUS is a newer version of PBMPLUS, but some versions suffer from serious bugs.
C Library support
Substantial support exists for C programmers working with graphics. Libraries for JPEG/JFIF, TIFF, and PNG are now available. In addition, code fragments for many of the other formats are readily available from Internet archive sites.
IJG JPEG/JFIF library
The easiest way to do JPEG programming is to use the Independent JPEG Group's (IJG) library. This library is based on the JFIF specification and includes two common programs found on many Unix systems for storage and retrieval of JFIF images: cjpeg and djpeg. The library is available as source and compiled code.
SGI TIFF library
Like the JPEG library, a full set of routines to implement TIFF is available. Written by Sam Leffler and SGI, this library is also available as source and compiled code. The library includes programs for converting, dithering, splitting, and displaying information on TIFF files.
With the recent announcement of support for the PNG format, Compuserve also announced a PNG toolbox. The toolbox uses the zlib library for the LZ77 code and is intended to speed the acceptance of the new format. Its use will be free of royalties. A beta version is available on Compuserve.
There are several archive sites on the Internet where programs and further information can be found:
anonymous ftp sites:ftp://sgi.com/graphics/tiff TIFF version 6.0 specification and the source for the SGI TIFF libraryftp://sunsite.unc.edu/pub/Linux/apps/graphics/convert PBMPLUSftp://sunsite.unc.edu/pub/Linux/X11/xapps/graphics ImageMagickftp://sunsite.unc.edu/pub/Linux/libs/graphics Compiled version of JPEG and TIFF libraries for Linuxftp://sunsite.unc.edu/pub/Linux/apps/graphics/viewers Compiled version of ghostscript for Linuxftp://ftp.wuarchive.edu/ Numerous code fragments for image formats are scattered throughout this large archivecompuserve.com GRAPHSUPPORT forum, library 20, LP071.zip, the beta version of the PNG toolboxwww.uwm.edu/~ggraef. List of links and other direct links to format information
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
- Google's SwiftShader Released
- SUSE LLC's SUSE Manager
- My +1 Sword of Productivity
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Managing Linux Using Puppet
- Non-Linux FOSS: Caffeine!
- Interview with Patrick Volkerding
- SuperTuxKart 0.9.2 Released
- Parsing an RSS News Feed with a Bash Script
- Doing for User Space What We Did for Kernel Space
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide