Jpeg2ktopam User Manual



Jpeg2ktopam User Manual

NAME
SYNOPSIS
OPTION USAGE
DESCRIPTION
OPTIONS
EXAMPLES
ABOUT JPEG-2000
SEE ALSO
History

NAME

jpeg2ktopam - convert JPEG-2000 code stream to PAM/PNM

SYNOPSIS

jpeg2ktopam [-verbose] [-debuglevel=number] filename

OPTION USAGE

Minimum unique abbreviation of option is acceptable. You may use double hyphens instead of single hyphen to denote options. You may use white space in place of the equals sign to separate an option name from its value.

DESCRIPTION

This program is part of Netpbm(1)

jpeg2ktopam converts the named JPEG-2000 file (JP2 or JPC), or Standard Input if no file is named, to a PBM, PGM, PPM, or PAM file on Standard Output.

The JPEG-2000 specification specifies two different formats: JP2 and JPEG-2000 code stream (JPC). JP2 represents a visual image quite specifically, whereas JPC is a more or less arbitrary array of codes. A JP2 image contains a JPC stream and metadata describing how that stream represents a visual image. jpeg2ktopam converts both.

If the color space identified in the image is grayscale (JAS_IMAGE_CS_GRAY), jpeg2ktopam generates a PGM image, unless the image contains only one bit per pixel, in which case jpeg2ktopam generates PBM. If the color space is RGB (JAS_IMAGE_CS_RGB), jpeg2ktopam generates a PPM image. If the input image is anything else, jpeg2ktopam generates a PAM image with no tuple type identified.

In the PGM and PPM cases, jpeg2ktopam assumes the intensity values in the input image have the same meaning as for PGM and PPM. One thing that implies is the ITU-R Recommendation BT.709 color space, which means the assumption is false for JP2 input. JP2 input uses SRGB color encoding. So if you use jpeg2ktopam to convert a JP2 image to PPM, it changes the visual image (slightly) -- the colors in the output are not the same as in the input.

In the PAM image, the output samples are numerically identical to the input samples. If the input samples are signed, they are represented in two’s complement form in the output (because PAM samples are always unsigned). The PAM plane numbers are identical to the JPC component numbers.

A JPEG-2000 image has a "precision," which is the number of bits used for each code (in Netpbm lingo, "sample"). Actually, each component has a separate precision. The maxval of a PGM, PPM, or PAM output is the largest number you can represent in the JPEG-2000 precision of the JPEG-2000 component with the greatest precision. The samples in all components are scaled to that maxval. So if the red component has a precision of 4 bits and the green component has a precision of 6 bits, the maxval is 63 and the red component codes from the JPEG-2000 image are multiplied by 63/15 to generate the output samples.

jpeg2ktopam interprets the JPEG-2000 input with the ("http://www.ece.uvic.ca/~mdadams/jasper/") Jasper JPEG-2000 library . See documentation of the library for details on what jpeg2ktopam handles. Note that the Jasper library contains facilities for writing PNM images, but jpeg2ktopam does not use those. It uses the Netpbm library instead. Note that the makers of the Jasper library write it "JasPer," but Netpbm documentation follows standard American English typography rules, which don’t allow that kind of capitalization.

Use pamtojpeg2k to convert in the other direction.

The program jasper, which is packaged with the Jasper JPEG-2000 library, also converts between JPEG-2000 and PNM formats. Because it’s packaged with the library, it may exploit it better, especially recently added features. However, since it does not use the Netpbm library to read and write the Netpbm formats, it doesn’t do as good a job on that side.

OPTIONS

-verbose

This option causes jpeg2ktopam to issue informational messages about the conversion process.

-debuglevel=number

This option controls debug messages from the Jasper library. jpeg2ktopam passes number as the debug level to the Jasper JPEG-2000 decoder.

EXAMPLES

jpeg2ktopam myimg.jpc >myimg.ppm

ABOUT JPEG-2000

See thepamtojpeg2kmanual(1)

for general information on JPEG-2000 compression and the JPEG-2000 formats.

SEE ALSO

pamtojpeg2k(1) , pnmtopeg(1) , ppm(5) , pgm(5) , pbm(5) , pam(5) ,

History

jpeg2ktopam was added to Netpbm in Release 10.12 (November 2002).

Before Netpbm 10.49 (December 2009), jpeg2ktopam could not convert a JP2 file -- only JPC.







Opportunity


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


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.





Free Books


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.





Education


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.