Pamdepth User Manual



Pamdepth User Manual

NAME
SYNOPSIS
DESCRIPTION
SEE ALSO
HISTORY

NAME

pamdepth - change the depth (color resolution) in a Netpbm image

SYNOPSIS

pamdepth newmaxval [netpbmfile]

DESCRIPTION

This program is part of Netpbm(1)

pamdepth reads a Netpbm image as input, changes its depth (color resolution), and writes out the resulting Netpbm image. I.e. the output has a different maxval from the input, but all the same colors (apart from rounding error).

Reducing the depth results in some loss of information.

Here is an example of the effect at the image format level: Assume you start with an image with maxval 100 and sample values of 50 and 100. You tell pamdepth to change it to depth 150. The output has maxval 200 and sample values 75 and 150.

This program works on multi-image streams.

Be careful of off-by-one errors when choosing the new maxval. For instance, if you want the color values to be five bits wide, use a maxval of 31, not 32.

One important use of pamdepth is to convert a new format 2-byte-per-sample PNM file to the older 1-byte-per-sample format. Before April 2000, essentially all raw (binary) format PNM files had a maxval less than 256 and one byte per sample, and many programs may rely on that. If you specify a newmaxval less than 256, the resulting file should be readable by any program that worked with PNM files before April 2000.

SEE ALSO

pnm(5) , pam(5) , pnmquant(1) , ppmdither(1)

ppmbrighten(1)

pamfunc(1)

HISTORY

pamdepth was new in Netpbm 10.32 (February 2006). It replaced pnmdepth, by Jef Poskanzer. pamdepth is backward compatible with pnmdepth and adds the ability to process arbitrary PAM images and the ability to process multi-image input streams. pnmdepth handled only PNM images and ignored all but the first in any stream.







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.