Pamgauss User Manual
Pamgauss User Manual
NAMESYNOPSIS
EXAMPLES
DESCRIPTION
OPTIONS
SEE ALSO
HISTORY
NAME
pamgauss - create a two dimensional gaussian function as a PAM image
SYNOPSIS
pamgauss width height -sigma=number [-maxval=number] [-tupletype=string]
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.
EXAMPLES
pamgauss 3 3
-sigma=.5 -tupletype=GRAYSCALE | pamtopnm >gauss.pgm
pnmconvol -nooffset gauss.pgm myimage.ppm
>blurred.ppm
DESCRIPTION
This program is part of Netpbm(1)
pamgauss generates a one-plane PAM image whose samples are a gaussian function of their distance from the center of the image. I.e. the sample value is highest in the center and goes down, in a bell curve shape, as you move away from the center.
The values are scaled so that the volume under the surface of the two-dimensional Gaussian function is the maxval of the image.
You can use this image as a convolution kernel with pnmconvol to blur an image. (This technique is known as Gaussian blurring).
width and height are the dimensions of the image that pamgauss generates. Mathematically speaking, they are the domain of the two dimensional gaussian function.
The sum of all the samples is equal to the image’s maxval (within rounding error). This is true even if you clip the Gaussian function by making the image too small. If you want to be sure you get a whole Gaussian function, make sure that you choose a sigma and image dimensions so that if you made it any larger, the sample values at the edges would be zero.
The output image is PAM. To make it usable with pnmconvol, specify -tupletype=GRAYSCALE so pnmconvol can use it as if it were PGM. You must use the -nooffset option on pnmconvol because zero means zero in the PAM that pamgauss generates.
OPTIONS
-sigma=number
This is the sigma parameter of the Gaussian function (if it were a Gaussian probability function, this would be its standard deviation). The higher the number, the more spread out the function is. Normally, you want to make this number low enough that the function reaches zero value before the edge of your image.
number is in units of pixels.
This option is required. There is no default.
-maxval=number
This is the maxval for the output image. It defaults to 255.
-tupletype=string
This is the value of the "tuple_type" attribute of the created PAM image. It can be any string up to 255 characters. If you don’t specify this, pamgauss generates a PAM with unspecified tuple type.
SEE ALSO
pnmconvol(1) , pamtopnm(1) , pgmkernel(1) , pamseq(1) , pam(5)
HISTORY
pamgauss was new in Netpbm 10.23 (July 2004).
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.
