pgmenhance(1) General Commands Manual pgmenhance(1)NAME
pgmenhance - edge-enhance a portable graymap
SYNOPSIS
pgmenhance [-N] [pgmfile]
DESCRIPTION
Reads a portable graymap as input. Enhances the edges, and writes a portable graymap as output.
The edge enhancing technique is taken from Philip R. Thompson's "xim" program, which in turn took it from section 6 of "Digital Halftones
by Dot Diffusion", D. E. Knuth, ACM Transaction on Graphics Vol. 6, No. 4, October 1987, which in turn got it from two 1976 papers by J. F.
Jarvis et. al.
OPTIONS
The optional -N flag should be a digit from 1 to 9. 1 is the lowest level of enhancement, 9 is the highest, The default is 9.
SEE ALSO pgmedge(1), pgm(5), pbm(5)AUTHOR
Copyright (C) 1989 by Jef Poskanzer.
13 January 1989 pgmenhance(1)
Check Out this Related Man Page
pgmedge(1) General Commands Manual pgmedge(1)NAME
pgmedge - edge-detect a portable graymap
SYNOPSIS
pgmedge [pgmfile]
DESCRIPTION
Reads a portable graymap as input. Outlines the edges, and writes a portable graymap as output. Piping the result through pgmtopbm
-threshold and playing with the threshold value will give a bitmap of the edges.
The edge detection technique used is to take the Pythagorean sum of two Sobel gradient operators at 90 degrees to each other. For more
details see "Digital Image Processing" by Gonzalez and Wintz, chapter 7.
The maxval of the output is the same as the maxval of the input The effect is better with larger maxvals, so you may want to increase the
maxval of the input by running it through pnmdepth first.
SEE ALSO pgmenhance(1), pgmtopbm(1), pnmdepth(1), pgm(5), pbm(5)AUTHOR
Copyright (C) 1991 by Jef Poskanzer.
04 February 1990 pgmedge(1)
Introduction
Originally, we only had one shell on unix. When ran a command, the shell would attempt to invoke one of the exec() system calls on it. It the command was an executable, the exec would succeed and the command would run. If the exec() failed, the shell would not give up, instead it... (3 Replies)
FreeBSD Kernel Internals, Dr. Marshall Kirk McKusick
nwbqBdghh6E
The first hour of Marshall Kirk McKusick's course on FreeBSD kernel internals based on his book, The Design and Implementation of the FreeBSD Operating System. (0 Replies)
Introduction
I have seen some misinformation regarding Unix file permissions. I will try to set the record straight. Take a look at this example of some output from ls:
$ ls -ld /usr/bin /usr/bin/cat
drwxrwxr-x 3 root bin 8704 Sep 23 2004 /usr/bin
-r-xr-xr-x 1 bin bin ... (6 Replies)
Suppose I have a main() function with only one malloc statement allocating say some 1 gb memory. Also say my system has 1 gb of ram.
main()
{
malloc(1gb)
return(0)
}
The program above exits without freeing the memory.
In this case will the 1 gb of heap memory be returned... (9 Replies)
I see lot of ad-hoc shell scripts in our servers which don't have a shebang at the beginning .
Does this mean that it will run on any shell ?
Is it a good practice to create scripts (even ad-hoc ones) without shebang ? (16 Replies)
Hi everyone,
I know the following questions are noobish questions but I am asking them because I am confused about the basics of history behind UNIX and LINUX.
Ok onto business, my questions are-:
Was/Is UNIX ever an open source operating system ?
If UNIX was... (21 Replies)
A shout out to Scott who gave me a helping hand to turn a simple sample Vue.js app I wrote yesterday into a Vue.js component:
Vue.component("unix-time", {
template: `<div class="time">{{unixtime}}</div>`,
data() {
return {
unixtime: ""
};
},
methods: {
... (1 Reply)
i read here that linux provides no way to determine when a directory was created.
https://www.unix.com/shell-programming-and-scripting/157874-creation-date-directory.htmlI have a directory /home/andy/scripts that had a README file in it.
That file says
I put the script in that directory and... (3 Replies)
Hello.
I can use any particular (stupid or not) format when using bash date command.
Example :
~> date --date "now" '+%Y-%m-%d %H!%M!%S'
2019-06-03 12!55!33or
~> date --date "now" '+%Y£%m£%d %H¤%M¤%S'
2019£06£03 12¤57¤36
or
~> date --date "now" '+%Y-%m-%d %H-%M-%S'
2019-06-03 12-58-51
... (4 Replies)
Morning All
So, I am starting looking into the world of UNIX for a new job (luckily not my primary function!) and I am looking to get stared. Like anything I seem to learn best by trying things out first in an environment but I have a key question:
Currently I use Oracle VirtualBox, can... (8 Replies)
I've installed Slack 14.2 on /dev/sda1 (/dev/sda2 is swap) and FreeBSD 12 on /dev/sda3 and lilo is the boot manager.
FreeBSD slices are as follows;
/ on /dev/ada0S3a, swap on /dev/ada0s3e, /var on /dev/ada0s3b, /tmp on /dev/ada0s3d and /usr on /dev/ada0s3f.
I hesitate to install Solaris 10... (2 Replies)
I'm trying to use a bash script for a psych experiment that involves listening to sound files and responding. If I have something like the code below, how can I make sure that a key press is assigned to RESPONSE only after the second echo statement?
for i in 1 2 3; do
echo "Ready?"
sleep 2
... (10 Replies)