How to compile OpenCV to utilize multiple core processor in Linux

Hello there, today I am gonna tell you the story that how I was able to utilize my Core i7 (eight cores) successfully during Haartraining of samples. Usually, OpenCV can utilize only one processor core at a time which cause huge time(3-4 days, even more) to get the training results. The secret is that we are going to use OpenMP(Open Multi-Processing) instead of TBB(Threading Building Blocks) during OpenCV Compilation.

Prerequisite:

GCC and build-essentials are required to build the source.

Steps:

Step 1: Download OpenCV source from here and extract.
Step 2: Install CMake & CMake UI
For ubuntu and mint:

sudo apt-get install cmake cmake-qt-gui

For RedHat and Fedora:

sudo yum install cmake cmake-qt-gui

Step 3: Open Terminal and change Directory (cd) to OpenCV source path, create a new folder in which you want to save the configured source of OpenCV which we are going to build, for example, we have OpenCV 2.4.6.1 here extracted into ~/opencv-2.4.6.1/ and we are going to create a directory ~/opencv-2.4.6.1/build/ for the configured source

Step 4: Edit and replace the lines 49 to 58 in file ~/opencv-2.4.6.1/cmake/OpenCVFindLibsPerf.cmake, for other versions of OpenCV, open that file and search for the OpenMP part and replace the part with the following lines.

# — OpenMP —
if(NOT HAVE_TBB AND NOT HAVE_CSTRIPES)
include (FindOpenMP) # — since cmake version 2.6.3
if (OPENMP_FOUND)
set (HAVE_OPENMP TRUE)
set (CMAKE_CXX_FLAGS “${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}”)
set (CMAKE_C_FLAGS “${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}”)
else()
set ( HAVE_OPENMP FALSE)
endif()
else()
set(HAVE_OPENMP 0)
endif()

Step 5: Run CMake GUI, and Source and Build paths to ~/opencv-2.4.6.1/ and ~/opencv-2.4.6.1/build/ respectively, press Configure and check whether OpenMP is enabled or not. If OpenMP is enabled, press Generate to save the configured source to ~/opencv-2.4.6.1/build/ directory, else recheck which step you have missed.

Step 6: Now, we are going to build the configured source, cd to ~/opencv-2.4.6.1/build/, run make to build and sudo make install to install OpenCV Binaries to the system

In order to test that you can collect your own negative and positive data set, create samples and follow the tutorial here. For me, it works like wow 🙂

Thanks, bye 🙂

How to capture terminal sessions (remote/local) in Linux

Hello everyone 🙂

If you want to put an eagle eye on your system, specially on industrial production systems running on any distributions of Linux, you have modify the shell for those users who are going to access the system. Suppose the name of our shell is cocoon, just a name and we are going to create a user anonymous who’s activity we need to capture. Root privilege is required for that.

First create the required shell

touch /bin/cocoon

Make it accessible

chmod 755 /bin/cocoon

Edit the file /bin/cocoon and write the following lines & save to complete the script.

#!/bin/sh
USER=$(whoami)
LOG_FOLDER=/var/log/ssh/${USER}
DATE=$(date +’%Y-%m-%d_%H:%M:%S’)
HOST=`hostname`
LOG_FILE=${LOG_FOLDER}/${HOST}_${DATE}.log
[ ! -d ${LOG_FOLDER} ] && mkdir -p ${LOG_FOLDER}
bash -i 2>&1 | tee ${LOG_FILE}

Now the shell is ready, we are going to create the user and assign this shell to it.

Create user anonymous and set cocoon as its shell 

useradd anonymous -s /bin/cocoon -m

Set a password for user anonymous

passwd anonymous

Finally change the permission of the log directory which we have mentioned in the shell

chmod 755 /var/log/ssh

That’s all. Now you can find the log of the sessions of user anonymous in /var/log/ssh/anonymous. 

How to run vlc player as root without compiling again

Vlc player exits with an error if you try to run it from terminal as root. However, there is a trick to run vlc player as root (without recompiling). The credit of the post goes to Net_Spy (http://www.linuxquestions.org/). The steps are as follows.

Step-1: Open a hex editor preferably ghex/khex. If u didn’t have one then download ghex editor from here and install (after resolving dependencies).
Step-2: Now open vlc binary (by default /usr/bin/vlc) into the hex editor, make a backup before that.
Step-3: Now search for the following string

geteuid

Step-4: Edit the string as follows

getppid

Step-4: click on Save

That’s all. Thanks 🙂

Job Scheduling in LINUX

Cron is a time based job scheduler for Unix based OS.  Most of the Linux Distributions have it installed. Job scheduling is much more simple with cron. First of all, make sure that cron is installed.

rpm -qa crontabs

If output shows something then cron is installed. Otherwise we can install it.

yum install crontabs

Suppose we have to run a copy operation (for backup purpose) everyday at 12:01pm. The scheduling starts with the following command.

crontab -e

Generally the command opens a Schedule file in VI Editor. Then write the following script in that file & save that. If you aren’t familar with VI Editor then visit http://www.cs.colostate.edu/helpdocs/vi.html

SHELL=/bin/bash

PATH=/sbin:/bin:/usr/sbin:/usr/bin

MAILTO=root

HOME=/

1. ._____________ minute (0 to 59)

1. |  .___________ hour (0 to 23)

1. |  |  ._________ day of month (1 to 31)

1. |  |  |  ._______ month (1 to 12) OR (jan to dec)

1. |  |  |  |  ._____ day of week (0 to 6) (Sunday=0 or 7)  OR

1. |  |  |  |  |      sun,mon,tue,wed,thu,fri,sat

1. |  |  |  |  |

1. *  *  *  *  *  command to be executed

1 12 *  *  *  cp /file1 /file2

The script is self descriptive as the comments of the script explains the operation. Finally

service crond restart

Customize the script to schedule your own tasks. That’s all, Enjoy!!

How to Activate Windows 7

Three Easy Steps should be followed to activate Windows 7.

• Download the crack from here.
• Open Windows 7 Loader.exe & Click Install button.



• Restart your windows 7 & Check Status (window+pause/break).

That’s all. You may checkout “Advanced options”. The Crack works with any versions of Windows 7 (as the developer claimed). , Enjoy!!
The Credit of the Post goes to Chinmoy Barman Spandan, my lil bro 🙂

How to download Torrent via Proxy

We can download files from torrent via proxy server if proxy server/firewall allows non standard port for TCP communication. The following steps should be followed.

• Install\Update to latest µTorrent build.
• Ensure ports are forwarded for bit torrent  (non standard port recommended).
• Options >> Preferences >> Advanced >> bt.transp_disposition set to 255
• >> Bit Torrent > Protocol Encryption > Outgoing: Forced >> Check Allow Legacy Connections.
• >> Connection >> Set µTorrent forwarded port.
• >> General >> Associate µTorrent associations >> Install IPV6.
• Click OK.
• Vista/Windows 7:  Goto Start > Run, write  services.msc & Run.
• Set IP Helper Service to Automatic and ensure it is started.
• Restart µtorrent, ensure port is forwarded.

That’s all, ENJOY!

Determine Google PageRank via PERL

We can determine Google PageRank with a code of 3 lines in PERL. You need to install WWW::Google::PageRank, download from here. The script is as follows

#!/usr/bin/perl
use WWW::Google::PageRank;
my $pr = WWW::Google::PageRank->new(proxy => ‘http://A.B.C.D:Port/’);
print scalar($pr->get($ARGV[0])), “\n”;

Usage: perl <script_name> <static_URL>

If you use no proxy then delete “proxy => ‘http://A.B.C.D:Port/'&#8221; otherwise mention the Proxy IP address & Port. The script returns an integer as PageRank (Higher is better). That’s all, Thanks.

How to Install Internet Information Services (IIS 7) on Windows 7 Ultimate

If you want to install Microsoft Internet Information Server (IIS 7) on your new Windows 7 computer first time after working with IIS 6 for long years, I believe you will be surprised with the improvements and changes both in IIS and IIS installation process.

First of all Microsoft has renamed the IIS as Internet Information Services and is not now using Internet Information Server for IIS.
In this short guide I will summarize the steps of installing IIS 7 on Windows 7 in the way I had recently on my Windows 7 Ultimate Edition PC. I’m using this pc as a home pc but I work on my web projects at home so I run SQL Server 2008 R2 as well as IIS and host ASP.NET applications.

So if you want to install Internet Information Services (IIS 7) for a developer computer then you can follow me by reading my notes below.
I do not know the other editions but Windows 7 Proffessional edition and the Windows 7 Ultimate edition are able to install and run IIS 7.

IIS Installation

IIS 7 can be installed and features of IIS 7 can be added or removed by Windows 7 “Control Panel > Programs” management screen. You can add and install Windows 7 components and build in applications using the “Turn Windows features on or off” link.

When the Windows Features screen opens and generates in a short time a list of Windows 7 features installed and configured on the current system and a list of Windows 7 features not installed yet.
When the list is completed drill down the Internet Information Services node.

Internet Information Services – IIS 7 World Wide Web Features

Application Development Features

I started with the World Wide Web Services and Application Development Features.
Since I’m an ASP.NET developer and aim to work with ASP.NET on IIS 7, I selected the checkbox next to ASP.NET. When you click on ASP.NET the following features will be automatically selected :

• .NET Extensibility,
• ISAPI Extensions and
• ISAPI Filters.

Security

Then I opened the Security node and marked Windows Authentication beside Request Filtering.
I did not choose any other options since I do not think to develop using other authorization and authentication features in a short time.
So I keep them uninstalled. I can installed these features in future somehow.

Common HTTP Features

From the Common HTTP Features, I choosed Static Content in order to serve static web pages in .htm and .html file extensions.
I did not select Directory Browsing feature to install as you will see, since directory browsing function is one of the basic ones that we remove from each web site on IIS 6 or other IIS versions.
I do not prefer to work with WebDAV now, so I keep WebDAV Publishing feature unchecked too.

Health and Diagnostics

From the Health and Diagnostics tools you will find new logging, monitoring and tracing tools helpful for keeping your web server secure. The Request Monitor and Tracing features will also help you to debug your applications by tracing the web request easily.

Performance Features

In the IIS 7 Performance Features section there exists compression functions for static content and dynamic content. You can choose any compression feature.

Internet Information Services – IIS 7 Web Management Tools

The IIS Management Console is a must if you are working with Internet Information Services. It is a handy web management platform which contains tools and serves methods for you to publish, manage, trace and log your web sites and web applications.

I checked the IIS Management Scripts and Tools. I believe these tools and scripts will make my life easier while working on IIS 7.

IIS Management Services is used to perform management of Internet Information Services from remote computers. If you want to perform management of your web server from remote computers, you should mark this option. Especially if you are installing IIS 7 on a web server, probably you will want to remote manage your IIS web server.

After you select all the necessary components, tools and features required for you click on OK button to start installing IIS 7 on Windows 7.
You will have wait for a few minutes while Windows 7 is installing IIS 7 and changing IIS 7 features.

After the Internet Information Services – IIS 7 installation is completed you can browse to the http://localhost in order to see if your IIS7 is installed and start running on your Windows 7 computer.
If IIS7 (Internet Information Services) is up and running the following static web page will be displayed on your browser.

You can open the Internet Information Services (IIS) Manager console by following the below path.

Open “Control Panel > System and Security > Administrative Tools” then click on Internet Information Services (IIS 7) Manager icon to open the IIS 7 management console.

I believe web developers and IIS administrators installed IIS before will not face difficulty installing IIS 7 on Windows 7

Activating Root Account in Fedora 12

The procedure of Activation of Root account in Fedora 12 defers from other fedora distributions & can be possible by following the easy steps.

• Logged in as any non root user & open Terminal.
• Write “su” & press Enter, then enter the root password.
• Then open /etc/pam.d/gdm in gedit.

gedit /etc/pam.d/gdm

• Block the following line using ‘#’ sign in front of it.

auth       required    pam_succeed_if.so user != root quiet

• Save the file & exit.
• Then open /etc/pam.d/gdm-password in gedit.

gedit /etc/pam.d/gdm-password

• Block the following line using ‘#’ sign in front of it

auth       required    pam_succeed_if.so user != root quiet

• Save the file & exit.

That’s all. Logged out from current non root account & Now you can log in as root in Fedora 12.

Infix Calculator in yacc and flex

Calc.yacc

%{
#include "stdio.h"
#include "math.h"
#define YYSTYPE double
YYSTYPE last_value = 0;
extern int yylex(void);
%}
%token NUMBER
%token LAST
%left '+' '-'
%left '*' '/'
%left '^'
%left NEGATIVE
%left COS EXP SIN SQRT TAN
%%list:
| list '\n'
| list expr '\n' { printf("%.8g\n",last_value=$2);
}
;
expr: term { $$ = $1; }
| expr '+' expr { $$ = $1 + $3; }
| expr '-' expr { $$ = $1 - $3; }
| expr '*' expr { $$ = $1 * $3; }
| expr '/' expr { $$ = $1 / $3; }
| expr '^' expr { $$ = pow($1,$3); }
| '-' expr %prec NEGATIVE { $$ = - $2; }
| COS term { $$ = cos($2*3.141592654/180); }
| SIN term { $$ = sin($2*3.141592654/180); }
| SQRT term { $$ = sqrt($2); }
| TAN term { $$ = tan($2*3.141592654/180); }
;term: NUMBER { $$ = $1; }
| LAST { $$ = last_value; }
| '(' expr ')' { $$ = $2; }

;
%%
#include "stdlib.h"
#include "string.h"
#include "unistd.h"
int lineno;
char *fname = "-stdin-";
int yyerror(const char *s)
{
fprintf(stderr,"%s(%d):%s\n",fname,lineno,s);
return 0;
}
main()
{
yyparse();
return 0;
}


Calc.flex

%{
#include "stdio.h"
#include "unistd.h"
#include "stdlib.h"
#include "math.h"
#define YYSTYPE double
#include "y.tab.h"

extern int lineno; /* current line number */
extern YYSTYPE yylval; /* value of numeric token */
%}

digit [0-9]
space [ \t]

%%

{space} { ; } /* spaces are ignored */
{digit}+\.?|{digit}*\.{digit}+ {
yylval = strtod(yytext,0);
return NUMBER; }
\*\* { return '^'; }
last { return LAST; }
cos { return COS; }
exp { return EXP; }
sin { return SIN; }
sqrt { return SQRT; }
tan { return TAN; }
pi { yylval = atan(1.0)*4;
return NUMBER; }
e { yylval = exp(1.0);
return NUMBER; }
\n { lineno++; return '\n'; }
. { return yytext[0]; }
%%

How to Compile & Run:
Open Terminal, then

[root@Srijon Desktop]# yacc -d Calc.yacc
[root@Srijon Desktop]# flex Calc.flex
[root@Srijon Desktop]# g++ lex.yy.c y.tab.c -ll
[root@Srijon Desktop]# ./a.out

That’s it. ENJOY!!!!!!!!