Helpful GIMP Tips and Tutorials

Helpful GIMP Tips and Tutorials


About GIMP and Inkscape

GIMP is a raster/bitmap graphics tool and Inkscape is a vector graphics tool. Together they meet most graphics needs in photo/image manipulation and creation of scalable graphics and offer free/open source alternatives to Adobe Photoshop and Illustrator.

Answers to Common Questions on:

  • Drawing simple shapes
  • Layer manipulation
  • Combining images and photos
  • Application of filters
  • Image Enhancement
  • Opening and Transforming Files

The first stop for new users or people seeking reference documentation should be the GIMP manual available in various languages. It is easy to read with highlights for users and plenty of pictures to indicate what you should see while using the tools.

Basics

Fading parts of images to white (or other colours)

  •  The fade effect – Fade parts of images to image or other colours via layer masks and Gaussian blur.

Making collages

Image Enhancement

These techniques can be helpful for post-processing (PP) of images and photos or highlight elements. Of course with photos it is best to take a good photo so you don’t need much PP!

  • Contrast Mask – Control contrast in an image (e.g. brighten dark areas in an image, bring out more highlights in dark areas/shadows)
  • Selective Colourization – Take a colour photograh and make certain parts of it black and white, while other parts retain their colour. This method is used to highlight portions of a photo with colour to bring attention to it, while other parts are black and white or have some other filter applied.

Text Manipulation

Opening and Transforming Files

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Resize and Expand a Virtualbox Hard Drive and Media in 4 Steps

Resize and Expand a Virtualbox Hard Drive and Media in 4 Steps


Updated April 1, 2014

Often, people find their virtual machine hard disks are too small for usage needs. Below are steps showing you how to resize and expand an existing VMDK or VDI virtual hard drive in VirtualBox for use with a guest virtual machine (VM).

Things to Know Before You Start

  • If you already have a dynamically allocated disk that is VDI or VHD linked to the virtual machine, simply use the VBoxManage modifyhd –resize command. e.x. VBoxManage modifyhd <your filename> --resize 100000. That command would be for 100GB. You can then skip to the resize your guest OS step in this guide. If you’re not sure or don’t have it, read on.
  • If your hard drive is VDI, you can try the CloneVDI tool to resize your disk easily without and skip to the resize your guest OS step in this guide.
  • There are suggestions below to help you avoid having to resize virtual drives ever again by using large dynamically expanding storage and can be completed in 10-20 minutes.
  • Ensure your guest VM is powered off before executing the steps and that all hard disks involved are not connected to VMs.

Step 1: Create a New Hard Disk

Use VirtualBox to create a new hard disk (vdi) with your desired size. You can use the dynamically expanding storage or a fixed size disk. If you are expanding the hard disk capacity, choose a size significantly larger (e.g. double the size) than the original hard disk to avoid problems.
Note: Starting with version 4.0 of VirtualBox, to create new disk images, use the “Storage” page in a virtual machine’s settings dialog because disk images are now by default stored in each machine’s own folder. The screenshot below pertains to VirtualBox 3.0.

Disk Type should be the Same

Make sure the new disk you create is of the same type as your old disk you want to expand. So if you have an IDE hard disk already, create a new IDE disk. The same applies for a SATA disk.

Recommendation: Use a large size dynamically expanding storage

It is to your advantage to use a large dynamic hard disk with a high maximum storage space to save you from having to go through this resizing process frequently. Having a dynamic 300 GB or 2 TB virtual disk won’t actually take up 300 GB or 2 TB on your hard drive and only takes up the actual disk space used on the disk. The exception to the recommendation would be if the system storing your virtual hard disks has space restrictions and your hard disks tend to grow quickly (e.g. a virtualized database server sitting on a host machine with a small hard drive).

Use of a fixed-size storage

It is best to use dynamic storage; however, some people have experienced problems using the dynamically expanding storage and using the fixed-size storage solved their problems.

Step 2: Clone Your Old Hard Disk

You can clone your old hard disk with the VirtualBox VBoxManage command. Make sure your VirtualBox directory containing the VBoxManage command is in your operating system path or you can execute the command below from the VirtualBox with absolute paths (e.g. ~/.VirtualBox/HardDisks/old_hard_disk.vdi). If you are in the directory containing your HardDisk folder (e.g. ~/.VirtualBox/HardDisks), run the following:

VBoxManage clonehd old_hard_disk.vdi new_hard_disk.vdi ––existing
Notes on using VBoxManage:

  • There are *2* dashes before ––existing.
  • The commands shown are case sensitive and should be entered as shown. VirtualBox documentation contains more info on VBoxManage and command syntax.
  • If you are running VBoxManage in Windows and are not running the command in the same directory as the hard disks you are cloning, you may have to add quotations ” ” around your hard disk paths so the command can recognize the location of the hard disks. For example:

C:Program FilesOracleVirtualBox>VBoxManage clonehd "c:extUbuntu64Studio.vdi" "C:Folder With SpaceNewHardDisk.vdi" --existing

  • Make sure to follow the syntax ordering given by the VBoxManage command, otherwise you may get an error like Invalid parameter ‘C:FolderWithSpaceNewHardDisk.vdi’.

The command will work if your old disk is in the vdi and also the VMDK format. The “–existing” parameter tells VirtualBox that the clone operation is to an already existing destination medium. Only the portion of the source medium which fits into the destination medium is copied. Since the new_hard_disk.vdi for us is larger than the old_hard_disk.vdi, all the source will be copied to the destination (e.g. entire guest hard disk).

Note for VMDK images: Your original VMDK guest image could be in one VMDK file or split into multiple VMDK files done by a virtualization program like VMWare. The advantage of having split files is it makes it easier to backup to DVDs and discs. After the cloning, you will only have one large VDI. To back up to disc media you’ll have to use a program to split the guest image (e.g. guest’s own tools or file splitters)

Cloning hard disks… you see something like the following

Oracle VM VirtualBox Command Line Management Interface Version 3.2.12
(C) 2005-2010 Oracle Corporation All rights reserved.
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Clone hard disk created in format 'VDI'. UUID: ee28ab8b-8232-4c76-8c1b-184afdd1dd27

Step 3: Update the Guest Hard Disk

Replace the old guest hard disk with your new hard disk (i.e. new_hard_disk.vdi):

  1. Go to the settings for the guest VM and choose the “Storage” options.
  2. Select the appropriate controller (e.g. IDE Controller, SATA Controller) and add your new hard disk.
  3. Remove the old hard disk from the Storage section of your guest.

Step 4: Resize the Guest File System

If you boot into your guest operating system (OS), the file system will continue to only use the old hard disk partition set up. To use the increased disk space visible the OS, you can use disk partition management commands. The steps for the resizing the disk can depend on your operating system.

For Windows environments

Windows 7, Windows Server 2008

You can boot into Windows using the new hard disk and use the “Disk Management” utility to extend your hard disk volume. Right click on the drive you are extending and select the extend command.

Windows XP, Windows Server 2003, Windows 2000

Microsoft has a good knowledge base article on partition management for these versions of windows. Alternatively, you can use this partition manager tool from Aomei which works on a variety versions of Windows.

For other environments like Linux and Mac

You can use a Gnome Partition Editor GParted boot disk / live CD to resize the disk partition so the guest file system knows about the increased disk space. To use GParted on the guest, configure the guest to boot from the GParted CD (General -> Advanced tab set CD/DVD Rom as the first boot device, then select GParted CD). Instructions for using GParted and resizing disk partitions can be found at the GParted website or Google GParted resizing for several walkthroughs.

Note on Logical Volume Management (LVM) disks / partitions (common for Fedora installations)

You can graphically manage lvm partitions using the system-config-lvm Linux tool. Documentation for system-config-lvm is available for various flavors of Linux online and a comment from David in the comments section has confirmed this method works on Ubuntu 10 Server.

If you cannot use system-config-lvm, here are other options:

  1. Try GParted. GParted currently (December 2012) has some support for lvm (source: http://en.wikipedia.org/wiki/GParted). There is no easy way to expand a partition using lvm with the file system in the logical volume as supposed to ext3 or ext4 partitions.
  2. If the lvm partition does not contain the operating system, just create a new partition using GParted with ext3 or 4 (ext3 is safe) with the new virtual disk space. Go into the OS and copy all files from the lvm to the ext partition. Remove the lvm partition later after you have confirmed the files are converted and not in use.
  3. If the lvm partition contains your operating system (root lvm), either (1) copy your key files (e.g. /home/) to a backup and reinstall the OS or (2) attempt to convert the lvm to a different kind of partition or expand it. The (2) second option’s instructions are more complex due the active root partition and other things like resizing the file system. However, if you know Logical Volume Management (LVM) administration well, you can find some instructions on the internet and comments on this article from “zuzu”.

References

Six hard disk drives with cases opened showing...

Photo credit: Wikipedia

People’s Experience with These Steps

You can find in the comment section of this article other people’s experiences with these steps and their tips.

THANK YOU Readers!

This post has been enhanced several times thanks to reader comments.

Installing VirtualBox guest additions on Fedora

Installing VirtualBox guest additions on Fedora


Happy Holidays!

This celebration season post covers installation of the VirtualBox guest additions on Fedora while using yum to update the kernel sources.

The steps were tested in Fedora 13 (GNOME), Fedora 14 (GNOME), and Fedora 15 (XFCE and KDE). A common problem in installing the guest additions on a new copy of Fedora is the guest additions install will complain about missing kernel sources. These steps show how to update the kernel sources to fix this problem and allow a successful install of the guest additions.

OS Set Up and Installation of Guest Additions

1) First update the kernel by typing following command.

yum -y update kernel 

The latest kernel will be downloaded and updated.

2) Type following command after the kernel update.

yum -y install kernel-devel kernel-headers dkms gcc gcc-c++ 

After that, restart the Fedora virtual machine (VM).

3) Go to devices in VirtualBox console and select Install Guest additions.

This action will mount the VirtualBox guest additions and it will be visible on your desktop if it mounted successfully. Alternatively, you can find it in the file system (e.g. /media/VBox Additions CD).

4) Open a console terminal. Change directory to the Vboxadditions CD and run the following command.

sudo sh VBoxLinuxAdditions.run 

Note: To run sudo you must be part of the /etc/sudoers file – e.g.

# User privilege specification
yourusername    ALL=(ALL) ALL

or part of a Unix/Linux administration group.

5) It is possible after running the VirtualBox additions that you still need to install the current kernel-devel (files used for building kernel modules) in yum. In which case, the VBox additions install will tell you what to install (see an example below). After installing the kernel-devel, try running the VirtualBox additions installation again (sudo sh VBoxLinuxAdditions).

Building the VirtualBox Guest Additions kernel modules
The headers for the current running kernel were 
not found. 
If the following module compilation fails then 
this could be the reason.
The missing package can be probably be installed with
yum install kernel-devel-2.6.32-100.28.5.el6.x86_64

Check the installation log to verify everything works.

Shared Folders

If you’re using shared folders, check the VirtualBox documentation on using them. Usually the thing you have to do after setting up your host to share folders with the Fedora guest is to add the Linux user you are using to the vboxsf user group.

for example, use the command:

usermod -a -G vboxsf your_user_name

After adding your account to the vboxsf group, logout and then login again. You should be able to access the shared folders in the /media/ folder.

Add a user to a group

Usermod is a command to change a user’s account settings.To add a user to a group, use the following:
$ usermod -a -G newGroup username
Make sure to use the -a option so the user is added to newGroup while continuing to be a member of other groups. Otherwise the user is removed from all groups and only added to newGroup.

Install LAMP on Fedora and Run in 15 minutes – Apache, MySQL, PHP, and phpMyAdmin

Install LAMP on Fedora and Run in 15 minutes – Apache, MySQL, PHP, and phpMyAdmin


Below are steps to install the LAMP stack on a Fedora Linux server – Apache HTTP Server, MySQL (database software) and PHP (or Perl or Python) in about 15 minutes.

Things to know

  • Commands below are executed as root (or prefixed with sudo).
  • The steps have been tested on Fedora 14, Fedora 15, and Fedora 16 successfully.
  • Instead of localhost for the steps below, you may have to substitute your server’s IP address (e.g. 192.168.2.31).
  • If you are using another Linux distribution (e.g. Ubuntu, OpenSUSE), the install command executions and file locations may differ, but setup will be similar.
  • If you already have the packages installed, your package manager will tell you and you can skip the installation step.
  • Install commands below will install the latest stable releases.

Getting Ready with a Clean Slate (Optional)

If you want to start with a clean install, you can remove existing installations of the components of the LAMP stack first.

# yum erase httpd mysql mysql-server php php-mysql phpmyadmin

Be careful if you do execute this command and find some components are already installed and yum asks you if you want to uninstall them. For example, some KDE distributions install MySQL with KDE packages like Akonadi, so you can leave MySQL there.

Install all Apache Web Server, MySQL, PHP, and phpMyAdmin

With this command, you can install all the packages at once.

# yum install httpd mysql mysql-server php php-mysql phpmyadmin

Apache – Starting and Configuring Apache (HTTPD)

Configure Apache to start automatically (Optional):

# /sbin/chkconfig httpd on

To start the server process immediately:

# /etc/rc.d/init.d/httpd start

Check Apache is running

Open up a browser on your server and go to the web address:

http://localhost/

You should see a web page saying that Apache is running assuming your default Apache site (/var/www/html/) is empty.

 Get Started on a Website

If you want to get started with a website in Apache, you can find the root of the web server at /var/www/html/ and configuration files at /etc/httpd/

Other notes

Instructions on how to use iptables or system-config-firewall-tui to ensure port 80 is accessible from remote computers.

MySQL – Starting and Configuring MySQL

Start MySQL first if it isn’t already started. If you skip this step, a common error encountered is Can’t connect to local MySQL server through socket ‘/var/lib/mysql/mysql.sock” or /tmp/mysql.sock.

# /etc/rc.d/init.d/mysqld start

Some Fedora installations may already have MySQL running for KDE packages like Kontact, Kmail, and Akonadi, so MySQL may already be started.

Check MySQL is running

# mysqladmin version status

Set mysql root password

Go into the mysql command line to set the root password.

mysql -u root

Set the password of the root user in mysql at the mysql prompt. Do not forget to end your mysql command with a semicolon:

mysql> SET PASSWORD FOR ‘root’@’localhost’ = PASSWORD(‘yourpassword’);

If it is successful, this message appears:

Query OK, 0 rows affected (0.00 sec)

Exit the mysql prompt

mysql> quit

PHP – Check PHP works with Apache and MySQL

Create the following file in the Apache default site.

# echo “<?php phpinfo(); ?>” > /var/www/html/index.php

Go the address below. You should see a page describing PHP’s configuration and status:

http://localhost/index.php

To see the MySQL section, go to:

http://localhost/index.php#module_mysql

If the steps above succeeded, you can delete your test file with:

# rm -f /var/www/html/index.php

Configure server start up (Optional)

To start MySQL and Apache every time the server starts up, execute the following:

# chkconfig –levels 235 httpd on

# chkconfig –levels 235 mysqld on

phpMyAdmin – Configure Apache and phpMyAdmin

If you want to allow phpmyadmin connection from other locations other than localhost, then modify the following file. This setting is not recommended if you want to restrict who can access phpMyAdmin, but is common for server installations.

nano /etc/httpd/conf.d/phpMyAdmin.conf

Comment out these lines in the file:

<Directory /usr/share/phpMyAdmin/> 
order deny,allow 
deny from all 
allow from 127.0.0.1 
allow from ::1 
</Directory>

So the lines looks like:

#<Directory /usr/share/phpMyAdmin/> 
# order deny,allow 
# deny from all 
# allow from 127.0.0.1 
# allow from ::1 
#</Directory>

Restart Apache:

# /etc/rc.d/init.d/httpd restart

Check everything is working!

Now you are all set Apache, MySQL, and PHP are setup and you have phpmyadmin to help you administer the MySQL server. Access phpmyadmin at http://localhost/phpmyadmin. Use your MySQL root credentials you configured during the MySQL set up to log in. If you can log into the phpmyadmin application, everything works – Congratulations!

Helpful links for installing LAMP

Random thought:

Turn on the LAMP in your life.