Following the success of our 25 killer apps for Linux post, we've dug deep to find the 20 must-have apps you should get your hands on today. Believe us when we say that for Linux users, they're indispensable.

Graphics

LightZone works according to ansell adams' theories of light and shade


LightZone 3.4

www.lightcrafts.com/linux
This powerful photo editing tool enables you to adjust the lighting attributes for any photo. Its main strength is that it uses a 'smart' editing design, in which there's typically one slider to adjust exposure settings, high dynamic range light sources, add sepia tones and make hundreds of other tweaks to a photo to improve it – or just make it look more creative. With dark photos, LightZone works wonders by enhancing the tones in the photo and brightening every pixel without giving the photo a washed-out look. The beta is free to try, but the final download package costs £100.

Qtfpsgui
http://qtpfsgui.sourceforge.net
Long-time Linux users know that the key advantage to the operating system is that a programmer can decide to make one particular tool – usually something he or she needs in a toolbox – and release the application into the wild. Qtfpsgui is just such a tool. It enables you to experiment with high-dynamic range lighting in a photo or 3D image that might be used in a game or 3D world. The options for controlling HDR lighting are simple: adjust a slider for gamma correction, load a tonal mapping tool to adjust light sources and other variables. Then, save your work for modelling in a 3D world.

Hugin
http://hugin.sourceforge.net
Experimenting with photography can lead to some wondrous results. Hugin is a panorama photo editor that can stitch your photos together. The process works like this: when taking photos, you position the lens for each successive shot so that the right side of the current photo lines up with the left side of the next photo – you turn to the right each time you take a new shot. You don't have to be exact, since Hugin can stitch the photos together quite well, although a tripod certainly helps.

Multimedia

Renoise
www.renoise.com
Far beyond the simple mechanics of recording a sound, making an audio clip and sharing it with the world, this powerful music production studio is intended for those who want to adjust the fine frequencies of each audio track in a new composition, and don't want to get bogged down with the 'happy palette' approach of a tool such as Apple Logic Pro. Even though it runs on Linux, it supports the VST instrument libraries that began life in Windows.

There's a built-in sampler that enables you to create unique sounds, then add them to your audio timeline. A pattern editor helps you take those new sounds and make a recurring sequence. Sliders for mixing the music (panning left or right, adding EQ and changing the volume) help you created the finished work

Ceemedia is a cataloguing utility for the movies you either own or have seen

CeeMedia Movie Catalog

http://ceemedia.sosdg.org
Like Alexandria, the single-purpose utility program CeeMedia is – as the name implies – a cataloguing utility for the movies you either own or have seen (or want to see). It's an intriguing program because it enables you to add a large amount of detail about each movie, including cast and crew, a plot summary and even a mini-review.

We think a good next step in the development of CeeMedia would be to form some kind of social networking feature, so users can exchange movie ratings and reviews – similar to what Flixster.com does today. As it stands, CeeMedia is essentially a front-end database for all your video entertainment and it excels at that very specific function.

Alexandria
http://linux.softpedia.com/get/Desktop-Environment/Tools/Alexandria-3488.shtml
If your office library is overflowing with books, try Alexandria, a cataloguing utility that makes it easy to scan through book covers, track which books you have loaned out or those you might need to discard because they're just taking up space. A good source for book covers is Amazon.com, but be sure to click the image for the larger version.