Darktable : Open Source/Free Adobe Lightroom for Ubuntu

Darktable is an open source photography workflow application and RAW developer. A virtual lighttable and darkroom for photographers. 

Darktable is an Open Source application that's equal to Adobe Lightroom, this is an other interesting FOSS project that focus on Graphic processing which ability to develop (process) raw images and enhance them. Darktable interface is really good and easy to understand besides of it's contain of many production tool (image operation, white balance, exposure control, tone mapping), plugin and effect which can use it.

This application is fully safe for a beginner, all editing process is fully non-destructive and only operates on cached image buffers for display. The full image is only converted during export.

Darktable Features
Currently darktable version provider a 38 image operation plugins, besides of some features that I've mention above, here list of Plugins and effect that can use taken from its website :

Color image operations:

• overexposed: This module is a useful feature that displays pixels outside dynamic range.
• velvia: The velvia module enhances the saturation in the image; it increases saturation on lower saturated pixels more than on high saturated pixels.
• channel mixer: This module is a powerful tool to manage channels. As entry, it manipulates red, green and blue channels. As output, it uses red, green, blue or gray or hue, saturation, lightness.
• color contrast
• color correction: This module can be used to modify the global saturation or to give a tint.
• color zones: This module allows to selectively modify the colors in your image. It is highly versatile and allows every transformation possible in the LCh colorspace.

Effects/artistic image post processing:

• framing: This module allows you to add an artistic frame around an image.
• split toning: Original split toning method creates a two color linear toning effect where the shadows and highlights are represented by two different colors. darktable split toning module is more complex and offers more parameters to tweak the result.
• vignetting: This module is an artistic feature which creates vignetting (modification of the brightness/saturation at the borders).
• watermark: The watermark module provides a way to render a vector-based overlay onto your image. Watermarks are standard SVG documents and can be designed using Inkscape. The SVG processor of darktable also substitutes strings within the SVG document which gives the opportunity to include image-dependent information in the watermark such as aperture, exposure time and other metadata.
• soften: This module is an artistic feature that creates the Orton effect also commonly known as softening the image. Michael Orton achieved such result on slide film by using 2 exposures of the same scene: one well exposed and one overexposed; then he used a technique to blend those into a final image where the overexposed image was blurred.
• grain: This module is an artistic feature which simulates the grain of a film.
• highpass: This module acts as highpass filter.

find more information about darktable feature here

Install darktable in Ubuntu
How to install darktable is simply easy, Darktable has available in PPA so you can install trought it, do as follows :

• sudo apt-add-repository ppa:pmjdebruijn/darktable-release-plus
• apt-get install darktable exiv2

Darktable in action

Comparison : Darktable an Adobe Lightroom
Actually, I have never compare it directly, but someone in youtube has a brief explanation regarding to it, see following video to see the comparison of Darktable and Adobe lightroom to do such RAW photo editing. (this video is taken from youtube that's belong to TutorialGeek )

Source