Darktable 1.2 RAW converter
Image Processing
After selecting an image, head to the darkroom for editing (Figure 5). Again, Darktable splits the window into three areas: The left sidebar contains information about the current image, and the right sidebar is for selecting and applying the tools. In the context of Darktable, these are known as "modules."

Darktable is among the best software the image processing world has to offer today. And, it's no coincidence that many of the developers are employed in image processing research [5]. Darktable 1.2 offers around 50 tools sorted into five groups. All of these tools can be accessed via the right panel, but by default, you only see a title bar with multiple switches. The switches enable the tool and create and restore default settings; some modules also allow "multiple instances actions." In most cases, a menu defines important presets and your own presets after you have saved them (Figure 6).

The equalizer is one of the most important tools when it comes to sharpening images or improving their brilliance (clarity). The filter has a number of useful presets that indicate the bandwidth of this tool. Additionally, you can manually modify the lightness (luma), color saturation (chroma), and sharpness in the tool window. To do this, use the mouse to modify the control line in the window so that the desired effects occur. If you lift the line at the right edge, it also improves the sharpness.
Tool Groups
The basic group includes white balance, demosaic, exposure, orientation, base curve (corrects sensor characteristics), crop and rotate, and shadow and highlight tools.
The tone group contains tools for tone mapping, contrast (tone curve), and local contrast, as well as fill light to brighten shadows. The levels tool affects the entire exposure. Using three pipettes, you can select the whitepoint, blackpoint, and greypoint in the image; Darktable then adjusts the exposure accordingly. A special variant of this tool is the zone system.
The color group facilitates color processing and lets you select an input color profile and adjust an output color profile. Additionally, tools for color contrast, color zones, and color correction are available, as well as the vibrance tool and the similar (but less subtle) velvia tool. The channel mixer lets you mix colors or create monochrome images by setting the destination to gray. The monochrome tool has fewer features.
In many of these tools, it is not easy to see and understand the effects. Help is available in the form of new, enlarged snapshots that clarify the effects. To find this function, go to the top of the left panel. The take snapshot button grabs a snapshot, which you can then in display at any time in the image window by clicking. Then Darktable splits the window horizontally or vertically into two areas of equal size that show the current image and the snapshot. You can use the mouse to adjust size allocation and direction (Figure 7).

In the correction group you will find both the equalizer referred to earlier and other tools for making important adjustments, including noise removal at different levels (raw denoise) together with a denoise (profiled) tool for camera-specific noise, as well as non-local mean value and bilateral filter denoising. Also, distortions caused by the lens (lens correction), hot pixels, spots, and chromatic aberrations can be cleaned up here.
The final group of utilities, in the effect group, are not absolutely necessary; but, they are often useful and could save you a lot of work. For example, you can embed watermark, employ framing, try your hand at vignetting, or simulate a film grain. Other options are highpass and lowpass filters, a soften effect to blur your image, and fun effects like lowlight vision or bloom, which boosts highlights. A colorize function (like the GIMP filter) and a gradient filter graduated density round off the selection.
The filters [6] in Darktable applied to RAW images will produce better results than you could achieve by filtering images after conversion to a bitmap format. Thus, it is often a good idea to create and export multiple versions of an image with the filters provided by the RAW converter; then further processing can then be done in GIMP.
Conditional Blending and Masks
Layers, as used in GIMP and other graphics programs, can be computed against one another in layer modes, thus achieving special effects. Darktable has added this concept to version 1.2 and provides it for almost all filter modules with the conditional blend option (only, if..). This gives you access to the same modes as in GIMP, as well as some additional ones.
However, all filter modules today also have an option to that lets you apply them to specific sections of an image. After a lengthy discussion, the Darktable programmers developed a very effective mask model that differs from that in GIMP [7]. Depending on the filter, you create a mask in LAB, HSV, RGB, or any other color model.
The exact shape can be adjusted using several controls and then blurred to avoid hard – and thus clearly visible – boundaries. Two switches help create the mask: The eye icon disables the mask temporarily, and the symbol next to it tells Darktable to display the current mask as a yellow film in the image (Figure 8).

« Previous 1 2 3 Next »
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you've found an article to be beneficial.
News
-
The GNU Project Celebrates Its 40th Birthday
September 27 marks the 40th anniversary of the GNU Project, and it was celebrated with a hacker meeting in Biel/Bienne, Switzerland.
-
Linux Kernel Reducing Long-Term Support
LTS support for the Linux kernel is about to undergo some serious changes that will have a considerable impact on the future.
-
Fedora 39 Beta Now Available for Testing
For fans and users of Fedora Linux, the first beta of release 39 is now available, which is a minor upgrade but does include GNOME 45.
-
Fedora Linux 40 to Drop X11 for KDE Plasma
When Fedora 40 arrives in 2024, there will be a few big changes coming, especially for the KDE Plasma option.
-
Real-Time Ubuntu Available in AWS Marketplace
Anyone looking for a Linux distribution for real-time processing could do a whole lot worse than Real-Time Ubuntu.
-
KSMBD Finally Reaches a Stable State
For those who've been looking forward to the first release of KSMBD, after two years it's no longer considered experimental.
-
Nitrux 3.0.0 Has Been Released
The latest version of Nitrux brings plenty of innovation and fresh apps to the table.
-
Linux From Scratch 12.0 Now Available
If you're looking to roll your own Linux distribution, the latest version of Linux From Scratch is now available with plenty of updates.
-
Linux Kernel 6.5 Has Been Released
The newest Linux kernel, version 6.5, now includes initial support for two very exciting features.
-
UbuntuDDE 23.04 Now Available
A new version of the UbuntuDDE remix has finally arrived with all the updates from the Deepin desktop and everything that comes with the Ubuntu 23.04 base.