improving contrast with the local laplacian filter sometimes difficult lighting situations arise which, when taking photographs, result in unappealing pictures. for instance very uniform lighting on a cloudy day may give dull results, while very contrasty illumination (such as back lit) may require to compress the contrast to embrace both highlights and shadows in the limited dynamic range of the output device. refer to the following two shots as examples:

Have you ever over-exposed your images? Have you ever noticed that your images look flat and dull after you apply negative exposure compensation? Even though the over/underexposed warning says there is no overexposure? Have you ever wondered what is going on? Read on. the problem First, why would you want to know which pixels are overexposed, clipped? Consider this image: … Why is the sky so white? Why is the image so flat and dull?

modern sensor capture an astonishing dynamic range, namely some sony sensors or canon with magic lantern’s dual iso feature. this is in a range where the image has to be processed carefully to display it in pleasing ways on a monitor, let alone the limited dynamic range of print media. example images use graduated density filter to brighten foreground using the graudated density iop works well in this case since the horizon here is more or less straight, so we can easily mask it out with a simple gradient in the graduated density module.

[update 2016/07/31: there was a section about intermediate export to csv and manually changing that file. this is no longer needed, exporting the style directly from darktable-chart is fine now.] motivation for raw photography there exist great presets for nice colour rendition: in-camera colour processing such as canon picture styles fuji film-emulation-like presets (provia velvia astia classic-chrome) pat david’s film emulation luts unfortunately these are eat-it-or-die canned styles or icc lut profiles.

Most modules in darktable are working on changing pixels color, lightness, etc. Few modules are moving pixels and when they do they are doing it in a very constraint way like to rotate, fix the lens' distortions or remove spots. The liquify module offer more ways to move pixels around by applying some free style distortions to parts of the image. There is three tools to help doing that: point line curve Each tool is based on nodes.

For many years darktable would only run on x86 CPUs that also support at least SSE2. While that is nowadays almost everything looking like a PC it’s still limiting. Consequently Roman sat down and started work on dropping that hard requirement. While his work isn’t complete yet it’s definitely becoming useful. So with a little tweaking you can for example use the development versions on an ARM, like the Raspberry Pi.

Since many years darktable offers a versatile tool for manual perspective correction in the crop & rotate module [1]. Although the principle is simple and straightforward, there are cases where it can prove difficult to get a convincing correction, especially if no distinct vertical or horizontal features can be spotted in the image. To overcome these limitations a new “perspective correction” module has just been added that is able to automatically correct for converging lines.

Today we are happy to announce a big new feature that we will not only ship with the big 2.0 release later this year but also with our next point release, 1.6.4, which is due in about a week: even more darkroom modules! One of the big strengths of darktable has always been its varied selection of modules to tweak your image. However, that has also been one of the main points of criticism: too much, too many and too complicated to grasp.

If you overexpose a photo with your digital camera you are in trouble. That’s what most photography related textbooks tell you – and it’s true. So you better pay close attention to your camera’s metering while shooting. However, what to do when the “bad thing” happened and you got this one non-repeatable shot, which is so absolutely brilliant, but unfortunately has some ugly signs of overexposure? In this blog article I’d like to summarize how darktable can help you to repair overexposed images as much as possible.

After being in the camera our pictures deserve some love and to be shared. Every photographer will tell you the joy of having a picture in the hands. At last the pixels have taken form on a piece of paper to give birth to a photography which can be put on the wall! Though, printing is not easy, there are many technical aspects to take into account. To streamline this process darktable has been added a print module.

There is now a development branch of darktable with experimental support for raw files from many recent Fujifilm cameras. These cameras include those with the X-Trans sensor (X-Pro1, X-E1, X20, X100S, X-M1, XQ1, X-E2, and X-T1), X-Series cameras with conventional sensors (X100, X10, X-S1, XF-1, X-A1), and some from Fujifilm’s other lines (S6000fd, E550, IS-1, S3Pro, S5Pro, S5600, E900, S2Pro, S5000, S5200, S5500, S6500fd, S9500, S9600, S9600fd). Previously, darktable would fail to read RAF-type raw files produced by these cameras.

Figure 1: the gradient test image – follow the link, download and play with it in darktable People using image editors or similar (raster) graphics editors are probably familiar with histograms. You also have them in almost all digital cameras. In darktable you can find it very prominently in the top right corner of darkroom mode, but also as a backdrop of modules like levels, tonecurve and similar.

The next major release of darktable will contain multiple features that have been discussed on this blog and that will make it more powerful than ever. These new features will allow you to process your images in new and creative ways. However there is one new feature in the upcoming darktable release that is more about Digital Assets Management and simplifying your workflow: Lua scripting. Lua is a scripting language that is commonly used to add scripting capabilities to programs.

In darktable, selective editing was a long awaited feature. Our development version now allow limiting module effects to a region of the image. Remember the old times, the red light of the darkroom, the smell of the developing bath … Remember when you were using your hands or a small piece of cardboard to achieve some masking … Now you can do that in darktable. example let take this photo as an example.

I’d like to give a few words on a new module named “color mapping” that is currently under development in our master branch. This module is a rework and enhancement of the older “color transfer” module. That older module had several issues which made a migration impossible. So we leave the old one behind as deprecated (old history stack still work as before) and for all new history stacks “color mapping” should be used instead.

One of the upcoming new feature in darktable is the ability to use the same development module several times. By applying the same module multiple times and combining them with blendif it is possible to do some effects that could not be achieved previously without using external tools like the gimp. Modules that can be instantiated multiple times have a new icon in their header, next to the “reset” button. Clicking that icon will open a pop-up menu that allows you to create a new instance of the module, change the order in which the different instances are applied, or delete an instance of the module.

One of the most time consuming work for any photographer is probably the development process. Lot of time behind a computer screen to adjust the curves, the contrast, the colors, the sharpness… All these are application specific, that is, the development process done with Lightroom is not compatible with AfterShot Pro or darktable (to name just few raw processing softwares around). This makes it really difficult to move from one software to another.

… and how to get rid of it. [update 02/05/2018 The information how to create camera noise profiles is outdated please read this tutorial instead!] [update 20/12/2012: ‘how to profile your camera’ includes instructions with the new gen-profile script] [update 15/12/2012: no more recompile needed, updated the instructions in the benchmark section and how to run make.sh.] to summarize the current situation in dt: we have a lot of cool tools wrapped around great algorithms with almost all the knobs you need to get perfect results.

Geotagging module For quite some time people have asked us for a way to geotag their images from within darktable. While that is a nifty feature for sure and really helpful when you take pictures outside of a studio we always had to say something along the lines of “sorry, we don’t have that yet”. Some day however Henrik decided to give it a try and started work in his geo branch.

People following the development of darktable might have heard that we added a grouping feature. Everyone who hasn’t heard of that yet: We added a grouping feature. Now that everybody knows about it I should try to explain what it actually is and how it works/how to use it. For the technical specification you can have a look at the design specs. Grouping turned off The first change in the GUI that can be noticed is a little ‘G’ button.

in an ideal world, an image is piecewise smooth. it has soft gradients, some detail and edges. in particular there’s no noise and the edges are sharp. given these assumptions, you can do a lot of cool things to your pictures, using techniques like frequency space editing, wavelets, or local histograms. darktable’s equalizer module demonstrates some of this, using the wavelet approach. you can use it to sharpen and denoise, enhance or attenuate certain frequencies in your image, while keeping the edges intact.

darktable is all about providing you the best tools in order to get the most out of your photographies. This blog entry will explain how an existing feature can help you get more detailed exports and it will try to give you a glimpse of what is cooking in an unscheduled but upcoming version of darktable for even better detail preservation. Make sure to enable High Quality Resampling for exporting your photographies In darktable, the pixel pipeline is responsible for processing your photography from demosaic up to the point it is passed over to the output subsystem (saving in tiff, jpeg…).

or “If one slider is not enough” Diligent readers of our small blog series are already aware of the blending feature that darktable offers as part of many modules. Instead of just handing over their result to the subsequent module in pixelpipe, “blending modules” take a moment to reconsider. Based on the blend setting they will take their original output together with their input and do a re-processing. As an example refer to here, where we took blend mode “overlay” with module “lowpass” to do shadow recovery.