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:

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.

the purpose of the basecurve is to make the otherwise scene-referred linear (linear raw rgb) color look good on your output devices. this is done independently of any color managed transforms which are also done in the pipeline, so we can establish a certain look independent of the devices. this will affect how highlights and shadows are balanced against each other, the overall contrast of the image, as well as color saturation.

Pascal recorded some new screencasts using the latest stable version of darktable, 1.0.4. The first is (one can start speaking of “as usual”) dedicated to the changes and new features of darktable 1.0, giving an overview over improvements, new UI elements and workflow changes. The second one is a bit more general. Pascal elaborates on raw file archiving and backups, about the pros and cons of DNG and Vendor formats and whether you want to embed your metadata or not.

Mukund Sivaraman from banu.com held an interesting interview with Richard Hughes, the maker of the ColorHug colorimeter: The ColorHug is a colorimeter that can be used to calibrate computer displays. It was created by Richard Hughes (hughsie). It is a fully open hardware project, and the design, drivers and firmware are available on the Gitorious code hosting website. Read the full interview here: https://banu.com/blog/41/interview-of-colorhug-maker-richard-hughes/ Thanks to Mukund for the excerpt!

Pascal de Bruijn wrote an extensive article about color management on Linux systems, covering basic explanations as well as the description of some tools. There seems to be a lot of confusion about what color management is, what it is supposed to do, and most particularly how to use it on Linux. Find the article here: https://encrypted.pcode.nl/blog/2012/01/29/color-management-on-linux/