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posts by Jo

local laplacian pyramids

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:

compressing dynamic range with exposure fusion

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.

colour manipulation with the colour checker lut 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.

darktable 2.0 released

we’re proud to finally announce the new feature release of darktable, 2.0! the github release is here: https://github.com/darktable-org/darktable/releases/tag/release-2.0.0 as always, please don’t use the autogenerated tarball provided by github, but only our tar.xz. the checksums are: $ sha256sum darktable-2.0.0.tar.xz d4f2f525bbbb1355bc3470e74cc158d79d7e236f3925928f67a88461f1df7cb1 darktable-2.0.0.tar.xz $ sha256sum darktable-2.0.0.dmg 1019646522c3fde81ce0de905220a88b506c7cec37afe010af7d458980dd08bd darktable-2.0.0.dmg and the changelog as compared to the 1.6.x series can be found below. when updating from the currently stable 1.6.x series, please bear in mind that your edits will be preserved during this process, but it will not be possible to downgrade from 2.

second release candidate for darktable 2.0

we’re proud to announce the second release candidate in the new feature release of darktable, 2.0~rc2. as always, please don’t use the autogenerated tarball provided by github, but only our tar.xz. the release notes and relevant downloads can be found attached to this git tag: https://github.com/darktable-org/darktable/releases/tag/release-2.0rc2 please only use our provided packages (“darktable-2.0.rc2.*” tar.xz and dmg) not the auto-created tarballs from github (“Source code”, zip and tar.gz). the latter are just git snapshots and will not work!

released darktable 1.4.1

hi all, as most of you probably noticed already, we published a point release, 1.4.1. the tarball is here: https://sourceforge.net/projects/darktable/files/darktable/1.4/darktable-1.4.1.tar.xz/download make sure you check the signature: https://sourceforge.net/projects/darktable/files/darktable/1.4/darktable-1.4.1.tar.xz.asc/download the macintosh computer disk image with signature here: https://sourceforge.net/projects/darktable/files/darktable/1.4/darktable-1.4.1.dmg/download https://sourceforge.net/projects/darktable/files/darktable/1.4/darktable-1.4.1.dmg.asc/download this is just a point release, so not really any new features. detailed release notes are as follows: export: consistent names for output formats export to disk: overwrite file option grain plugin now allows smaller coarseness and will display coarseness values half of what they used to be, this is merely a cosmetic change, your images are unaffected.

determining focus in lighttable

wouldn’t it be great if you could judge sharpness of your images in lighttable mode? this mode is limited to small and medium sized thumbnails of your images, so we can deliver the required speed to browse a lot of them. to tell whether or not you got the focus right during the shoot, we would like to look at the full resolution. the most you get out of lighttable mode will look like this:

about basecurves

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.

have your lens calibrated!

just a quick plug for torsten’s great new service which allows you to calibrate your lens for lensfun. this will enable you to use darktable’s lens correction module with your lens if it hasn’t been calibrated by others for you yet. all you need to do is take some sample images and upload them here: http://wilson.bronger.org/calibration the page contains some more detailed instructions about which images are useful and which aren’t.

released 1.2

we released the next feature release (1.2): source tarball user manual macintosh disk image as a feature release, it comes with a lot of new goodies: profiled denoising: adapt to the properties of your camera’s sensor (72 cameras already profiled for you). lightroom import: convert some basic edits from your lightroom collection to darktable operations. multi instance support: duplicate your modules and apply them more than one time with different settings.

released 1.2rc2

we just released a new tarball for the second release candidate: https://sourceforge.net/projects/darktable/files/darktable/1.2/darktable-1.2~rc2.tar.xz/download here is the macintosh disk image: https://sourceforge.net/projects/darktable/files/darktable/1.2/darktable-1.2~rc2.dmg/download and this time it comes with an updated usermanual: https://sourceforge.net/projects/darktable/files/darktable/1.2/darktable-usermanual.pdf/download the changes on top of rc1 are minor, some details: fixed a spurious crash/deadlock when switching images in filmstrip mode fixed a couple of exif strings for profiled denoising fixed gcc 4.8.0 build new noise profiles fixed gphoto 2.5 issues updated translations updated user manual!

released 1.2rc1

we just released a new tarball for the first release candidate in the next feature release (1.2): source tarball mac disk image as a feature release, it comes with a lot of new goodies: profiled denoising: adapt to the properties of your camera’s sensor (72 cameras already profiled for you). lightroom import: convert some basic edits from your lightroom collection to darktable operations. multi instance support: duplicate your modules and apply them more than one time with different settings.

released 1.1.3

hi, there is a new point release with a couple of smaller updates. source tarball: https://sourceforge.net/projects/darktable/files/darktable/1.1/darktable-1.1.3.tar.xz/download mac disk image: https://sourceforge.net/projects/darktable/files/darktable/1.1/darktable- and the usermanual is still the same. fixes: check (on build) if glib 2.28 or higher is present don’t sanitize exif when creating hdr dngs colorpicker now disappears immediately when disabling it lens correction now uses loose lens matching (ivan tarozzi) konica minolta dynax 5d rotation fix removed an outdated assertion which could cause a crash in rare cases don’t crash when loading half-corrupted xmps don’t crash when an imported file contains incomplete gps information libjpeg-turbo workaround (klaus post) camera support: preliminary support for the new nikon d5200 white balance presets: sony alpha 700 (update to firmware v4) sony alpha 230 (new) canon eos 650d (new) canon eos rebel t2i (fixed) canon eos m (fixed) enhanced color rendition: konica minolta dynax 5d (wolfgang kuehnel) sony nex 3 (wolfgang kuehnel) sony alpha 230 (wolfgang kuehnel) sony rx100 (josef wells) darktable wouldn’t be where it is now if we weren’t able to depend on the great work of others, in particular we’d like to thank:

released 1.1.1

we released a patch release: https://sourceforge.net/projects/darktable/files/darktable/1.1/darktable-1.1.1.tar.gz/download along with an updated usermanual: https://sourceforge.net/projects/darktable/files/darktable/1.1/darktable-usermanual-1.1.1.pdf/download this resolves a couple of issues with 1.1. so no new features here, but: minor reordering of lighttable mode modules (geotagging, keywords and recent collections) cleaned up the default visible plugins when first starting darktable in most cases raw files will now show thumbnails in the import dialog (thanks to Mattias Eriksson) a curve related crash was fixed (#9906 thanks to James C.

profiling sensor and photon noise

… 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.

released darktable 1.1

https://sourceforge.net/projects/darktable/files/darktable/1.1/darktable-1.1.tar.gz/download this is a feature release, so there is a lot of new stuff: general new camera support, new whitebalance presets, etc., including canon eos m support and samsung nx fix similarity matching search for images that look alike. geotagging, complete with map view (thanks to dinamic for starting that ages ago and to houz for actually bringing it home): “ Geotagging in darktable ” mac os package: “ Bringing current darktable to OS X ” a lot of bugfixes (mainly thanks to ulrich for his meticulous work) facebook exporter (for those who have an account there) ui reworked the much hated `more plugins’ widget (thanks to boucman) image grouping: “ Grouping ” command line interface!

released 1.1rc2

i just uploaded the tarball for the second release candidate for 1.1: https://sourceforge.net/projects/darktable/files/darktable/1.1/darktable-1.1~rc2.tar.gz/download packages for your favourite distros should be in the usual place, mac dmg is here: https://sourceforge.net/projects/darktable/files/darktable/1.1/darktable-1.1~rc2.dmg/download i know there are still translations coming, but something has to be left for the final release after all :) changes since rc1 aren’t many as to be expected, but we’ve got: canon eos m support (new rawspeed, also includes samsung nx fix) usermanual is progressing two new translations (both portuguese … ;) ) reworked the much hated `more plugins’ widget (thanks to boucman) a lot of bugfixes (mainly thanks to ulrich for his meticulous work) enjoy!

1.1 release candidate 1

as commits are easing down a little lately it seems appropriate to push out the first release candidate of the new version: https://sourceforge.net/projects/darktable/files/darktable/1.1/darktable-1.1~rc1.tar.gz/download [update: mac package is available from https://sourceforge.net/projects/darktable/files/darktable/1.1/darktable-1.1~rc1.dmg/download ] That doesn’t mean this tarball is final or perfect by any means. we’ll probably go on releasing a couple of these on our way to the final release in a few weeks. This will be a feature release, as opposed to the bug fixing point release series 1.

edge aware image development

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 1.0.5 released

It’s our pleasure to announce that darktable-1.0.5 has been released. Find the tarball on sf.net: https://sourceforge.net/projects/darktable/files/darktable/1.0/darktable-1.0.5.tar.gz/download The Ubuntu PPAs have been built already, you should get them with your next update automatically if you subscribed to Pascal’s PPA. This has a good chance of being the last one in a series of stable releases (with stuff backported from our latest and greatest). Thanks to Pascal for maintaining it! As such, it comes with a short list of maintenance things as change log:

magenta highlights

false color highlights seem to be an issue frequently, so here’s some quick faq about it. alexandre, please excuse all the outward references ;) why are my highlights magenta? that’s how the sensor works. it collects a couple of photons, at some point it fills up and rejects to deliver any more useful information past this point. unfortunately that doesn’t happen at the same time for all color channels. how does the sensor work?

color correction

this is one of the oldest modules in darktable. it appeared to me that it probably lacks an example to discover how useful it can be … so here goes the example. this started off to be a wrapper around the gegl:whitebalance operation, which works in Lab color space and is able to give dark and bright colors a different color tint, interpolating between the two for mid tones. so suppose you have the following image:

bauhaus widgets

disclaimer: this is only to tease you and will not make it into the next release, but the one after … when reading gui-guidelines, most of them seem to be too general, or too specific for a certain kind of programming environment (gnome and gtk, qt, etc). for our purposes, i found the fundamental principles of the bauhaus school to be more appropriate. radical simplicity, no unnecessary shape or line, such as a pseudo 3d-bevel-border around ui elements.

why you want raw

or: how to rescue your shot after the fact. also: how to use color zones for black and white. sometimes i’m surprised by what kind of data is hidden in my raw images, and i want to pass this on to those of our users who happily take pictures in jpg. actually it’s just a short story about a typical communication problem between me and my camera and the way darktable moderates that, after the fact.

Released 0.9.3

As most of you probably noticed by now, we released 0.9.3. The tar file can be found here: https://sourceforge.net/projects/darktable/files/darktable/0.9/darktable-0.9.3.tar.gz/download Pascal updated his ppa for ubuntu here: https://launchpad.net/~pmjdebruijn/+archive/darktable-release or https://launchpad.net/~pmjdebruijn/+archive/darktable-release-plus (with Exiv2 0.22, and Lensfun 0.2.5 + lens data from svn). and made great new screencasts explaining a couple of features and differences to 0.9.2. You can find them on our resources page or Pascal’s website It is a comparatively minor update to our stable 0.

darktable and research

you might have noticed our equalizer tool, and been confused by it and the many controls. that’s probably partly because you didn’t see a similar thing before, we had to develop it first. very short history behind the ui is a powerful frequency domain processing technique, based on wavelets. the most commonly used wavelets are based on the lifting scheme [swe97], work in a data-independent way, and are decimated (i.e. the coarse coefficients are much more sparse than the fine ones).

a new caching backend

since i probably tend to make this more technical than any reader would like to, here’s the take home message: much faster import of folders much faster thumbnail creation for first-time images much improved scalability wrt concurrency much improved scalability wrt total number of images in your database (should be good up to around 500 million images) much improved robustness (no more deleting ~/.cache/darktable/mipmaps all the time, yay) some context: darktable’s light table mode shows you your image collection in arbitrary order and filtered by arbitrary queries to the underlying database.