Darktable is slowly converging to a scene-referred RGB workflow. Why is that? What does it involve? How does the use of darktable change? Answers here…
This article begins with a 3 section introduction of the Lab space. You don’t need to understand it in detail in order to understand what happens next.
The color space CIE Lab
was published in 1976 by the International Commission on Illumination (CIE), in an attempt to mathematically describe the color perception of the average human being. Lab space aims to decouple the brightness information (L channel) from the chroma information (channels a and b) and takes into account the non-linear corrections that the human brain makes to the linear signal it receives from the retina. Lab space is derived from CIE XYZ space
, which represents the physiological response of 3 of the 4 types of photo-sensitive cells in the retina (the cones).
Siril
is a program for processing astronomical photographs.
In this tutorial, I’ll show you how to process a nightscape in Siril 0.9.10.
It doesn’t intend to be comprehensive tutorial but rather to present a basic general workflow that is a good starting point for those who want to learn Siril.
For this purpose, I’m sharing the raw files I used for the image I presented here
, except that for this tutorial I limited the number of frames for the sake of bandwidth and processing speed.
All photographic lenses have several types of errors. Three of them can be
corrected by software almost losslessly:
distortion
, transverse
chromatic aberration (TCA)
,
and vignetting
. The
Lensfun
library provides code to do these
corrections. Lensfun is not used by the photographer directly. Instead, it is
used by a photo raw development software such as darktable or RawTherapee. For
example, if you import a RAW into darktable, darktable detects the lens model,
focal length, aperture and focal distance used for the picture, and it then
calls Lensfun to automatically correct the photograph.
Ilya Varivchenko
is a fashion and portrait photographer from Ivanovo, Russian Federation. He’s a UNIX administrator with a long-time passion for photography that has now become a second part-time job for him. Working on location and in his studio, he’s been producing a wonderful body of work
specializing in portraiture, model tests, and more.
He’s a member of the community here (@viv), and he was kind enough to spare some time and answer a few questions (plus it gives me a good excuse to showcase some of his great work!).
Stefan Schmitz
is a photographer living in Northern France and specializing in sensual and nude portraits.
I stumbled upon his work during one of my searches for photographers using Free Software on Flickr
, and as someone who loves shooting portraits his work was an instant draw for me.
A camera profile is often a combination of a color lookup table (LUT) and a tone
curve which is applied to a RAW file to get a developed image. It translates
the colors that a camera captures into the colors they should look like. If you
shoot in RAW and JPEG at the same time, the JPEG file is already a developed
picture. Your camera can do color corrections to the data it gets from the
sensor when developing a picture. In other words, if a certain camera tends to
turn blue into turquoise, the manufacturers internal profile will correct for
the color shift and convert those turquoise values back to their proper hue.
Noise in digital images is similar to film grain in analogue photography. In
digital cameras, noise is either created by the amplification of digital
signals or heat produced by the sensor. It appears as random, colored speckles
on an otherwise smooth surface and can significantly degrade image quality.
Noise is always present, and if it gets too pronounced, it detracts from the
image and needs to be mitigated. Removing noise can decrease image quality or
sharpness. There are different algorithms to reduce noise, but the best option
is if having profiles for a camera to understand the noise patterns a camera
model produces.
There are many different approaches to blending exposures in the various projects
, and they can range from extremely detailed and complex to quick and simple.
Today we’re going to look at the latter.
I was recently lucky enough to attend an old friends wedding in upstate NY.
Mairi got married!
(For those not familiar with her, she’s the model from An Open Source Portrait
as well as A Chiaroscuro Portrait
tutorials.)
Mairi's chiaroscuro portrait.
I had originally planned on celebrating with everyone and wrangling my two kids, so I left my camera gear at home.
Turns out Mairi was hoping that I’d be shooting photos.
Not wanting to disappoint, I quickly secured a kit from a local rental shop.
(Thank goodness for friends new and old to help wrangle a very busy 2 year old.)
Peter really (ahem) throws a light on many amazing luminaries from not only the Free/Open Source Software community, but in some cases the history and roots of all modern computing.
He has managed to coordinate portrait sessions with many people that may be unassuming to a layperson, but take a moment to read any of the short bios on the site and the gravity of the contributions from the subjects to modern computing becomes apparent.
The IMAGE
team at the GREYC
research laboratory is pleased to announce the release of version 2.7 of G’MIC (GREYC’s Magic for Image Computing), its free, generic, extensible, and probably a little magical, framework
for digital image processing
.
The previous PIXLS.US article
on this open-source framework was published a year ago, in August 2018. This new release is therefore a good opportunity to summarize the main features and milestones of the project’s life over the past twelve months.
Fasten your seat belts, the road is long and full of surprises!
digiKam stores the current state of the application in the ~/.config/digikamrc file. This file keeps track of pretty much everything: from the database connection profile and custom toolbar settings, to the last-used curve and sharpening parameters. So next time you install or reinstall digiKam, don’t forget to back up the digikamrc file. This way, you don’t have to configure a fresh digiKam installation from scratch. Simply copy the file to a safe location or external storage device, and drop the file into the ~/.config folder before you run digiKam.
When it comes to Android apps for photographers, we are spoiled for choice. From depth-of-field and golden hour calculators to sun position and remote control apps – there are plenty of clever tools to choose from. But there is one particular app combination that can prove to be indispensable for any photographer on the move: a GPS logger and a GPX viewer. There are two main reasons for that.
I’ve been a member of the community over at blenderartists.org
(previously elysiun) for a long time (it’ll be 15 years this October according to my profile there
).
So it was nice to see when they finally transitioned to using Discourse
a little while back.
For years the incredible team over at G’MIC
(GREYC’s Magic for Image Computing) have been producing an incredible image processing system and many awesome filters to go along with it.
They’ve got an very active and awesome community right here on their forums
and they’ve been producing all manner of neat processing filters for photographers, digital artists, and scientists.
Due to the project being under the auspices of a French Research Lab, the GREYC
laboratory in Caen, France, they were limited in being able to accept any donations.
This year the meeting will be May 29 to June 2 in Saarbrücken, Germany
.
This is extra exciting because Saarbrücken is centrally located enough that we should have a nice representation from projects and community members.
Members of both RawTherapee
and darktable
live nearby and will be in attendance (along with others from those projects and many others).
Over on my personal website I decided to stop using third party trackers and assets
to keep from exposing visitors to unintended tracking.
Third party assets expose a user to being tracked and analyzed by those third (or fourth, or more) parties and honestly this is something the web could use a little (lot) less of.
I loved having stats early on when we started this crazy idea for a community and as I mentioned on my blog post, it’s a Faustian bargain to get stats at the expense of allowing Google to track what all the users of the site are doing.
No thanks.
It is a yearlytradition
for us to post something giving thanks around this holiday.
I think it’s because this community has become such a large part of our lives.
Also, I think it helps to remind ourselves once in a while of the good things that happen to us. So in that spirit…
We are lucky enough (for now) to not have huge costs, but they are costs none-the-less. We have been very fortunate that so many of you have stepped up to help pay those costs.
Andrea Ferrero, or as we know him Carmelo_DrRaw
, has been contributing to the PIXLS.US community since April of 2015. A self described developer and photography enthusiast, Andrea is the developer of the PhotoFlow
image editor, and is producing AppImages for:
The GIMP image manipulation program - weekly AppImage packages from stable releases and development branches.
The Hugin panorama photo stitcher - AppImages for stable releases and development branches
Andrea is the best sort of community member, contributing six different projects (including his own)! He is always thoughtful in his responses, does his own support for PhotoFlow, and is kind and giving. He has finally started a Patreon page to support his all of his hard work
. Support him now!
