Resources on Ansel

Color theory readings

Mon, 20 Mar 2023 00:00:00 +0000

What resources can be found online and in libraries to help understand some color theory ?

Common misconceptions

Thu, 19 Jan 2023 00:00:00 +0000

This page addresses most of the mistakes and misconceptions about Ansel that can be found online.

The mathematics of diffuse or sharpen

Sun, 15 Mar 2026 00:00:00 +0000

This article documents the mathematics currently implemented in Ansel’s diffuse or sharpen module, as found in src/iop/diffuse.c, src/common/bspline.h, data/kernels/diffuse.cl, and data/kernels/bspline.cl. It is not a usage guide. It is a reconstruction of the numerical model from the source code, with the scientific claims traced back to the references cited in the code comments.¹

The mathematics of highlight reconstruction by guided laplacians

Fri, 10 Jul 2026 00:00:00 +0000

This article presents the mathematics of Ansel’s guided laplacians highlight reconstruction — the method behind the _highlight reconstruction module (src/iop/highlights.c, data/kernels/basic.cl, src/common/bspline.h). It starts from first principles, derives the reconstruction and its optimization objective, and validates it numerically on synthetic images. The scientific claims trace back to the references cited in the code and to the original design report on the pixls.us forum.¹ It describes the method as it is meant to work; a magnitude-recovery bug in the current implementation — found during the numerical validation — is documented in the closing section.²

Color management for Linux users

Wed, 24 Jun 2026 00:00:00 +0000

Linux is still vastly lagging behind MacOS and even Windows when it comes to ensuring the consistency of colors displayed on the monitor. The widely forced adoption of Wayland graphic server in most Linux distributions has damaged this state even more, since color management has been long refused by Wayland developers. The specification for a CMS in Wayland was finally drafted in 2020 and the code was merged into upstream Wayland in 2025, by external contributors, and after a long battle from the developers of earlier CMS software against the historical developers of Wayland.¹ Since then, the state of CMS support is very hit-and-miss across desktop environments and distributions. And yet, the preliminary results of Ansel telemetry show 67 % of Wayland adoption among Ansel users.

Supported cameras and formats

Tue, 22 Apr 2025 00:00:00 +0000

This page lists all the known cameras and whether or not their raw files are decoded by Ansel, as well as all file types supported in input and output.

Cameras

Introduction

Some cameras may use different encoding formats (12 bits, 14 bits, sRAW, compressed or not) and image ratios (4:3, 16:9, 3:2). Because one or more of these formats is supported doesn’t imply they all are. Different cameras may share the same sensor and electronics, even though their commercial name is different: those will be found in the aliases columns.

White balance(s)

Thu, 05 Dec 2024 00:00:00 +0000

We all know what “white” is. We can picture a white sheet of paper. We know it is white because we learned it. But if you put your paper sheet under a summer sun, or a cloudy sky, or at home with those warm living-room bulbs, that white will change color. It might disturb you for the first few seconds, then you will just forget about it: your brain will adapt. But adapt (to) what ?

Troubleshooting color issues

Mon, 15 Jul 2024 00:00:00 +0000

This will apply to upstream Darktable as to Ansel since they share most of their color pipeline. The following procedure will help you troubleshoot your color issues, whether it is inconsistent appearance between export vs. preview, or between screen vs. print, or between 2 apps.

Setup your desktop properly

The inherent problem of color is it exists only as a perception, and that perception is highly contextual and fluid. If I take any color patch and display it over a white, middle-grey or black background, it will not appear the same even though a colorimeter would confirm it’s the exact same color. I have built a little web animation to showcase this effect, displaying sRGB gamut slices at constant hue, over user-defined background lightness : the sRGB book of color .

Color lexicon

Wed, 20 Mar 2024 00:00:00 +0000

mindmap
root((COLOR))
color appearance model
uniform color space
chromaticity
U, V
a, b
lightness
L
delta E
chromatic adaptation transform
illuminant
color reproduction index
color temperature
surround lighting
background lightness
dimensions
Munsell
hue
chroma
value
natural color system
blackness
saturation
hue
CIE
lightness
brightness
saturation
chroma
colorfulness
hue
measure
colorimetry
tristimulus
sensor
Luther-Ives criterion
metamerism
dynamic range
noise
mosaicing
Bayer
XTrans
zipper artifacts
spaces
rgb(RGB)
HSV
HSL
LMS
Yrg
XYZ
Yxy
Yuv
Ych
CYM
CYMK
primaries
cone cells
LED
ITU BT.Rec 709
ITU BT.Rec 2020
DCI P3
inks
spectrometry
light spectrum
wavelengths
energy
photometry
luminance
correction
profile
matrix
lookup table
transfert function
color grading
ASC CDL
channel mixer
curves
white balance

Translated from English by : Automatically generated. In case of conflict, inconsistency or error, the English version shall prevail.