About Aurélien

Photographe full-stack (maquillage, éclairage, prise de vue, retouche, programmation), chercheur/concepteur en algorithmes de traitement d'image, développeur/R&D du logiciel de retouche photo darktable et d'autres outils pour photographes numériques exigeants. Formé à la musique, à la physique classique, à l'ingénierie/conception et à la programmation. Déformé à l'épistémologie, aux mathématiques et à la philosophie. Quand j'étais petit, on m'a dit que je devrai finir par choisir entre une carrière artistique ou scientifique. J'ai fini par faire des sciences pour les arts. .
18 April 2021

The sRGB book of color

2021-04-19T15:53:22-04:0018 April 2021|Categories: Image processing|0 Comments

This page is inspired by the Munsell book of color. It aims at showing the sRGB gamut volume (all the visible colors that can be encoded as sRGB triplets), projected into a perceptually uniform lightness/chroma space (using JzAzBz color space[^1]), and sliced across hue planes. The sRGB space is the lowest common denominator of all [...]

21 March 2021

Rotation-invariant Laplacian for 2D grids

2021-03-24T14:16:00-04:0021 March 2021|Categories: Calculation|0 Comments

NOTE : this article is a work in progress and not finished yet. ## Introduction The Laplacian operator $\Delta u$ is the divergence of the second-order partial derivative $\nabla^2 u$ of a multivariate function, which represents the local curvature of this function. This operator is widely used for edge-detection[^1], as well as in [...]

16 March 2020

Bilinear interpolation on images stored as Python Numpy ndarray

2020-04-01T11:10:54-04:0016 March 2020|Categories: Image processing|Tags: , |0 Comments

If you are working in image processing and using Python as a prototyping script language to test algorithms, you might have noticed that all the libs providing fast image interpolation methods (to either sub-sample or over-sample) work in 8 bits unsigned integers (uint8). This is quite annoying if you are working with floating point images. [...]

17 January 2019

Derivating HDR-IPT direct and inverse transformations

2021-03-06T14:45:06-05:0017 January 2019|Categories: Image processing|3 Comments

Following my work on the filmic tonemapping, several users have reported issues with very saturated blue areas (stage spotlights, bright skies) and red areas. The grail of image processing is being able to affect colors and brightness independantly. The big conundrum of tonemapping is raising luminance without affecting perceptual colors, and, by color, [...]

5 May 2018

Make Jupyter Notebooks easy to blog in WordPress

2021-03-24T20:48:50-04:005 May 2018|Categories: Calculation|Tags: , , , , |5 Comments

I have struggled with most solutions to convert and embed Jupyter notebooks into WordPress blog posts since I use Plotly as a graphic lib, as well as many LaTeX equations and images. Finally, I had to code my way through. Here is what I did : 1. Write the jupyter notebook Nothing that you don't [...]

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