Resources

Color theory readings

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

Common misconceptions

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

Supported cameras and formats

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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)

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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

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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

— 
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
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