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  1. 27 Jan, 2022 3 commits
    • Pekka Paalanen's avatar
      octave: add transfer_function_lut1d_error_taps.m · d350bd2c
      Pekka Paalanen authored 
      

This script plots the maximum absolute error versus number of taps, when
you are approximating a transfer function with a 1D LUT using a given
number of taps.

This shows that increasing the number of taps has diminishing returns,
especially for pure power-law inverse functions, while the approximation
error remains relatively high even for 8-bit values.
Signed-off-by: Pekka Paalanen's avatarPekka Paalanen <pekka.paalanen@collabora.com>
      d350bd2c
    • Pekka Paalanen's avatar
      octave: add transfer_function_lut1d_error.m · 188876f5
      Pekka Paalanen authored 
      

This script plots an inverse EOTF as both original and as a 1D LUT
approximation, and the error between.

This makes it quite obvious why inverse EOTF is much harder to
approximate with a 1D LUT than EOTF: near zero, inverse EOTF is very
steep yet it quickly becomes gradual. The same behavior is not observed
at the other end near one.
Signed-off-by: Pekka Paalanen's avatarPekka Paalanen <pekka.paalanen@collabora.com>
      188876f5
    • Pekka Paalanen's avatar
      octave: add transfer_function.m · e6c81303
      Pekka Paalanen authored 
      

Add an Octave function for evaluating various transfer functions by
name. The script transfer_function_roundtrip_check acts as the test
suite for it. For now, only AdobeRGB, sRGB, and traditional gamma
function are supported, more transfer functions can be added later. The
identity function does not really have a use yet, it is just for
convenience.

GNU Octave is a "scientific programming language" that makes it
relatively easy to implement numerical algorithms and draw graphs.
Sharing a library of color related scriptable code should help people
with mathematical experiments around color and HDR.
Signed-off-by: Pekka Paalanen's avatarPekka Paalanen <pekka.paalanen@collabora.com>
      e6c81303
  3. 20 Dec, 2021 1 commit
    • Pekka Paalanen's avatar
      A Pixel's Color · a19c35a8
      Pekka Paalanen authored 
      

Add a story on what one would need to know to process and display a
pixel.

This is an introduction to people who are already familiar with computer
graphics in general, images in memory, and maybe window systems, but
never really thought what the values in a pixel actually mean or what
they are doing wrong with them.
Signed-off-by: Pekka Paalanen's avatarPekka Paalanen <pekka.paalanen@collabora.com>
      a19c35a8
  5. 10 Nov, 2021 1 commit
  7. 20 Oct, 2021 6 commits
  9. 14 Oct, 2021 1 commit
    • Pekka Paalanen's avatar
      Drop cargo-culted copyright statements · 1c402449
      Pekka Paalanen authored 
      None of these copyrights apply to any files in this repository.

Copyright lists in FOSS projects tend to be always out-of-date when
compared to what law says about when copyright forms. Law also requires
interpretation case by case whether something is copyrightable or not.
Hence, if someone bothered to add a copyright line then they surely
expect to hold some copyrights in the works, so any such list would be
the minimum of possible copyrights holders.

All the files remaining in this repository right now were written from
scratch well after any of the listed copyright years, so the listed
copyrights cannot be true. The history can be found in
wayland/wayland-protocols!14 .
To avoid confusion, they are removed.

The license text itself has unknown copyrights according to
https://opensource.org/licenses/MIT

Signed-off-by: Pekka Paalanen's avatarPekka Paalanen <pekka.paalanen@collabora.com>
      1c402449
  11. 12 Oct, 2021 2 commits
  13. 28 Sep, 2021 1 commit
  15. 24 Sep, 2021 18 commits