Gradation Curves

An updated version of Alexander Nagiller's Gradation Curves filter for VirtualDub. Additional documentation can be found in the filter's original homepage.

This version adds 64-bit support and a cross-platform AviSynth+ plugin.

Usage

VirtualDub

See the original Readme.

AviSynth

AviSynth+ 3.7.1 or newer is required.

Gradation(clip clip, string process, string curve_type [, array points] [, string file, string file_type] [, bool precise])

• clip clip = (required)

  Input clip. It must be RGB32 unless precise=true, in which case all RGB/A formats are supported.

• string process = (required)

  Processing mode. It must be one of:

  • "rgb": RGB only. It processes the image by the common RGB channel. Any edited color channel will be ignored.
  • "full": RGB + R/G/B. It processes the individual color settings first and then applies the RGB settings.
  • "rgbw", "fullw": Weighted modes. They differ from the non-weighted ones in the way RGB is processed. First a Y (gray) value of each pixel is calculated. Then the output value of the RGB curve of this Y (RGB input) value is taken and applied to all three components of the pixel the same way.
  • "yuv", "cmyk", "hsv", "lab": It processes each channel individually.

• string curve_type = "spline"

  Determines how the filter curves are drawn. This parameter is only meaningful when points is provided or when the curves file pointed to by file does not imply a draw mode itself (as is the case of .acv files). It must be one of:

  • "linear": Straight lines will be drawn between the points.
  • "spline": A spline interpolation will be applied for the given coordinates.
  • "gamma": This mode can be used to apply a gamma correction.

• array points = Undefined()

  If provided, it must be an array of lists of points structured in the following way:

  points=[
  \   [[0, 0], [3, 10], [255, 255]],  /* points for channel 1 */
  \   [],                             /* points for channel 2 */
  \   [[0, 20], [240, 255]]           /* points for channel 3 */
  \   ]

  If no list of points is provided for some channel, an empty list is assumed. An empty list of points is treated like [[0, 0], [255, 255]].

  The channels for each processing mode are:

  • "rgb", "full", "rgbw", "fullw": RGB, R, G, B
  • "yuv": Y, U, V
  • "cmyk": C, M, Y, K
  • "hsv": H, S, V
  • "lab": L, A, B

  If points is missing, file must be provided instead.

• string file = Undefined()

  If provided, it must be a path to a curves file.

• string file_type = "auto"

  Used along file. It specifies the curves file format, It must be one of:

  • "auto": Autodetect according to file extension. Supported formats are .amp, .acv, .csv, .crv, .map.
  • "SmartCurve HSV". Must be specified manually since it also uses the .amp extension.

• bool precise = false

  Use floating-point precision (slower) instead of integer math.

  This is currently only supported for the "rgb", "full", "yuv" and "hsv" processing modes.

Build

CMake

CMake can be used to build both the VirtualDub and AviSynth+ filters. The VirtualDub filter is only available on Windows.

On Unix-like systems:

cmake . -B ./build -DCMAKE_BUILD_TYPE=Release
cmake --build ./build
# Binary:
# ./build/libgradation-avs.so

On Windows:

cmake . -B ./build # Add '-A x64' (64-bit) or '-A Win32' (32-bit) to override the default architecture.
cmake --build ./build --config Release
# Binaries:
# ./build/Release/gradation-avs.dll
# ./build/Release/gradation.vdf