Manage and convert color spaces

Depending on the file format and pixel format of the input and output medias, DuME tries to automatically manage and convert colors. If you need specific color profiles, you can also set you own parameters.

Color spaces in DuME

Color spaces are usually represented as three independant parameters:

  • Primaries define how the primary color of each channel should be represented. i.e. how should be represented the perfect red, green and blue colors in an RGB color space.
  • The White Point defines the exact color of what is considered full white in this color space.
  • The Transfer curve defines how the values from black to white (levels) are interpolated. It is sometimes referred as gamma but it is not exactly a gamma curve, although a simple gamma can give an approximation of this transfer curve.

In DuME, the primaries and the white point are set together with the same parameter, which means the color profiles used by DuME have only two parameters: Primaries and Transfer curve.

Apart from these parameters, the way these colors can be stored can vary according to the pixel format, which, in videos, is usually either RGB or YUV. The first describes the color as Red, Green and Blue components, and the latter as a Luma component, and two Chroma components.

DuME associates a conversion Matrix with the color spaces to convert between the YUV and RGB spaces.

Finally, when working in the YUV space, a fourth settings sets if the range is full or limited. In an 8 bit full range, values for each channel range from 0 to 255 whereas in the limited range, values are constrained to the 16-235 range.

Color profile (presets) definitions

This is the list of color profiles (i.e. presets) in DuME and their default parameters

Profile name Primaries Transfer curve Matrix Range
Images (sRGB) BT.709 / RGB / IEC 61966-2-4 sRGB / IEC 61966-2-1 RGB Full
HD Video (BT.709) BT.709 / RGB / IEC 61966-2-4 BT.709 BT.709 Limited
UHD Video BT.2020 BT.2020 10 bit BT.2020 CL Full
UHD HDR Video BT.2020 BT.2020 12 bit BT.2020 CL Full
Display P3 P3 D65 sRGB / IEC 61966-2-1 RGB Full
DCI P3 DCI P3 DCI P3 (gamma 2.6) RGB Full
Linear RGB BT.709 / RGB / IEC 61966-2-4 Linear RGB Full
PAL / SECAM PAL & SECAM / BT.470 BG / BT.601 PAL & SECAM / BT.470 M PAL & SECAM Limited
NTSC NTSC / BT.601 NTSC / BT.601 NTSC Limited

Note

This list may be adjusted in future versions.
If you feel these default values could be improved, or other ones added, please post your suggestions here.

Automatic color conversion by DuME

When all color parameters are left to their default values, here is what DuME does:

  • If the input and output pixel formats and profiles are the same, there is no conversion.
  • If one of the profiles or pixel format differ, DuME automatically converts the colors and sets the color profile, according to the following defaults.

Here are the default values used by DuME, depending on the container or the pixel format, sorted by priority.

  • OpenEXR .exr files: Linear RGB.
  • In general, all Image sequences: sRGB.
  • MP4 .mp4 or WebM .webm files: BT.709
  • h264 / AVC or h265 / HEVC encoded files: BT.709
  • QuickTime Animation / RLE encoded files: BT.709 in an RGB space.
  • RGB pixels, with 32bpc: Linear RGB
  • RGB pixels, with less than 32bpc: sRGB
  • YUV pixels: BT.709

Note

This list may be adjusted in future versions.
If you feel these default values could be improved, or other ones added, please post your suggestions here.

Input color interpretation

If DuME does not correctly detect the colors from the input media (or if they’re no standard) and the above default values do not correspond to your media file, you can set the interpretation of the input medias.

You can quickly set all values to a specific color space by selecting a preset in the options.

For any specific parameter, if you don’t know what to choose, leave it on Auto.

Output color conversion

DuME tries to automatically manage and convert the colors of the input media depending on the output format. If you need, you can force it to convert to or set a specific color space.

The first parameter “Apply” can change the way DuME manages the colors. By default, it will both convert the colors and try to set the metadata in the output file (embed color profile). You can also set it to just convert the colors, or to just add the metadata.

You can quickly set all values to a specific color space by selecting a preset in the options.

For any specific parameter, if you don’t know what to choose, leave it on Auto.