(Optional) Apply Dolby Vision™ Creative Trims

Dolby Vision Creative Trims gives you the controls needed to adjust a target display to match the creative intent. With a valid Dolby Vision license installed, you have access to Dolby Vision L2 and L8 trims controls in the HDR FX.

The trim controls you can access depend on the Dolby Vision algorithm you are using, either Dolby Vision CMv2.9 or Dolby Vision CMv4.0.

About the Dolby Vision™ CMv2.9 Creative Trims – L2 Trim Controls

The following parameters are available when using Dolby Vision CMv2.9.

• Lift
• Gamma
• Gain
• Chroma Weight
• Saturation Gain
• Tone Detail Weight (If the Target Display is set to a 100-nit display, Tone Detail Weight has no effect and is greyed out.)

The following descriptions are from the Dolby Vision documentation from Dolby:

• Lift, Gamma, and Gain are the most common controls used to modify the shadows, midtones, and highlights of the image. In CMv2.9, these controls do not function exactly like the traditional lift, gamma, and gain controls. Instead, these three controls adjust the tone-mapping curve.

  Designed to work like traditional lift, gamma, and gain controls in the main color correction panel, these trim controls create trims that modify the shadows, mid tones, and highlight areas of the mapped image.

• Chroma Weight trim preserves color saturation in the upper midtones and highlight areas, especially when mapping down from HDR to SDR. This reduces luminance in highly saturated colors, adding detail in those areas. Chroma Weight ranges from minimum luminance with maximum saturation on one end to maximum luminance with minimum saturation on the other end. If large Chroma Weight adjustments are made at 100 nits, we recommend checking the mapping at 600 nits and adjust Chroma Weight as required.

• Saturation Gain trim enables colorists to adjust the overall saturation of the mapped image.

  Note: This Saturation Gain affects all colors in the image. To adjust saturation only for certain colors, use the saturation controls in the Secondary Trims panel (CM v4.0 only)

• Tone Detail Weight trim restores detail in the highlight areas of the mapped image. This works well in SDR by restoring some of the sharpness and details in the highlights that may be lost when mapping down from HDR to SDR.

About the Dolby Vision™ CMv4.0 Creative Trims – L8 Trim Controls

Dolby Vision CMv4.0 offers you the same creative trims as Dolby Vision CMv2.9, also known as the Primary Trims:

• Lift
• Gamma
• Gain
• Chroma Weight
• Saturation Gain
• Tone Detail Weight (In Dolby Vision CMv4.0, Tone Detail Weight is always available.)

In addition to the primary trims, Dolby Vision CMv4.0 gives you access to these additional primary trims:

• Mid Contrast Bias
• Highlight Clipping
• Mid Tone Offset: This parameter is global to all target displays of the current shot. Modifications and resetting affect all target displays of the current CM version.

The following Saturation and Hue controls are available when you are working with Dolby Vision CMv4.0, and are known collectively as Secondary Trims:

• Saturation

  • Red Channel Saturation
  • Green Channel Saturation
  • Blue Channel Saturation
  • Cyan Channel Saturation
  • Magenta Channel Saturation
  • Yellow Channel Saturation

• Hue

  • Red Channel Hue
  • Green Channel Hue
  • Blue Channel Hue
  • Cyan Channel Hue
  • Magenta Channel Hue
  • Yellow Channel Hue

The descriptions below are from the Dolby Vision documentation from Dolby:

• Mid Contrast Bias trim compresses and stretches the image around the mid tone region and can increase or decrease contrast in the mid tones of the mapped image. For more precise results, use Mid Contrast Bias adjustments with Lift or Gain.
• Highlight Clipping trim reduces or limits details in the highlights by clipping them as required, especially when the mapped image displays details that are undesirable. The resulting clipping may extend into the upper mid tones and may require some compensation using Gamma or Gain. This trim can be useful when trying to match the mapped SDR to an existing SDR Reference
• Midtone Offset is an offset to L1 mid and adjusts the image's mid-tones of the image without affecting the blacks and highlights. This global offset is per-shot and applies to all targets for the shot. This control is useful for matching the overall exposure of the mapped SDR signal to the HDR master or to an SDR reference. The changes made to this modifier are recorded as part of L3 metadata for each shot or frame of the project.
• Saturation. The six color saturation controls allow colorists to adjust the saturation of the mapped image individually across red, yellow, green, cyan, blue, and magenta, or all colors collectively when linked together.
• Hue. The six color hue controls allow colorists to offset the hue of the mapped image individually across red, yellow, green, cyan, blue, and magenta.

About the Dolby Vision™ Trims Toggles

• Apply: Enable or disable the Creative Trims. Useful to validate content before and after Creative Trims.

  Warning: If Apply is disabled, exporting a Dolby Vision XML shows the default values and not the edited trims.

• Lock: Enable or disable any modification to Creative Trims. Use it when performing a playback for review to ensure that no unwanted modifications are applied. If you do not have a Dolby Vision license, Lock becomes enabled and non-editable so you can still view the Creative Trims from an imported Dolby Vision XML even if you cannot edit the trims.

• Reset: Use this control to reset the current Trims. Use Reset All to reset all trim as for CM 2.9/4.0 for all Mastering and Target displays.

  Note: Mid Tone Offset (exclusive to CMv4.0) is a parameter global to all Target Displays and is generated by the Dolby Analysis. To reset the Mid Tone Offset, you must perform a new analysis.

About Interpolating Creative Trims

It is possible to create Creative Trims for multiple Target Displays. By manually creating the Trims for the selected Target Display or start from the Creative Trims you have created for Target Displays using the Interpolation tool. To be able to interpolate Creative Trims, you need at least the 100-nits Target Display to be created. If the HDR FX contains Creative Trims for multiple Target Displays, they are used to interpolate Trims for the current Target Display, including animation. Use the following options:

• Current Shot: Only the Creative Trims of the current shot are interpolated for the current Target Display.
• Selected Shots: Creative Trims of selected shots are interpolated for the current Target Display.
• All Shots: Creative Trims of all shots are interpolated for the current Target Display.

Creative Trims Interpolation Limitations:

• If you create a target for a trim (for example, 100 nit SDR trim or a 1000 nit HDR trim) you cannot have two trims with the same luminance value.
• When creating a custom trim target, there must be at least one PQ 10-bit code value difference from all other targets in the trim.

If the current shot is Locked or shots are locked when using Selected Shots or All Shots, an error message is displayed since it is not possible to interpolate on locked content.

To Animate Trims

You can animate trims. For more information on animation in general, see Animating Keyframes.

To affect multiple segments at the same time:

1. In Timeline, select multiple HDR FX segments and apply the same modifications to the selection. This can be very helpful when modifying similar looking content of when modifying Mid Tone Offset.

About Render Options

When using eCMU, the Rendering capabilities are not available since the FX does not produce any media. The Rendering options are gray out. When using iCMU, it is possible to enable the Cache iCMU Intermediates option (located in Setup menu) and in this case, rendering can be done (that is, local, Background Reactor, and Burn).