To Set Up a Chroma Key

Set up the chroma key with the source you want to use and adjust the parameters. Ensure that the chroma key output has been selected on a keyer so that you can view the output as you adjust the parameters.

  1. Click Navigation Menu > Live Assist > Chroma Key.
  2. Click CK X for the chroma key engine you want to use.
  3. Click CK Source and select the video source you want to use for the chroma key.
    Note: You can only select a physical input, Media-Store, or MediaWipe for a chroma key. You can also select an Aux Bus, but the source selected on the Aux Bus must be valid for the chroma key.
  4. Click the Color button for the color of the background you are using for your chroma key.
  5. Click Init.

    The chroma key engine initializes and attempts to remove the selected background color from the video. Any further adjust is only required if you want to adjust aspects of the key.

  6. Click the Key Type button for the chroma key mode you want to use.
    • HR Wedge Key — Based on the standard chroma keyer and discriminates between the color vector angle and level of the background color vs the color vectors and levels in the foreground components.
    • HR Detail Key — Differs from the standard chroma keyer in that it adds luminance dependency to a three-dimensional spherical color discriminator.
    • HR Combination Key — Combine the two modes to offer good capture of high luma detail in the edge regions as well as compensation for similar foreground and background levels.
    Note: All adjustments are always available, even if the are not applied by the selected mode.
  7. Adjust the Wedge Key Parameters as follows:
    • Gain — use this setting to set the Angle Control to 100 and the Lift to 0 and then adjust this setting until the background is fully removed, leaving a reasonable edge to the key. Too much gain will produce hard and undesirable edges.
      Tip: Adjust the Gain with the Bkgd Luma Suppress to balance between background removal and edge quality.
    • Bkgd Luma Suppress — use this setting to compensate for uneven color or lighting in the shot to ensure the chroma background is fully suppressed.
      Tip: Turn on a box mask in the keyer you are using to view the chroma key output to compare the backgrounds. The masked area shows the background source without the key settings applied.
    • Angle — use this setting to change the color wedge angle (wedge shape) that is used to detect areas of foreground (fill) and background (alpha) based on the chosen color vector. This can help fill in areas of heavy spill without hardening edge detail.
    • Lift — use this setting to amplify the generated alpha signal to fill in areas of transparency.
    • Highlight Correction — use this setting to lift areas of the image might contain high luminance levels at edge boundaries. This could be due to lighting conditions, camera setup, or subject.
  8. Adjust the Detail Key Parameters as follows:
    • Clip — use this setting to clip between the foreground and background. You are looking to achieve complete background removal.
      Tip: Clip should be set to the point where the background is just removed. Setting it too high will reduce edge quality.
    • Gain — use this setting to lift the fill image. You are looking to achieve solid fill content.
      Tip: Setting the gain too high may introduce dark boundaries.
    • Shadow Sensitivity — use this setting to adjust the level of dark image areas, particularly in cast shadow areas.
    • Shadow Density — use this setting to adjust the apparent lightness of the dark / shadow areas in conjunction with the Shadow Sensitivity.
    • Highlight Sensitivity — use this setting to fill areas with specular highlights, such as reflective surfaces, that can show through to the background.
  9. Adjust the Global Parameters as follows:
    • Chroma Angle — use this setting to select the fill color that has been detected as color spill. You should not have to adjust this setting.
    • Re-Spill — use the Re-Spill Color and Re-Spill Sat settings to select a color that is near the average color of the background/lighting that needs to be added into those areas of the fill that contain the spill from the chroma set.
  10. Adjust the Miscellaneous Parameters as follows:
    • Edge Softness — use this setting to filter the edges to eliminate undesirable hard edges and add realism to a scene by simulating depth of field characteristics.
    • Bkgd Norm Adjust — use this setting to offset the detected level of the chroma background and allow for fine tuning.
      Tip: If the subject image contains fine detail such as fine hair with a luminance level that is close in value to the chroma set color background level – it may be difficult to provide good separation between background and foreground elements.