Creative Effects > Colour Warper > Correcting Colour Imbalances >
Setting Black and White Levels

When you balance the colours in a clip, you should always start with the darkest and lightest parts of the image. You may, for example, need to establish parameters for the black and white (luma) content to ensure that the intensity of the image is in accordance with established broadcast parameters. These parameters are known as black points and white points. You use the Black and White fields to establish black and white points.

(a) Black field(b) White field

Black field
  Modifies the luma in the image's shadows without affecting the chroma.
White field
  Modifies the luma in the image's highlights without affecting the chroma.

To set black and white levels:

1. Sample the highlights in the image. To determine the white point, select a white that appears to be flat rather than reflective so that you obtain a more accurate reading. Do not use a highly reflective surface such as a window or metal surface as they are often too bright. Enable Plot and then sample the whites in the result clip.

   In the Basics menu, a red plot line is displayed in the 2D luma histogram indicating the luma value of the sampled whites in the result clip.

2. While viewing the 2D luma histogram and the image, adjust the white level to modify the luma value and set the white point—drag left to darken the highlights and right to lighten them. The Plot sample is updated as you drag the field.
   TipYou can view both the 2D luma histogram and 2D vectorscope to determine what adjustments you need to make to the highlights. For example, if the white point is set to an acceptable level in the 2D luma histogram but the sampled chroma value shows an unwanted colour cast in the 2D vectorscope, use the Highlights trackball to modify the chroma value in the highlights. See Removing Unwanted Colour.
3. Enable Plot and sample the shadows in the result clip to determine the black level. Sample the darkest part of the image to determine the black point.

   A red plot line is displayed in the 2D luma histogram indicating the luma value of the sampled blacks in the result clip.

4. While viewing the 2D luma histogram and the image, adjust the black level to modify the luma value—drag left to darken the shadows and right to lighten them. The Plot sample is updated as you drag the field.
   TipOnce the black level is set, you can use the Shadows trackball to adjust the chroma values in the highlights while viewing the plot sample in the 2D vectorscope. See Removing Unwanted Colour.