Creative Effects > Keyer > Refining the Key >
Suppressing Colour Spill

After you create a key and key out any trouble areas, some of the background colour may have spilled over at the edge of the key. In the Keyer, you can use the colour suppression tools to suppress or disguise colour spill in the front clip. You can:

- Use Spill controls in the Keyer or Colour menu to suppress a selected colour and shift colours adjacent to the selected colour.
- Adjust the Suppression curve in the Colour menu to suppress a selected colour.
- Adjust the Hue Shift curve in the Colour menu to perform a hue shift on a selected colour.

Adjusting Spill Controls

Use the Spill controls in the Keyer or Colour menu to eliminate and disguise the colour spill in any key you create except a luminance key. You can sample the colour you want to remove, and then adjust the Range and Hue fields to suppress the selected colour and shift its adjacent colours.

(a) Spill Colour pot(b) Auto CC button in Range menu(c) Spill fields

When you sample an image to generate a key from a Range menu, the sampled colour in the Spill colour pot is also updated. However, the inverse is not true—if you sample a colour using the Spill colour pot, sampled colours used to generate keys are not updated. You can therefore sample colour spill without affecting the original sample.

NoteTo apply these settings to the key, the Auto CC button must be enabled.

To remove colour spill from a key:

1. Click Result so that you can see changes as you make them.
2. In the Keyer, do one of the following:
   - Click Keyer to show the Keyermenu.
   - Click Colour to show the Colour menu.
3. Enable Auto CC to apply the Spill settings to the front clip.
4. The Spill colour pot displays the colour that will be suppressed in the clip. By default, the original colour extracted from the key-in clip is displayed. In many cases, you can use this colour because the colour spill is the same colour as the original colour. However, if the colour spill is not the same, change the colour sample. Click the colour pot, use the colour picker to sample the colour spill in the image window, and then click the colour pot again.
   NoteWhen you select the colour you want to key from a Keyer menu, the colour that appears in the Spill colour pot is automatically updated to match the key colour. However, the inverse is not true—when you sample a colour from the Spill colour pot, the sampled colour used to generate a key is not updated.
5. Drag in the Spill fields to remove the colour spill.

   Drag: | To:
   --- | ---
   Range | Suppress the primary sample colour where there is colour spill (along the edges of the key).
   Hue | Modify colours that are adjacent to the primary sample and further remove colour spill.

   NoteYou can reset the Spill parameters, Blend parameters, and the Edge Balance trackball by clicking Reset, located left of the Edge Balance trackball.

Adjusting the Suppression Curve

If the edge of your key is relatively small, you can eliminate colour spill by suppressing it from the Colour menu. Sample the colour you want to suppress and then suppress that colour where necessary.

To apply settings from the Colour menu to the key, the Curves button must be enabled in the Colour or Keyer menu. The Curves button is enabled by default.

(a) Curves button in Colour menu

To suppress colour spill:

1. Click Result so that you can see the changes as you make them.
2. Click Colour.

   The Colour menu appears.

   (a) Colour curves(b) Plot button(c) Edit Mode box

   The Colour menu displays colour curves over a hue spectrum. When you modify the shape of a curve over a region of the spectrum, only those colours are affected.

3. Enable Curves to apply the colour curves of the hue spectrum to the front clip.
   NoteWhen the Curves button is disabled, settings in the Colour menu are bypassed.
4. Click Supp to modify the Suppression curve.
5. The colour pot next to the Suppress button displays the colour that will be suppressed in the clip when you modify the curve. By default, the original colour extracted from the key-in clip is displayed. In many cases, you can use this colour because the colour spill is the same colour as the original colour. However, if the colour spill is not the same, change the colour sample. Click the colour pot, use the colour picker to sample the colour spill in the image window, and then click the colour pot again.

   (a) Suppressed colour curve

6. Click Plot.

   The cursor turns into a colour picker.

7. Select a pixel within the spill.

   A red vertical bar appears in the hue spectrum identifying the colour to be suppressed.

8. Select Move from the Edit Mode box so you can use the cursor to move the points along the Suppression curve.
9. On the Suppression curve, drag the point closest to the plotted colour down to a value of 25, intersecting the plotted colour.

   The colour spill is suppressed.

10. Continue modifying the shape of the curve until you are satisfied with the result.
11. Click Saturation to adjust the saturation of the spill.
    NoteOnce you remove the saturation from a spill, you may want to increase the values for the other curves (for example, red and green if you removed a blue spill) to reconstruct some of the natural colours at the edge of the keyed image.
12. Click Red, Green, or Blue to edit individual colour curves.
13. Click Luminance to adjust the luminance of the spill.
    NoteTo apply changes made in the Colour menu, make sure the Adjust button is enabled.

Adjusting the Hue Shift Curve

You can disguise colour spill by shifting its hue so the colour blends better with the background. Sample the colour to which you want to shift the colour spill and then adjust the Hue Shift curve to shift the colour spill accordingly.

To apply settings from the Colour menu to the key, the Curves button in the Keyer or Colour menu must be enabled. The Curves button is enabled by default.

(a) Curves button in Colour menu

To create a hue shift:

1. Click Result so that you can see the changes as you make them.
2. In the Keyer, click Colour.

   The Colour menu appears.

   (a) Hue spectrum(b) Colour curves(c) Plot button(d) Edit Mode box

   The Colour menu displays colour curves over a hue spectrum. When you modify the shape of a curve over a region of the spectrum, only those colours are affected.

3. Enable Curves to apply the colour curves of the hue spectrum to the front clip.
   NoteWhen the Curves button is disabled, settings in the Colour menu are bypassed.
4. Enable Hue to modify the Hue Shift curve.
5. Click the colour pot next to the Hue button.

   The colour picker appears.

6. Select or pick a colour.
7. Click again inside the colour pot next to the Hue button to set the Hue colour.
8. Click Plot.
9. Select a pixel within the spill.

   A red vertical bar appears in the hue spectrum identifying the colour to be shifted.

10. Select Move from the Edit Mode box so you can use the cursor to move the points along the Suppression curve.
11. On the Hue Shift curve, drag the point closest to the plotted colour down to a value of 75, intersecting the plotted colour.

    The colour spill is shifted toward the Hue colour.

12. Continue modifying the shape of the curve until you are satisfied with the result.

    (a) Hue Shift colour(b) The colour values in the image that fall in this range (under the curve) are shifted to the Hue Shift colour