Colour Grading: RGB and Hue Curves > Modifying Red, Green, and Blue Channels > Modifying Hue, Saturation, Luminance, and Lightness >

# Saturating and Suppressing Colours

You can adjust the purity of colours in the image by modifying the saturation. You can suppress or saturate colours in a range or across the entire image.

To saturate and suppress colours in the image:

1. Indicate the colour grading stage at which the curve modification is being applied:
   - To work on the initial primary grade, click Input.
   - To make curve modifications for secondary colour grading, enable a secondary layer.
2. Click Hue and then click Sat to display the Saturation curve.

   The Saturation curve is plotted to the hue spectrum.

3. Sample the colours you want to use as a reference for your adjustments. See Plotting Colour Values when Adjusting Curves.

   A vertical line representing the reference colour is plotted on the Saturation curve.

4. To select a vertex, click it. To select several vertices, draw a selection box around them.
5. Saturate or suppress the colour:
   - To saturate the colour displayed in the hue spectrum, drag selected vertices up.
   - To suppress the colour displayed in the hue spectrum, drag selected vertices down.
   Tip You can also select a vertex to use tangent handles to adjust the curve.
6. To move several selected vertices, select them and then drag one. To restrict vertex movement to the Y axis, press Shift while moving the mouse. To restrict vertex movement to the X axis, press Shift+Alt.
   TipTo create a greyscale image, select all the vertices and then drag them all the way down. You can then drag vertices up to saturate isolated ranges of colour.
7. To add a vertex to the curve, place the mouse cursor over the area on the curve where you want to add the vertex and then press A. To lock the curve in place while adding a vertex, press Shift+A on the curve.
8. To delete vertices, select them and then press D.
9. Edit the curve until you are satisfied with the results.