5.10. Desaturate

5.10. Desaturate
	5. Color Tools

By using the Desaturate command, you can convert all of the colors on the active layer to corresponding shades of gray. This differs from converting the image to grayscale in two respects. First, it only operates on the active layer and second, the colors on the layer are still RGB values with three components. This means that you can paint on the layer, or individual parts of it, using color at a later time.

	Note
	This command only works on layers of RGB images. If the image is in Grayscale or Indexed mode, it can do nothing.

5.10.1. Activating the Command

You can get to this tools in several ways:

In the image menu through Tools → Color Tools → Desaturate… or Colors → Desaturate…,
by clicking on the tool icon in Toolbox, if this tool has been installed there.For this, please refer to Section 1.7, “Toolbox”.

5.10.2. Options

Figure 14.176. The “Desaturate” option dialog

Three options are available:

Choose shade of gray based on

Lightness: The graylevel will be calculated as

Lightness = ½ × (max(R,G,B) + min(R,G,B))
Luminosity: The graylevel will be calculated as

Luminosity = 0.21 × R + 0.72 × G + 0.07 × B
Average: The graylevel will be calculated as

Average Brightness = (R + G + B) ÷ 3

Figure 14.177. Comparing the three options

Original image

“Lightness” applied

“Luminosity” applied.

“Average” applied.