The Color > Color Eraser effect
Let's assume that we want to delete the green and blue colors in our image. This is easily done using the Color Eraser effect.
By erasing the color we understand erasing the data relative to the color composing the pixels and not modifying the opacity of the pixels. In other words, we unsaturate the pixels with a precise hue.
Original imageImage with green and blue hues erased
Start by selecting a color in the green area of the image in the Color box of the panel above. Part of the green pixels will then be unsaturated and turn to gray. To obtain a better finish, you may increase or decrease the tolerance or softness thresholds.
To select the pixels according to their hues, the color bar of the panel as well as the 4 mini-sliders will help you.
Progressively unsaturated hues
Completely unsaturated hues
The Invert button is used to invert the final result: saturated pixels become unsaturated and vice-versa. If necessary, the popup menu Display enables recovery of source image viewing.