= Gimp =

== Remove color ==
 * pick color with with the Color Picker ( key o)
 * select fuzzy select (key u ) set threshold as 0 
 * click on the color to select
 * press ctrl+x to remove 

== Replace color in image ==
 * select original color with the Color Picker ( key o)
 * select menu Colors, Map, Color Exchange
 * Paste the RGB code HTML notation in the from color
 * Write the target color RGB code HTML notation in the to color
 * click OK