Forum Moderators: not2easy
using FW or PS I would select the image and then alter 'Hue saturation' and 'colour levels'. Play with the command until the red and blue have been removed.(RGB mode)
Alternantivley (in FW) you could convert the image to grey scale
Then draw a green rectangle over the image on a new layer - select the layer opacity in the layer pallette and drop to desired level.
then alter the contrast and brightness to maintain a tonal match with original image.