When I scan a old book that is turned yellow, I remove the yellow by using Photoshop like this.
Adjustment -> Hue/Saturation
Yellowsand set Lightness to 100
Redsand set Lightness to 100
By this operation I can remove the unnecessary color clearly. (Gray scale does not work like this.)
But not everybody have a Photoshop and I think ImageMagick can do same thing. So I tried to find the options for that operation in ImageMagick, but I could not find it.
How can I remove yellow color from a aged book?