Andrea Zangrando a écrit : > ... and I wish to change the gradation of colors > from blue to red, how could i do? Hello, here's how I build such a palette. a = 15; palwhiteblue = rgb(a:0, a:0, a, max=a); palredwhite = rgb(a, 0:a, 0:a, max=a); palwhite = rep(rgb(1,1,1), 8); palRWB = c(palredwhite, palwhite, palwhiteblue); of course, to adapt to your own uses. hih Vincent