从163的blog搬运过来一个，试试。。。

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set box match
image 0133p560_ac51-w4-int-3.fits.gdf ! only used to set the limit
lim /rg


def image a1 0133p560_ac51-w4-int-3.fits.gdf write
def image a2 0133p560_ac51-w3-int-3.fits.gdf write
!def image a3 xxx.gdf write

def real rrr['a1%dim[1]','a1%dim[1]',3]
let rrr[,,1] a1
let rrr[,,2] a2
!let rrr[,,3] a3

clear
plot rrr /scal log 101 125 350 750 350 750
box p o out /abs /nob

把RGB仨图塞到一个三维数组里，然后plot这个三维数组就彩色了。。。