pdl> $x = sequence 2,2,3 # "2x2 planar RGB" image, 4 unique colors pdl> $x = $x-> glue( 0, $x ) # "4x2 RGB" image, 4 unique colors pdl> $x = $x-> glue( 1, $x ) # "4x4 RGB" image, still 4 unique colors pdl> $x-> set( 2,2,2, 100 ) # make them 5 pdl> p$x [ [ [0 1 0 1] [2 3 2 3] [0 1 0 1] [2 3 2 3] ] [ [4 5 4 5] [6 7 6 7] [4 5 4 5] [6 7 6 7] ] [ [ 8 9 8 9] [ 10 11 10 11] [ 8 9 100 9] [ 10 11 10 11] ] ] pdl> p $x-> clump(2)-> transpose-> uniqvec-> getdim( 1 ) 5