`setup seawifs colorscale'
{
    # Formula to convert chlorophyll (C) to 'image' value (V):
    #     V = [2 + log(C)] / 3.699
    # transformation, C values ranging from 0.01 to 64 map, 
    # logarithmically, into the V range 0 to 1.

    set image range 0 1
    open "gawk '{print($1/255,$2/255,$3/255)}' seawifs.palette |"
    read image colorscale rgb
    close
}

# Vertical palette
`palette label .value'
{
    # Tics
    .x0. = .px0.
    .y0. = {rpn \.word2. log 2 + 3.699 / .py1. .py0. - * .py0. +} 
    .x1. = {rpn .px0. "M" ascent 0.5 * -}
    .y1. = {rpn \.word2. log 2 + 3.699 / .py1. .py0. - * .py0. +}
    draw line from .x0. .y0. to .x1. .y1. cm

    # Numbers
    draw label  "\.word2." centered at \
	{rpn .x0. "M" width 2 * -} \
	{rpn .y0. "M" ascent 2 / -} cm
}

`draw seawifs palette .x_ll_cm. .y_ll_cm. .x_ur_cm. .y_ur.cm.'
{
    set font size 0
    set tic size 0
    .px0. = \.word3.
    .py0. = \.word4.
    .px1. = \.word5.
    .py1. = \.word6.

    draw image palette axisright box .px0. .py0. .px1. .py1.
    set font size 5
    palette label ".01"
    palette label ".02"
    palette label ".03"
    palette label  ".02"
    palette label  ".03"
    palette label  ".05"
    palette label  ".1"
    palette label  ".2"
    palette label  ".3"
    palette label  ".5"
    palette label  "1"
    palette label  "2"
    palette label  "3"
    palette label  "5"
    palette label "10"
    palette label "15"
    palette label "20"
    palette label "30"
    palette label "50"

    set font size 8
    draw label "Chlorophyll a Concentration, mg/m$^3$" centered at \
	{rpn .px0. .px1. + 2 /} {rpn .py0. "M" ascent 5 * -} cm
    set tic size 0.1
}

    .
    .
    .

draw seawifs palette 20 4 20.3 8

    .
    .
    .