def convert_to_rgb(minimum, maximum, value):
    minimum, maximum = float(minimum), float(maximum)
    halfmax = (minimum + maximum) / 2
    if minimum <= value <= halfmax:
        r = 0
        g = int( 255./(halfmax - minimum) * (value - minimum))
        b = int( 255. + -255./(halfmax - minimum)  * (value - minimum))
        return (r,g,b)
    elif halfmax < value <= maximum:
        r = int( 255./(maximum - halfmax) * (value - halfmax))
        g = int( 255. + -255./(maximum - halfmax)  * (value - halfmax))
        b = 0
        return (r,g,b)

def rgb(minimum, maximum, value):
    minimum, maximum = float(minimum), float(maximum)
    ratio = 2 * (value-minimum) / (maximum - minimum)
    b = int(max(0, 255*(1 - ratio)))
    r = int(max(0, 255*(ratio - 1)))
    g = 255 - b - r
    return r, g, b

import sys
EPSILON = sys.float_info.epsilon  # smallest possible difference

def convert_to_rgb(minval, maxval, val, colors):
    fi = float(val-minval) / float(maxval-minval) * (len(colors)-1)
    i = int(fi)
    f = fi - i
    if f < EPSILON:
        return colors[i]
    else:
        (r1, g1, b1), (r2, g2, b2) = colors[i], colors[i+1]
        return int(r1 + f*(r2-r1)), int(g1 + f*(g2-g1)), int(b1 + f*(b2-b1))

if __name__ == '__main__':
    minval, maxval = 1, 3
    steps = 10
    delta = float(maxval-minval) / steps
    colors = [(0, 0, 255), (0, 255, 0), (255, 0, 0)]  # [BLUE, GREEN, RED]
    print('  Val       R    B    G')
    for i in range(steps+1):
        val = minval + i*delta
        r, g, b = convert_to_rgb(minval, maxval, val, colors)
        print('{:.3f} -> ({:3d}, {:3d}, {:3d})'.format(val, r, g, b))

r = [red_curve_1, red_curve_2][value>=halfmax]
g = [green_curve_1, green_curve_2][value>=halfmax]
b = [blue_curve_1, blue_curve_2][value>=halfmax]

colorsys.hsv_to_rgb(value, 1, 1)