MACROMEDIA FREEHAND 10-USING FREEHAND Use Manual page 459

You can also use the Find & Replace Graphics feature to automatically
recalculate blends for different printer resolutions.
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For spot-to-spot blends and spot-to-spot gradient fills, set appropriate halftone
angles for each spot color in the blend or gradient fill in the Separations panel
in the Print Setup dialog box. Undesirable moiré patterns will result if you
overprint a spot color on top of another when the halftone angles are set
incorrectly.
For process colors, up to four inks describe the color at the each end of a
transition, and each ink has its own degree of banding. Calculate the tint band size
for the most visible ink—usually black or magenta. Narrower bands create
smoother transitions. A size of 0.05 points or less is required for high quality
output. For less exacting output, tint bands of 1 to 2 points may be acceptable.
Use these formulas to determine the optimum values to minimize banding when
printing color transitions.
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N= (P/R)
where N is the number of tints the output device can produce, measured as P for
the printer resolution (P) divided by R for the screen ruling, squared.
T= N * Z
where T is the actual number of tints available, measured as N for the printer's
number of tints available, multiplied by Z for the percentage difference between
colors expressed as a decimal value (for example, 5% = 0.05).
S= D/T
where S is the size of each tint band in a color transition, measured as D for the
distance between colors, divided by T, the number of tints available.
For process colors, up to four inks describe the color at each end of a transition,
and each ink has its own degree of banding. Calculate the tint band size (in points)
for the most visible ink —usually black or magenta. Narrower bands create
smoother transitions. A size of 0.05 points or less is required for high quality
output. For less exacting output, tint bands of 1 to 2 points may be acceptable.