IBM Release 1.93 manual Optimize Group, Variables, Guess

where level, R, G, and B are integers between 0 and 255, inclusive. The level column represents the signal level, and R, G, and B are the usual RGB colour components.

Choices of curve are linear, gamma, logarithmic, and MuLaw. The linear curve spaces the palette entries out evenly, with the maximum value in the picture being 255 and the minimum, 0. The gamma curve first takes the square root of the absolute value of the variable, restores the sign, and spaces out the result evenly. This accentuates details in the weaker-field regions, without losing definition in the higher-field regions. The logarithmic curve accentuates weak fields very strongly, which is very useful in some cases but tends to lose detail where the field is strong. The mathematical logarithm is modified to avoid floating-point runtime errors: it actually computes

where x has been normalized by the largest element in absolute value. The MuLaw curve uses the CCITT µ-255 codec curve, which is linear for values near the positive and negative limits, but puts the levels close together near zero. While this resembles a bipolar version of the logarithmic curve, it actually combines many of the advantages of the linear and logarithmic curves, since not all detail is lost at the highest values.

Syntax: SLICE file = <fname> xlo=<value> xhi=<value> , ylo=<value> yhi=<value> zlo=<value> zhi=<value> , phase=<value> variable = Ex

Example:

SLICE file = /var/tmp/v1aExIsourceZ.bmp xlo=0 xhi=xsize , ylo=0 yhi=ysize zlo=1.5*um zhi=1.5*um phase=0 , variable = Ex

3.1.10. OPTIMIZE Group

VARIABLES	Tell the optimizer which variables to optimize over. These must
	have been defined in a SET statement.
	Syntax: VARIABLES var1 ... varN
GUESS	Supplies a guess to the optimizer. A guess is a point in the N-
	dimensional parameter space. For an N-dimensional optimization
	run, N+1 guesses are required, each supplying all N variable values.
	The first guess is supplied by the SET statements where the
	optimization variables are defined, but additional ones can be
	supplied by GUESS statements. If more than N+1 guesses are

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