This attribute indicates the method to be used when finding the output value of a LutMap for an input value part way between two table entries. If it is set to 0 (the default) then linear interpolation is used. Otherwise, nearest neighbour interpolation is used.

Using nearest neighbour interpolation causes AST__BAD to be returned for any point which falls outside the bounds of the table. Linear interpolation results in an extrapolated value being returned based on the two end entries in the table.

Note, the value of this attribute may changed only if the LutMap has no more than one reference. That is, an error is reported if the LutMap has been cloned, either by including it within another object such as a CmpMap or FrameSet or by calling the AST_CLONE function.

LutMap