CIGAL Reference Manual, Chapter 4 (Variables): iflags
usage: iflags = value
IFLAGS is an internally defined integer variable controlling options related to how image processor operations are executed. IFLAGS values provide a way to select hardware dependent options and their meanings will therefore vary for different image processing hardware. The value of the IFLAGS parameter can be changed at any time and remains set until it is explicitly modified again. The meanings of the IFLAGS settings are summarized below; levels can be combined by adding values.
Value 1 Switch "outmode" to 1 (default 0) for image reading and writing. Mode 0 is faster i/o but display tends to flicker, compared to mode 1. 2 Use direct memory access (no buffering) for image processor I/O.