The interactive system makes use of interactive graphic display and cursor or keyboard input to provide fast and friendly image processing capabilities. The system must be activated with the command ILOAD which copies the image to be processed into dynamic memory and opens the display device if necessary. Processing is performed on the copy, not on the original file, and a buffer is kept which allows the user to go back one stage of processing with the command IUNDO. Default mode for entry of positions etc. is via interactive cursor. Keyboard entry can be selected as an option when the system is started and can be changed by the command IMODE. As well as facilities for manipulating and displaying the 2D image data, there are commands which derive 1D data, such as radial profiles. At any point in processing the 2D and 1D data may be saved to file with the commands ISAVE and ISAVE1D and may then be processed by other ASTERIX commands. The original image file may be processed by other ASTERIX commands whilst the interactive system is active. A new image may be loaded at any time with the same command, ILOAD and a different display device (eg hardcopy) can be opened with DOPEN without losing the image. To release the image use the command ICLOSE. The results of processing will be lost at this point unless they have been saved explicitly.
The exact format of both 2D and 1D plots can be controlled using GSET. All plotting attributes thus set are saved with the data by ISAVE and ISAVE1D, such that the general plotting command GDRAW will reproduce identical plots.