Query of the displayable greyvalues.
query_grey returns all greyvalues that are used for greyvalue output (disp_image) and that can be reproduced exactly in the active window. They can be set with the set_grey call. The number of displayable greyvalues can be set with set_system(::'num_grey_*',...:) before opening the first window.
Greyval (output_control) |
integer-array -> integer |
tuple of all displayable greyvalues. |
query_grey returns TRUE, if a window is active. Otherwise an exception is raised.