MOVIE-Browse through slices of a cube.

Usage:

movie in axis low=? high=?

Description:

This routine takes a three-dimensional NDF and displays its two-dimensional slices sequentially on a grey or colour graphics device.

Parameters:

DIALOG

DIALOG = _CHAR (Read) The dialogue mode. If false ('F' or 'N') all frames of the cube will be displayed once in forward order. If true ('T' or 'Y') the routine will not display anything initially, but repeatedly ask for a menu option via the MENU parameter. 'G' for graphic is also permitted, but has the same meaning as 'T'. ['F']

INFO

INFO = _LOGICAL (Read) If true, informational messages are given. Such as, which frame is currently displayed. [YES]

MODE

MODE = _CHAR (Read) 'Fast', 'Fill', or 'Square' for (i) a tiny but quick display, (ii) to use the whole display area available, (iii) the biggest display with square pixels that is possible in the area available. The mode can be abbreviated to two characters and is case-insensitive. ['Fast']

IN

IN = NDF (Read) The input NDF. It must be three-dimensional - not counting degenerate axes.

DEVICE

DEVICE = GRAPHICS (Read) The graphics display device. It must be a screen device, not a printer device.

AXIS

AXIS = _INTEGER (Read) The number of the movie axis. Of the three axes in the input cube this is the one not visible in the display. This is the axis to count the frames of the movie. [3]

LOW

LOW = _REAL (Read) The minimum data value from the cube to be displayed. Values less than this are displayed in the same colour.

HIGH

HIGH = _REAL (Read) The maximum data value from the cube to be displayed. Values greater than this are displayed in the same colour.

MENU

MENU = _CHAR (Read) The application will ask repeatedly for the menu option, until 'Q' is chosen. These options are also available from the keyboard if dialogue is graphic. ['F'] - F: Display each frame in forward order. - B: Display each frame in backward order. - I: Ask for FRAME parameter and display specified frame. - P: Display previous frame. - N: Display next frame. - Q: Quit. - ?: Help.

FRAME

FRAME = _INTEGER (Read) The frame number to be displayed next. Note that frames are counted in NDF pixel indices, i.e. from the NDF's lower bound to its upper bound.

Source comments:

   The colour table of the display is unaltered so that a previously
   loaded colour table will be used. Bad values will be displayed in
   the display background colour, which in general is distinct from
   the colour for the lowest (or highest) data value.

   This routine is quite primitive. It does not use axis data or
   spectroscopic values from the Specdre Extension. Pixels and slices
   in the cube are addressed by their NDF pixel indices, which are
   integer numbers, usually starting at 1.

   The routine also does not pay much attention to the precise timing
   of the display. The following list gives activities that the routine
   spends time on and how the user can exert some control over the
   timing.

   -  Before a frame can be displayed it must be extracted from the
      cube. The time taken for this depends greatly on whether the
      frame counting axis is the first or last axis. Taking slices is
      fastest if AXIS=3 and can be very slow if AXIS=1, so it may be
      useful to re-arrange the axes of a cube that will be viewed
      often with the same frame-counting axis. Another way to reduce
      the time for taking slices from the cube is to use as small a
      cube as possible: If it is a-priori known that only a certain
      range of frames will be looked at, or that only a certain part
      of all frames is interesting, then the input cube can be given
      as an appropriate subset of the actual disk file.

   -  Also before a frame can be displayed it must be converted
      according to the colour capabilities of the display.

   -  Each frame needs to be extracted and converted only once and
      can be viewed several times, converted frames are kept in a
      workspace until the routine exits.

   -  In the sequence displays each frame is converted and displayed
      before the routine goes on to the next frame.

   -  When a specific frame is requested it is extracted, converted
      and displayed (unless it has been viewed before).

   -  When the next or previous frame relative to the displayed one
      is requested, it is extracted and converted if necessary. Then
      it is displayed. In anticipation of another request of the same
      type the next or previous frame is extracted and converted
      immediately.

   -  Even if a frame has been converted before, it takes some time
      to re-sample it from cube pixels to display pixels. This time
      can be minimised by choosing the fast mode, where a cube pixel
      is only one display pixel.

   -  Disruptions occur in the display of a sequence of frames due to
      the unpredictable need for the machine to page memory.

   -  Display may be over a network and bandwidth has to be shared
      with other users. This too causes disruptions of frame
      sequences.

   In summary, it may be best to

   -  put on your spectacles and settle for the fast (and tiny)
      display,
   -  decide which part of the cube is interesting and specify
      only that sub-cube as input,
   -  begin the forward sequence to convert the whole input sub-cube,
   -  have a cup of tea if AXIS=3 and the cube is not small,
   -  use the options 'I', 'P', 'N' to look at individual frames in
      your own time.

   It is not possible to write the cube as converted for display.
   Such a cube would be of limited use, since it might contain only
   part of the input cube and since its scaling depends on the colour
   capabilities of the display used.