Documentation on tvall

Task: tvall
Purpose: Interact with a previously displayed image
Categories: visual display

        TVALL is a WERONG/MIRIAD task which allows interactive
        modification of the TV lookup tables, etc. Usually this would be
        used to manipulate an image previously loaded with TVDISP.
        A menu for operations
        to be performed will appear on the TV screen. The following are
        possible: 

        Choose the channel being displayed (Select the channel number
        from the menu). 

        Blink between two channels (The mouse y-coordinate determines
        the blink rate. It blinks between the current and succeeding
        image, mod 3. Hit any button to stop blinking). 

        Fiddle the lookup tables (The transfer function is governed by
        the mouse position. Hit any button to finish the command). 

        Change the lookup tables between black and white, or colour. 

        Zoom and pan (the left button zooms in, the middle button zooms
        out, and the mouse position controls pan. The cursor drawn on
        the IVAS gives the position, on the unzoomed screen, of the
        central pixel currently being displayed. To finish, hit the
        right button.). 

        Switch the menu off (by `selecting' the asterisk). This is
        useful if you want to take a photograph of the screen. 

        Return cursor position. The coordinates given are coordinates
        (not image coordinates). 

Key: server
        The TV device. No default. See the Users Manual for information
        on how to specify this.