Using Workbench Command

OFFSCREEN RENDERING OF SCENE TO AN IMAGE FILE
   wb_command -show-scene
      <scene-file> - scene file
      <scene-name-or-number> - name or number (starting at one) of the scene in
         the scene file
      <image-file-name> - output image file name
      <image-width> - width of output image(s), in pixels
      <image-height> - height of output image(s), in pixels

      [-use-window-size] - Override image size with window size

      [-no-scene-colors] - Do not use background and foreground colors in scene

      [-set-map-yoke] - Override selected map index for a map yoking group.
         <Map Yoking Roman Numeral> - Roman numeral identifying the map yoking
            group (I, II, III, IV, V, VI, VII, VIII, IX, X)
         <Map Index> - Map index for yoking group.  Indices start at 1 (one)

      [-conn-db-login] - Login for scenes with files in Connectome Database
         <Username> - Connectome DB Username
         <Password> - Connectome DB Password

      Render content of browser windows displayed in a scene into image
      file(s).  The image file name should be similar to "capture.png".  If
      there is only one image to render, the image name will not change.  If
      there is more than one image to render, an index will be inserted into
      the image name: "capture_01.png", "capture_02.png" etc.

      If the scene references files in the Connectome Database,
      the "-conn-db-login" option is available for providing the 
      username and password.  If this options is not specified, 
      the username and password stored in the user's preferences
      is used.

      The image format is determined by the image file extension.
      The available image formats may vary by operating system.
      Image formats available on this system are:
          bmp
          jpeg
          jpg
          png
          ppm
          tif
          tiff

      The result of using the "-use-window-size" option
      is dependent upon the version used to create the scene.
          * Versions 1.2 and newer contain the width and 
            height of the graphics region.  The output image  
            will be the width and height from the scene and
            the image width and height specified on the command
            line is ignored.
          * If the scene does not contain the width and height
            of the graphics region, the width and height specified
            on the command line is used for the size of the 
            output image.