dpy
Specifies the display screen on which the Xv Server is to accept requests from Xv clients. If the display option is not specified, Xv uses the display screen specified by your DISPLAY environment variable. The display option has the format hostname:number. Using two colons (::) instead of one (:) indicates that DECnet is to be used for transport.
port
Defines the port to which the still is output'd.
d
Defines the drawable from which the still is to be captured. Pixmaps are currently not supported.
gc
Defines the graphical context. GC components are: subwindow-mode, clip-x-origin, clip-y-origin, and clip-mask.
vx,vy,vw,vh
Define the location and size of the destination video region into which the still is to be written. vx and vy define the x and y coordinates of the upper-left corner of the video region; vw and vh define the width and height, in pixels, of the video region.
dx,dy,dw,dh
Define the location and size of the source drawable from which the still image is to be captured. dx and dy define the x and y coordinates of the upper-left corner of the drawable region; dw and dh define the width and height, in pixels, of the drawable region.