fb-png — save a framebuffer image in a color Portable Network Graphics (PNG) file
fb-png [-ic ] [-# nbytes/pixel] [-g gamma] [-F framebuffer] [-s squaresize] [-w width] [-n height] [file.png]
fb-png
will take a region of a framebuffer display and save it as a color
png
format file.
The environment
variable
FB_FILE
is used to select the display device (see
brlcad(1)).
If this variable is not set, the default device for your system will
be used.
Alternatively, the framebuffer may be explicitly specified
by using the
-F
flag.
By default, the output
png
file, and the requested framebuffer size, is assumed to be 512x512 pixels.
The
-s
flag will set both the file height and width to be the given size, while
-w
and
-n
are used for setting them individually.
A first quadrant coordinate system is used (origin in lower left of
screen), and the area saved is normally from this origin.
The
-i
flag switches to a fourth quadrant system, both in the storage order as
well as the origin offset coordinates (i.e. origin is now the upper left
corner of the screen).
The
-# nbytes/pixel
flag specifies the number of bytes per pixel. The only values accepted
are 1 and 3.
The
-c
flag specifies that the color map in the frame buffer should
be applied to the pixel values (crunched) before they are written to the
output file.
The
-g gamma
flag sets the specified gamma correction value into the created PNG
file. A value of 0.6 is a close approximation of PC display monitors.
A negative gamma value disables writing a gAMA chunk out entirely (and
is the default).