FB-PNG(1)

NAME

fb-png - save a framebuffer image as a Portable Network Graphics (PNG) file

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SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
SEE ALSO
AUTHOR
COPYRIGHT
BUG REPORTS

SYNOPSIS

fb-png [-i] [-c] [-# _nbytes/pixel_] [-F _framebuffer_] [-g _gamma_] [-s _squaresize_] [-w _width_] [-n _height_] [file.png]

DESCRIPTION

fb-png reads a region of a framebuffer and saves it as a PNG (Portable Network Graphics) file. If no output file name is given, the data is written to standard output.

By default the region read is 512x512 pixels in first-quadrant order (origin at the lower left); use -s, -w, and -n to change the size. If the open framebuffer is smaller than the requested size, the region is trimmed to fit. Use png-fb(1) to display a PNG file in a framebuffer.

OPTIONS

-i: Read the framebuffer bottom-to-top, inverting the image vertically (fourth-quadrant order, origin at the upper left).
-c: Apply ("crunch") the framebuffer color map to pixel values before writing. Ignored if the framebuffer has no map or a linear one.
-# nbytes/pixel: Number of bytes per pixel: 1 for grayscale or 3 for color (the default).
-F framebuffer: Specify the framebuffer device. Defaults to the FB_FILE environment variable (see brlcad(1)).
-g gamma: Write the specified gamma correction value into the PNG gAMA chunk. A value of 0.6 approximates PC display monitors. A non-positive value (the default is -1.0) disables writing the gAMA chunk entirely.
-s squaresize: Set both width and height to squaresize pixels (default 512).
-w width: Set the width in pixels (default 512).
-n height: Set the height in pixels (default 512).
-h, -?: Print a usage message and exit.

EXAMPLES

Example 1. Render a model and capture the framebuffer to PNG

rt -s 1024 -F /dev/X moss.g all.g &
fb-png -F /dev/X -s 1024 moss.png

Ray traces the moss.g model into a 1024x1024 X11 framebuffer with rt(1), then grabs that framebuffer and saves it as a PNG image of the same size. Matching the -s size to the framebuffer ensures the whole image is captured.

Example 2. Save the lower-left quadrant of the default framebuffer

fb-png -w 256 -n 256 crop.png

Reads only a 256x256 region (anchored at the origin) from the framebuffer named by the FB_FILE environment variable and writes it to crop.png.