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PNG-FB(1)			    BRL-CAD			     PNG-FB(1)

       png-fb -	display	a Portable Network Graphics (PNG) image	file on	a

       png-fb [-Hicvz1]	[-gscreen_gamma] [-Fframebuffer] [-m#lines]
	      [-Ssquarescrsize]	[-Wscr_width] [-Nscr_height] [-xfile_xoff]
	      [-yfile_yoff] [-Xscr_xoff] [-Yscr_yoff] [file.png]

       png-fb reads a PNG format file from the named file, or from standard in
       if no file is specified,	and displays the image on the currently
       selected	framebuffer. The environment variable FB_FILE may be used to
       specify the current framebuffer,	see brlcad(1). Alternatively, the
       framebuffer may be explicitly specified by using	the -F flag.

       By default, the requested framebuffer size is assumed to	be 512x512

       The -g option specifies the gamma value for the screen where the	image
       is to be	displayed. Larger values will produce lighter colored display.

       If the -i flag is specified, the	image is inverted.

       The -c flag causes the screen to	be cleared before the image is
       displayed. The default behavior is to overwrite the current image with
       the new image without clearing the screen.

       The -v option will print	verbose	information about the PNG file.

       The -H option will print	a single line on standard output providing the
       dimensions of the image in a format readily usable in shell scripts,
       e.g. WIDTH=42 HEIGHT=17.

       The -z flag will	zoom and center	on the image being displayed to	make
       it fill the display area, using the libfb fb_zoom() routine. fb_zoom
       only offers integer zoom	factors, so displays with non-square screens
       (such as	the SGI	3D machines) may find this option of limited

       The -W scr_width	flag specifies the width of each scanline in the
       display device, in pixels.

       The -N scr_height flag specifies	the height in scanlines	of the display

       -S squarescrsize	set both the height and	width to the size given.

       -x file_xoff -y file_yoff and -X	scr_xoff -Y scr_yoff will offset into
       the file	or onto	the screen by the given	amounts. The coordinate	system
       for these offsets is first quadrant, with the origin at the lower left
       corner of the image.

       The -1 flag causes the image to be written to the framebuffer one line
       at a time, using	the fb_write(3)	routine. This is the default behavior.
       The -m #lines flag can be used to specify the number of lines to	be
       written to the framebuffer in rectangular blocks	of scanlines, using
       the fb_writerect(3) routine. In some circumstances, this	can result in
       significantly faster image display, at the expense of the image being
       written less smoothly. If both -m and -1	are specified, -1 wins.

       rt(1), fb-png(1), libfb(3), pix(5)

       John R. Anderson

       This software is	Copyright (c) 1998-2019	by the United States
       Government as represented by U.S. Army Research Laboratory.

       Reports of bugs or problems should be submitted via electronic mail to

BRL-CAD				  08/29/2020			     PNG-FB(1)


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