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RLE-FB(1)			    BRL-CAD			     RLE-FB(1)

       rle-fb -	decode run-length encoded image	onto a frame buffer

       rle-fb [-Ocdh] [-F framebuffer] [-C r/g/b] [-S squarescrsize]
	      [-W scr_width] [-N scr_height] [-X scr_xoff] [-Y scr_yoff]

       rle-fb decodes a	University of Utah standard (Edition-3,	or "Utah
       Raster Toolkit")	Run-Length Encoded (RLE) format	file (saved with fb-
       rle(1) or a similar program) to a frame buffer. If file.rle is not
       specified, standard input is read.

       Each RLE	file contains an image rectangle. The Utah Raster Toolkit
       semantics specify that the rle-fb program is to clip the	RLE image
       rectangle to the	screen of the current framebuffer, only	modifying
       pixels in that area. In the case	where the RLE file contains a
       rectangle of size greater than or equal to that of the current screen,
       then all	pixels on the screen are modified. In the case where the RLE
       file contains a rectangle smaller than the screen, or where a portion
       of that rectangle has been positioned outside the bounds	of the screen,
       then this program will only modify those	screen pixels underneath the
       RLE image rectangle. While this is behavior can be a great boon when
       creating	a montage of smaller images, it	behooves the user to arrange
       for a suitable background.

       If the screen size is explicitly	specified by a command line option,
       the framebuffer is opened with exactly that size, and the RLE image
       rectangle is clipped to that size, even if the framebuffer hardware
       could support a larger size. If the screen size is not specified, then
       this program attempts to	open the framebuffer with a size large enough
       to hold the entire RLE image rectangle. If the open succeeds, but the
       full size request is not	honored, then the RLE image rectangle is
       silently	clipped	to the available screen. The RLE image rectangle can
       be repositioned on the screen with the -X and -Y	command	line options,
       as well as by using repos(1).

	   changes the screen size to 1024x1024.

       -W~A scr_width
	   specifies the desired width of the screen, in pixels.

       -N~A scr_height
	   specifies the desired height	of the screen, in scanlines.

       -S~A squarescrsize
	   sets	the screen width and height to the indicated value.

       -F~A framebuffer
	   This	option specifies which framebuffer the image is	to be
	   displayed on. If not	given, the environment variable	FB_FILE	is
	   used	to select the display device (see brlcad(1)). If FB_FILE has
	   not been set, the default device for	your system will be used.

	   The AcAAcrunch colormapAcAA option. If the RLE file contains	a
	   colormap, rather than loading that colormap into the	framebuffer
	   and allowing	the framebuffer	to apply the colormap to produce the
	   final image,	this option causes the colormap	to be applied to the
	   pixel data before it	is sent	to the framebuffer. In this case, the
	   colormap in the framebuffer is undisturbed. This can	be useful to
	   preserve dramatic images created with weird color maps such that
	   Gamma correction (e.g., for film) can also be applied. This option
	   is recommended when producing images	for export to other display
	   systems, so that variations in the interpretation of	color maps
	   between different types of display hardware do not affect the
	   displayed image.

	   Debug option, provides a verbose description	of the input file
	   structure and image decoding	process, written on standard error.

	   Restores the	image data in overlay mode. Only areas of the original
	   image which were not	the background color are decoded. The rest of
	   the image already in	the frame buffer is undisturbed. That this
	   mode	uses twice as many DMAs	to the frame buffer as the normal
	   mode. This is because each scanline of the previous image must be
	   read	from the framebuffer, the overlay portions of the new image
	   written on top, and the composite scanline must be written back to
	   the framebuffer.

       -C~A r/g/b
	   If the image	is not being decoded in	overlay	mode, the background
	   is normally set to the value	recorded in the	RLE file. This option
	   permits the user to specify an alternate background color as	a
	   red/green/blue triple, separated by slashes (AcAA/AcAA). The	color
	   intensity in	each channel ranges from 0 (dark) to 255 (bright).

       -X~A scr_xoff
	   Specify a screen X offset, which will offset	the file onto the
	   screen by the given amount. (i.e., -X~A 10 would place (0,0) in the
	   RLE image rectangle at screen coordinate (10,0). The	offset may be
	   negative or positive. The RLE image rectangle will be clipped to
	   the screen, as required.

       -Y~A scr_yoff
	   Specify a screen Y offset, which will offset	the file onto the
	   screen by the given amount.

	   Name	of file	to decode, in RLE format. If not specified, standard
	   input is used instead.

       The run length encoded image format is best used	for the	long-term
       storage of images, as it	uses less disk storage than a pix(5) file, at
       the expense of requiring	more processing	for the	encoding and decoding.
       This program is also useful when	using the Utah Raster Toolkit
       utilities, which	only operate on	RLE encoded files; this	program	will
       display their results on	a framebuffer.

       Simple compositing of images can	be done	with the -O overlay flag on
       rle-fb(1). More sophisticated compositing can be	achieved using some of
       the other tools.	For RLE	files, comp(1),	crop(1), repos(1),
       rlepatch(1), and	rlebox(1) can be used. For pix(5) files, pixrect(1),
       pixscale(1), and	pixmerge(1) are	used.

       AcAArle-fb AcAAtruck.rle	AcAArle-fb AcAA-O AcAAtext.rle AcAArle-fb
       AcAA-C 0/255/0 AcAA<car.rle

       AcAArle-fb: excess arguments ignoredAcAA.
	   More	than one RLE file name was specified.

       AcAArle-fb: Error reading setup informationAcAA.
	   The subroutine rle_get_setup() returned an error code. Either the
	   file	is not in Edition-2 or Edition-3 RLE format, or	the file has
	   been	damaged	or truncated. If the file is in	Edition-1 RLE format,
	   the orle-fb(1) program can be used to display the file.

       AcAArle-fb: Warning: RLE	image rectangle	entirely off screenAcAA
	   The combined	effects	of the RLE image rectangle definition stored
	   in the RLE file and any -X and -Y command line options have
	   resulted in the RLE image rectangle being shifted entirely off the
	   screen. While this is not an	error, no screen pixels	were changed.
	   This	may not	have been the intent of	the user, so the message is

       AcAArle-fb: correcting for old style colormapAcAA.
	   The only change between the Edition-2 and Edition-3 RLE file
	   formats that	is not upwards compatible is the format	of the
	   colormap. Edition-2 stored eight bits of data right justified in a
	   16-bit field, while Edition-3 stores	a full 16-bit field. In	order
	   to allow this program to decode images stored in the	Edition-2
	   format, any colormap	which has the upper eight bits all zero	in all
	   colormap entries is assumed to be an	Edition-2 colormap, and	is
	   adjusted for	suitable display. While	this heuristic may be
	   AcAAtrickedAcAA with	an Edition-3 colormap with degenerate values,
	   the picture would have been very dark, and the benefits of full
	   upwards compatibility from Edition-2	format files were deemed worth
	   this	risk.

       brlcad(1), fb-rle(1), rle-pix(1), pix-rle(1), pixrect(1), pixscale(1),
       pixmerge(1), comp(1), crop(1), repos(1),	rlepatch(1), rlebox(1),

       BRL-CAD Team

       This software is	Copyright (c) 1988-2013	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				  07/08/2017			     RLE-FB(1)


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