Provided by: xcftools_1.0.7-3ubuntu1_amd64 bug

NAME

       xcf2png - convert from GIMP xcf files to png format

SYNOPSIS

       xcf2png [ options ] filename [ layer names ]

DESCRIPTION

       xcf2png is a command-line tool that converts image files in the XCF format used by gimp(1)
       to the generic image format png, flattening layers if necessary. It does not need to  have
       the Gimp engine itself available.

GENERAL OPTIONS

       -A, --force-alpha
               Invent a trivial alpha channel even if the flattened image is completely opaque.

       -b color, --background color
               Use  this  color  for  transparent pixels in the image.  The color can be given as
               #rrggbb or #rgb hexadecimal values, or as an X11 color name (which will only  work
               if a color name database can be found in one of a number of standard locations).

       -c, --color, --colour
               Force  the  output  to  use  RGB  color  space  even  if it there are more compact
               alternatives.

       -C, --autocrop
               Set the converted part of the image such that it just include  the  boundaries  of
               the  visible (or selected) layers.  This may make it either smaller or larger than
               the canvas, depending on the position and size of the visible layers.  (Note  that
               the contents of the layers is not taken into account when autocropping).

               In  the  absence of options that specify otherwise, the converted image will cover
               the entire XCF canvas.

       -D, --dissolve
               Do a "dissolve" step to eliminate partial transparency after flattening.  If -b is
               also given, this happens before the background color is applied.

       -f, --full-image
               First  flatten  the  entire  image  to a memory buffer before writing output. Then
               analyse the image to decide on the details of the output format (e.g.,  whether  a
               grayscale output is sufficient).  Without this option, the program flattens only a
               singe row of "tiles" (height 64) at a time.

       -g, --gray, --grey
               Force the output to be a grayscale image even if it may  be  monochrome.   If  any
               colored  pixels  are  encountered,  exit  with  status 103.  This will be selected
               automatically if the output file's name ends with .pgm.

       -G, --for-gif
               Assert that the flattened image will have no partial transparency (allowing a more
               compact  representation  of  the  alpha  output).   Exit  with  status  102 if the
               flattened image has any partial transparency.  If -b is  also  given,  this  tests
               whether there there is partial transparency before applying the background color.

       -h, --help
               Print an option summery to standard output and exit with a return code of 0.

       -j, --bzip
               Equivalent to -Z bzcat.  Default if the filename ends with bz2.

       -o filename, --output filename
               Write the converted picture to filename instead of to standard output.

       -O x,y, --offset x,y
               Offset the converted part of the image from the top-left corner of the XCF canvas.
               Usually used with -S.

       -S wxh, --size wxh
               Crop the converted image to width w and height h.

       -T, --truecolor
               Use standard RGB compositing for flattening indexed layers.  Without this  option,
               xcf2png  will  mimic  the  Gimp's current strategy of rounding each alpha value to
               either full transparency or full opacity, and interpret all layer modes as Normal.

       -u, --utf8
               Use the raw UTF-8 representation from the XCF file to compare  and  display  layer
               names.   Ordinarily,  layer  names  will  be converted to the character set of the
               current locale.

       -v, --verbose
               Print progress messages about the conversion to standard error.

       -V, --version
               Print the version numer of xcftools to standard output and exit with a return code
               of 0.

       -z, --gzip
               Equivalent to -Z zcat.  Default if the filename ends with gz.

       -Z command, --unpack command
               Specify a command that the input file is filtered through before being interpreted
               as an XCF file. The command is invoked as command filename and must produce output
               to its standard output.  Note that it is not possible to specify arguments as part
               of command.  An uncompressor is selected automatically if the filename  ends  with
               gz  or  bz2;  to  suppress this, use -Z cat (which is implemented without actually
               starting a cat(1) process).

       Several groups of options are mutually incompatible; in each group the one given last will
       win:

       1)  -A and -b.

       2)  -g and -c .

       3)  -D and -G.

       4)  -j, -z, and -Z.

       5)  -C and -O/-S.

LAYER SPECIFICATIONS

       If  no  layer name is given on the command line, all of the visible layers in the XCF file
       are merged to produce the output image.  It is also possible  to  specify  the  layers  to
       merge explicitly, by giving their names as separate arguments after the input filename. In
       that case, the output will contain only the named layers. The layers will be merged in the
       order  they appear on the command line, with the leftmost being "at the bottom" - that is,
       the layer ordering in the XCF file will be ignored.

       The following options can be given after a layer name to override the global properties of
       the layer:

       --mask  Enable the layer mask.

       --mode mode
               Set the layer mode (e.g., Normal or Multiply).

       --nomask
               Disable the layer mask.

       --opacity n
               Set the opacity on a scale from 0 to 255 (as used internally)

       --percent n
               Set the opacity on a scale from 0 to 100 (as in the Gimp user interface).

EXIT STATUS

       The exit status of xcf2png is

       0    Success

       20   Problems  parsing  the  command line, including unknown color names (or missing color
            name directory) for -b.

       21   The specified XCF file does not exist or cannot be read.

       22   A layer named on the command line was not found, or the --mask option was used for  a
            layer that has no layer mask.

       102  The -G option was given, yet partial transparency was found.

       103  -g was given, yet colored pixels were found.

       123  The  XCF file contains presumably valid features that xcftools does not support.  (As
            of this writing there is no known way of getting the Gimp to write an XCF  file  that
            will provoke this return. Please notify the author if you discover one).

       125  The XCF file is malformed.

       126  An uncompression program could not be executed, or terminated abnormally.

       127  Unexpected I/O error, internal errors, or other "this can't happen" situations.

       If  an  uncompression  program  returns  an  error exit status, this will be returned from
       xcf2png too.

BUGS AND LIMITATIONS

       When several partially transparent layers are merged, the pixel  values  are  interpolated
       without gamma correction. (The Gimp also does it this way). Some slight rounding errors in
       the interpolation are inevitable; xcf2png sometimes has different rounding errors than the
       Gimp  itself, especially when more than two layers are involved, or in case of some of the
       more exotic layer modes.  These differences are usually not visible to the eye.

       Floating selections are currently not handled correctly.

       There are probably other bugs lurking in corner cases. If you discover one, please  notify
       the author.

FILES

       /etc/X11/rgb.txt

       /usr/share/X11/rgb.txt

       /usr/lib/X11/rgb.txt
               Color name database for -b.

AUTHOR

       xcf2png was written by Henning Makholm <henning@makholm.net>.

SEE ALSO

       xcfinfo(1), xcf2pnm(1)