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img-png(n)			      Img			    img-png(n)


       img-png - Img, Portable Network Graphics	format (png)

       package require Tk

       package require img::png	 ?1.4?

       image create photo ?name? ?options?


       The  package  img::png  is  a sub-package of Img. It can	be loaded as a
       part of the complete Img	support, via package require Img,  or  on  its
       own, via	package	require	img::png.

       Like  all packages of Img it does not provide new commands, but extends
       the existing Tk command image so	 that  it  supports  files  containing
       raster  images  in  the	Portable  Network  Graphics format (png). More
       specifically img::png extends Tk's photo	image type.

       The name	of the new format handler is png.  This	handler	 provides  new
       additional  configuration options. See section PNG OPTIONS for more de-
       tailed explanations.

       All of the above	means that in a	call like

       image create photo ?name? ?options?

       [1]    Image data in png	format (options	-data and -file)  is  detected

       [2]    The format name png is recognized	by the option -format.	In ad-
	      dition the value for the option is treated as list and may  con-
	      tain any of the special options listed in	section	PNG OPTIONS.

       The handler provides the	following options:

       -verbose	bool
	      This option is supported for reading only.

	      If  set to true, additional information about the	file format is
	      printed to stdout. Default is false.

       -gamma float
	      This option is supported for reading only.

	      Use the specified	gamma value when reading an image.   This  op-
	      tion overwrites gamma values specified in	the file.  If this op-
	      tion is not specified and	no gamma value is in the file,	a  de-
	      fault value of 1.0 is used.

       -matte bool
	      This option is supported for reading only.

	      If set to	false, a matte (alpha) channel is ignored during read-
	      ing or writing. Default is true.

       -alpha float
	      This option is supported for reading only.

	      An additional alpha filtering for	the overall image,  which  al-
	      lows  the	 background  on	 which	the image is displayed to show
	      through.	This usually also has the effect of  desaturating  the
	      image.   The alphaValue must be between 0.0 and 1.0.  Specifying
	      an alpha value, overrides	the setting of the  matte  flag,  i.e.
	      reading  a file which has	no alpha channel (Greyscale, RGB) will
	      add an alpha channel to the image	independent of the matte  flag

       The handler provides no true write options at all, but accepts pairs of
       keys and	values when writing a PNG file.	Each pair will be written as a
       named  text  chunk where	the key	provides the name of the chunk and the
       value its contents.  For	example

		  png Author <name> Title <title> Description ...

       If you want to write images to disk which contain transparency informa-
       tion (e.g. PNG with alpha channel) you need at least Tk 8.3.

       img-bmp,	img-dted, img-gif, img-ico, img-intro, img-jpeg, img-pcx, img-
       pixmap, img-png,	img-ppm, img-ps, img-raw, img-sgi,  img-sun,  img-tga,
       img-tiff, img-window, img-xbm, img-xpm

       image handling, png, tk

       Copyright (c) 1995-2009 Jan Nijtmans <>

img-png				      1.4			    img-png(n)


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