Provided by: libtk-img-doc_1.4.2+dfsg-2_all bug

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


SYNOPSIS
       package require Tk

       package require img::png  ?1.4?

       image create photo ?name? ?options?

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DESCRIPTION
       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 detailed 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 automatically.

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


PNG OPTIONS
       The handler provides the following options:

       -matte bool
              This option is supported for reading only.

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

       -alpha float
              This option is supported for reading only.

              An additional alpha filtering for the overall image, which allows  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 setting.

       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 ...


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


SEE ALSO
       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


KEYWORDS
       image handling, png, tk


COPYRIGHT
       Copyright (c) 1995-2009 Jan Nijtmans <nijtmans@users.sourceforge.net>