Provided by: libtk-img-doc_1.4.7+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:

       -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 option overwrites gamma values
              specified in the file.  If this option is not specified and no gamma  value  is  in  the  file,  a
              default 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 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>