Provided by: libtk-img-doc_1.4.2-4ubuntu1_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?


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>

img-png                                                1.4                                          img-png(3tk)