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>