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ActiveTcl User Guide
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[ Main table Of Contents | Img Table Of Contents | Img Index ]
img-jpeg(n) 1.3 "Img"
img-jpeg - Img, Joint Picture Expert Group format (jpeg)
package require Tk
package require img::jpeg ?1.3?
The package img::jpeg 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::jpeg.
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 Joint Picture Expert Group format
(jpeg). More specifically img::jpeg extends
Tk's photo image type.
The name of the new format handler is jpeg.
This handler provides new additional configuration options. See
section JPEG OPTIONS for more detailed
explanations.
All of the above means that in a call like
- image create
photo ?name? ?options?
- Image data in jpeg format (options -data and
-file) is detected automatically.
- The format name jpeg 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 JPEG
OPTIONS.
The handler provides six options, two effective when reading
from a JPEG image, and five influencing the writing of such. One
option is usable for both reading an writing.
- -fast
- This option is for reading from JPEG data. It usage activates a
processing mode which is fast, but also provides only low-quality
information.
- -grayscale
- This option can be used for both reading and writing of JPEG
data. Usage of this option forces incoming images to grayscale, and
written images will be monochrome.
- -quality n
- This option is for writing JPEG data. It specifies the
compression level as a quality percentage. The higher the quality,
the less the compression. The nominal range for n is 0...100. Useful
values are in the range 5...95.
The default value is 75.
- -smooth n
- This option is for writing JPEG data. When used the writer will
smooth the image before performing the compression. Values in the
10...30 are usually enough. The
default is 0, i.e no smoothing.
- -optimize
- This option is for writing JPEG data. It usage causes the
writer to optimize the huffman table used to encode the jpeg
coefficients.
- -progressive
- This option is for writing JPEG data. It usage causes the
creation of a progressive JPEG file.
img-bmp , img-gif , img-ico ,
img-intro , img-jpeg , img-pcx ,
img-pixmap , img-png , img-ppm ,
img-ps , img-sgi , img-sun ,
img-tga , img-tiff , img-window , img-xbm , img-xpm
image handling , jpeg , tk
Copyright © 1995-2003 Jan Nijtmans
<nijtmans@users.sourceforge.com>