img-jpeg(3tk)
NAME
img-jpeg - Img, Joint Picture Expert Group format (jpeg)
SYNOPSIS
package require Tk package require img::jpeg ?1.4? image create photo ?name? ?options? ______________________________________________________________________________
DESCRIPTION
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?
[1] Image data in jpeg format (options -data and -file) is detected
automatically.
[2] 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.
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.
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, jpeg, tk
COPYRIGHT
Copyright (c) 1995-2009 Jan Nijtmans <nijtmans@users.sourceforge.net>
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