|
ActiveTcl User Guide
|
|
|
[ Main table Of Contents | Tcllib Table Of Contents | Tcllib Index ]
jpeg(n) 0.1 "Image manipulation"
jpeg - JPEG querying and manipulation of meta data
TABLE OF
CONTENTS
SYNOPSIS
DESCRIPTION
COMMANDS
LIMITATIONS
KEYWORDS
COPYRIGHT
package require Tcl 8.2
package require jpeg ?0.1?
This package provides commands to query and modify JPEG images.
JPEG stands for Joint Photography Experts Group and is a
standard for the lossy compression of photographical images. It is
specified at LINK_HERE.
- ::jpeg::isJPEG file
- Returns a boolean value indicating if file
is a JPEG image.
- ::jpeg::imageInfo file
- Returns a dictionary with keys version,
units, xdensity,
ydensity, xthumb, and
ythumb. The values are the associated properties
of the JPEG image in file. Throws an error if file is not a JPEG image.
- ::jpeg::dimensions file
- Returns the dimensions of the JPEG file as a
list of the horizontal and vertical pixel count. Throws an error if
file is not a JPEG image.
- ::jpeg::getThumbnail file
- This procedure will return the binary thumbnail image data, if
a JPEG thumbnail is included in file, and the
empty string otherwise. Note that it is possible to include
thumbnails in formats other than JPEG although that is not common.
The command finds thumbnails that are encoded in either the JFXX or
EXIF segments of the JPEG information. If both are present the EXIF
thumbnail will take precedence. Throws an error if file is not a JPEG image.
|
set fh [open thumbnail.jpg w+]
puts -nonewline $fh [::jpeg::getThumbnail photo.jpg]
close $fh
|
- ::jpeg::getExif file ?section?
- section must be one of main
or thumbnail. The default is
main. Returns a dictionary containing the EXIF
information for the specified section. For example:
|
set exif {
Make Canon
Model {Canon DIGITAL IXUS}
DateTime {2001:06:09 15:17:32}
}
|
Throws an error if file is not a JPEG
image.
- ::jpeg::formatExif keys
- Takes a list of key-value pairs as returned by getExif and formats many of the values into a more human
readable form. As few as one key-value may be passed in, the entire
exif is not required.
|
foreach {key val} [::jpeg::formatExif [::jpeg::getExif photo.jpg]] {
puts "$key: $val"
}
|
|
array set exif [::jpeg::getExif photo.jpg]
puts "max f-stop: [::jpeg::formatExif [list MaxAperture $exif(MaxAperture)]]
|
- ::jpeg::exifKeys
- Returns a list of the EXIF keys which are currently understood.
There may be keys present in getExif data that
are not understood. Those keys will appear in a 4 digit hexadecimal
format.
- ::jpeg::removeExif file
- Removes the Exif data segment from the specified file and
replaces it with a standard JFIF segment. Throws an error if file is not a JPEG image.
- ::jpeg::stripJPEG file
- Removes all metadata from the JPEG file leaving only the image.
This includes comments, EXIF segments, JFXX segments, and
application specific segments. Throws an error if file is not a JPEG image.
- ::jpeg::getComments file
- Returns a list containing all the JPEG comments found in the file. Throws an error if file is
not a valid JPEG image.
- ::jpeg::addComment file text...
- Adds one or more plain text comments to the
JPEG image in file. Throws an error if file is not a valid JPEG image.
- ::jpeg::removeComments file
- Removes all comments from the file specified. Throws an error
if file is not a valid JPEG image.
- ::jpeg::replaceComment file text
- Replaces the first comment in the file with the new text. This is merely a shortcut for ::jpeg::removeComments and ::jpeg::addComment Throws an error if file is not a valid JPEG image.
- ::jpeg::debug file
- Prints everything we know about the given file in a nice
format.
- ::jpeg::markers channel
- This is an internal helper command, we document it for use by
advanced users of the package. The argument channel is an open file handle positioned at the start of
the first marker (usually 2 bytes). The command returns a list with
one element for each JFIF marker found in the file. Each element
consists of a list of the marker name, its offset in the file, and
its length. The offset points to the beginning of the sections
data, not the marker itself. The length is the length of the data
from the offset listed to the start of the next marker.
can only work with files cant write exif data gps exif data not
parsed makernote data not yet implemented
comment , exif , image , jfif , jpeg , thumbnail
Copyright © 2004, Code: Aaron Faupell
<afaupell@users.sourceforge.net>
Copyright © 2004, Doc: Andreas Kupries
<andreas_kupries@users.sourceforge.net>